Wednesday, 28 August 2013

The Ultimate Guide to Installing Incompatible Android Apps from Google Play


The Ultimate Guide to Installing Incompatible Android Apps from Google Play

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Android developers can restrict their apps to certain devices, countries, and minimum versions of Android. However, there are ways around these restrictions, allowing you to install apps marked as “not compatible with your device.”
Note that these tricks are all unsupported by Google. These tricks require fooling Google Play, and many require root. Some of these tricks may not work properly, as Google doesn’t want us doing these things.
Image Credit: Dru Kelly on Flickr

Why Are Apps Incompatible?

Android developers can restrict their apps in a variety of ways:
  • Some apps are marked as only being compatible with certain phones or tablets. However, they may run just fine on unsupported devices.
  • Other apps are only allowed to be installed in certain countries. For example, you can’t install the Hulu Plus app outside the USA, and some online-banking apps are only available in the bank’s country.
  • All apps have a minimum version of Android they require. For example, Google’s Chrome browser requires Android 4.0 or higher.
Bear in mind that simply installing an incompatible app won’t necessarily make it work. Some apps may actually be incompatible with your device, while other apps (like Hulu) will only work when used within the US (or with a US VPN or DNS service like Tunlr.)
Note that you won’t see incompatible apps when searching via Google Play on your Android smartphone or tablet. They just won’t appear in the search results. You will see incompatible apps when searching on the Google Play website.

Bypass Device Restrictions

Android devices include a build.prop file that identifies the model of the device. if you have a rooted Android device, you can edit the build.prop file and make your device appear to be another device entirely. This will allow you to install apps that are marked as compatible with the other device.
Note that you’ll need to be rooted to use this trick. We have previously shown you how to easily root Nexus devices with WugFresh’s Nexus Root Toolkit. The process will be different for other devices.
We have already described how to edit your build.prop file manually, but there’s now an easier way. The new Market Helper app allows you to spoof another device without editing your build.prop file. It’s much easier, faster, and safer. (However, bear in mind that it also requires root.)
This app isn’t available in Google Play, so you’ll have to grab it from the developer’s website and sideload it. Once it’s installed, open the app and you’ll be able to spoof a popular device like a Samsung Galaxy S3 or a Nexus 7. You can then install apps compatible with that device. After you’re done, you can restart your device and it will appear to be itself again.
android-market-helper
Bear in mind that apps marked as incompatible may actually be incompatible with your device, so some apps may not work properly after you install them.

Tricks for Installing Country-Restricted Apps

Some apps are only available in certain countries. If you have forgotten to install your bank’s app before travelling or you want to install a video or music-playing app that’s not available in your country, you may be able to fool Google into thinking your device is actually in another country.
We have used these tricks in the past to install US-only apps from outside the US. However, none of these tricks worked for us when we tried them while composing the article. It’s possible that Google is sure our account is outside the US because we have paid with a non-US payment method on Google Play. However, we have included these tips in the hopes that they may still work for some of you.
If you do manage to install a country-restricted app, it will become linked to your account, allowing you to install it on your other devices without requiring any tricks in the future.
install-bbc-iplayer-app-outside-uk

Use a VPN to Install Country-Restricted Apps

You can use a VPN to fool Google into thinking your device is in another country. This may only work on devices without cellular connectivity, such as tablets, as Google may use the cellular network your device is on as its location.
Using a VPN doesn’t require root access.  We have previously shown you how to connect to VPNs on Android. If you need a free US or UK-based VPN, try installing the TunnelBear app. TunnelBear only gives you a certain amount of free data per month, but it should be more than enough to install a few apps.
android-tunnelbear-vpn
Restart your Android device, connect to a VPN located in the appropriate country, and then open the Google Play app. Your device should hopefully now appear to be located in another country, allowing you to download apps available in the VPN’s country.
You will need to use something like Tunlr or a VPN app to access country-restricted media services after installing media apps. However, some apps – such as online-banking apps – will work normally in other countries after they’re installed.

Use MarketEnabler to Install Country-Restricted Apps

If you have smartphone with cellular connectivity, Google will use your carrier’s information to determine its country. If you have root access, you can install the MarketEnabler app. This app allows you to spoof other carrier identifiers, making your device appear to be on a carrier in another country. For example, if you select [us] T-Mobile, your phone will appear to be on T-Mobile in the USA.
android-marketenabler
With either the VPN or MarketEnabler trick, you may need to clear the Google Play Store app’s data to make it detect your device’s new country. To do so, open the Settings screen, tap Apps, swipe over to the All list, scroll down to the Google Play Store app, and tap it. Tap Force stop, Clear data, and then Clear cache.
google-play-store-clear-data-and-cache
Re-open Google Play and it should hopefully find your new location.

Install the App’s APK File

If an app is marked as incompatible because you’re in the wrong country, you may be able to locate the app’s .APK file and sideload it onto your device.
Note that downloading and installing random APKs from the web is a security risk, just as downloading random EXE files from unofficial sources is a security risk on Windows. You shouldn’t download APKs from untrusted sources. However, some apps are offered in APK form officially.
You can also have people you know in another country extract the APK file from their device and send it to you. (AirDroid has an easy-to-use extract APK feature.)

Upgrade Your Android Operating System

If you want an app that requires a newer version of Android, you’ll need to update your device to the latest version of Android to get it. Most Android devices aren’t receiving updates, but you can look at installing community-created ROMs like CyanogenMod to get a newer version of Android.
For example, if you have an phone that’s still running Android 2.3, Gingerbread, and you want to install the Chrome browser (only available for Android 4.0, Ice Cream Sandwich, and newer versions of Android), you may find a community-developed ROM like CyanogenMod that can update your device to a newer version of Android, allowing you to install and use the app.
cyanogenmod-header
Image Credit: Johan Larsson on Flickr

Do you know any other tricks for installing incompatible apps? The VPN and MarketEnabler methods for accessing country-restricted apps didn’t appear to work for us anymore, but did they work for you? If not, did you find a better method? Leave a comment and share what you’ve discovered!

Tuesday, 27 August 2013

How to Turn Your Ubuntu Laptop into a Wireless Access Point


How to Turn Your Ubuntu Laptop into a Wireless Access Point

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If you have a single wired Internet connection – say, in a hotel room – you can create an ad-hoc wireless network with Ubuntu and share the Internet connection among multiple devices. Ubuntu includes an easy, graphical setup tool.
Unfortunately, there are some limitations. Some devices may not support ad-hoc wireless networks and Ubuntu can only create wireless hotspots with weak WEP encryption, not strong WPA encryption.

Setup

To get started, click the gear icon on the panel and select System Settings.
Select the Network control panel in Ubuntu’s System Settings window. You can also set up a wireless hotspot by clicking the network menu and selecting Edit Network Connections, but that setup process is more complicated.
If you want to share an Internet connection wirelessly, you’ll have to connect to it with a wired connection. You can’t share a Wi-Fi network – when you create a Wi-Fi hotspot, you’ll be disconnected from your current wireless network.
To create a hotspot, select the Wireless network option and click the Use as Hotspot button at the bottom of the window.
You’ll be disconnected from your existing network. You can disable the hotspot later by clicking the Stop Hotspot button in this window or by selecting another wireless network from the network menu on Ubuntu’s panel.
After you click Create Hotspot, you’ll see an notification pop up that indicates your laptop’s wireless radio is now being used as an ad-hoc access point. You should be able to connect from other devices using the default network name – “ubuntu” – and the security key displayed in the Network window. However, you can also click the Options button to customize your wireless hotspot.
From the wireless tab, you can set a custom name for your wireless network using the SSID field. You can also modify other wireless settings from here. The Connect Automatically check box should allow you to use the hotspot as your default wireless network – when you start your computer, Ubuntu will create the hotspot instead of connecting to an existing wireless network.
From the Wireless Security tab, you can change your security key and method. Unfortunately, WPA encryption does not appear to be an option here, so you’ll have to stick with the weaker WEP encryption.
The “Shared to other computers” option on the IPv4 Settings tab tells Ubuntu to share your Internet connection with other computers connected to the hotspot.
Even if you don’t have a wireless Internet connection available to share, you can network computers together and communicate between them – for example, to share files.

How To Make an Incredibly Easy Panoramic Photograph With Any Camera


How To Make an Incredibly Easy Panoramic Photograph With Any Camera

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You might know that there are special cameras for shooting panoramic pictures. Today, we’ll put one together in seconds that we shot with a regular digital camera and a tripod. Grab your favorite image editor and camera, and let’s go!
Even if you don’t have Photoshop, you’ll be surprised at how easy it can be to take some good shots, merge them, and get a convincing panorama. With our simple tips, you’ll have a much easier time shooting the right kind of images, and splicing them together to make the perfect panorama. Keep reading!

Setting Up Your Panoramic Shot

The most difficult part of creating a panoramic image with a non-panoramic camera is simply shooting the images—properly. Assuming some general guidelines are followed, it can be very easy to put together a great panorama.
The first part of the process involves getting a tripod that your camera can mount on and find a relatively level place to shoot your image. If you use an inferior second-hand tripod (like your author) pennies can make a great, cheap fix to level a wobbly mount.
Rotate your shot horizontally on a fixed axis and take multiple shots that overlap. Don’t stop at four if you want more! You can create a full 360 if you prefer. But when taking your pictures, remember you want to keep them consistent, so it is important to use the same focusshutter speed, and aperture settings, so automatic shooting will make your life more difficult.
Most lenses on DSLRs have manual and automatic settings, as shown above. Take a test picture with fully auto focus, then switch to fully manual to keep the lens from adjusting as you rotate on your axis.
If you aren’t using a DSLR, you may have to refer to your camera’s manual to see if you can disable the auto focus, or simply shoot around it.
Similarly, you don’t want changes in light to affect your shots. Use your own manual settings, or take a test automatic shot, and copy those shutter speed and aperture settings. If you’re unfamiliar with how to use manual settings, you may want to start by reading Technopheniac’s guide to the elements of exposure.
If your camera doesn’t have a full on manual mode, you can use program mode to control as many of the elements of exposure as possible.

Merging Your Pictures

As long as you bracket your images, you’ll probably end up with a set of good, usable pics to make a panorama from. Pick your best set of four or more (although you can merge as few as two!) and pop them into Photoshop.
Make sure all of your images are open in Photoshop, as shown here, all open in multiple tabs. You can make adjustments at this stage if you want to develop the Raw images—since you can adjust all the images at once, you can ensure they stay as consistent as possible. When they’re all open, you can proceed to the next step.
Navigate to File > Automate > Photomerge. This is a feature for newer versions of Photoshop, but don’t dismay if you’re using an older version or even the GIMP, we’ll address that later.
Photomerge has a dialog box like this one. We’ll add our files to the tool, then select how we’d like Photoshop to make our panorama.
“Add Open Files” is straightforward and saves you the time of digging through your pics again.
While you can use any of the various “layout” settings to get a panorama, we used “reposition” in this case. Try them all to check out the various effects included with the tool. Click “OK” when you’re finished.
This was our first result using only this tool—a perfectly acceptable starting point. We crop our image and we’ve got our panorama completed.
Seriously, after only a single crop, this is what we’re left with. Our panorama is high resolution, and pretty convincing. Let’s take a look at what’s going on to create the image.
 
Photoshop has aligned the images in a single file and created image masks to stitch them together nearly seamlessly. Here are two screenshots of two separate layers. You can clearly see where Photoshop fit the two layers together.
This is what your new file’s layers will look like. This is important, because you can do this manually, and you don’t even need Photoshop. Let’s briefly take a look at that.

What if I Don’t Have Photoshop? (or Photomerge?)

Even though Photomerge makes making a panorama ludicrously easy, it’s not terribly difficult to manually align and mask images in Photoshop or even GIMP.
Start by using the move tool and nudge the images until they more or less fit together as shown. They don’t have to be (nor will they be) perfect. All manner of things could cause problems—your lens could be distorting the image, your tripod could have moved, etc. Just do your best and trust that you can mask out the worst parts later.
Find these areas that appear incongruous in your image, create masks and use soft edged paintbrushes to gently blend them together. Don’t follow hard edges or the edge of your photograph! Simply paint weird organic shapes like the ones shown here in the selection to smoothly and invisibly mask out the parts of your panorama that don’t fit together perfectly. You’ll get a result very much like the automated image.

Results and a Final Image

You can tweak your image and spend all manner of time fixing it, just like any photograph, but you’ll probably be pleasantly surprised when you put your images together just how easy it can be, providing you take the proper precautions when you take your images. I really can’t stress how important that is.

Enjoy making your own panoramic photographs! Join the discussion, and address questions on the process or tell us about your own tricks and methods for making panoramas in the comments section below. And if you make some fun panoramic images, feel free to send them along to ericgoodnight@howtogeek.com, and we may choose your pictures to share with all of How-to Geek’s readers.
Image Credits: All images by the author, protected under Creative Commons, attribution toEric Z Goodnight

Technopheniac Explains: Why You Need An Antivirus on Windows, No Matter How Careful You Are.


Technopheniac Explains: Why You Need An Antivirus on Windows, No Matter How Careful You Are.

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Whenever antivirus software is mentioned, someone always seems to chime up and say they don’t need an antivirus because they’re careful. This isn’t true. No matter how smart think you are, you can still benefit from an antivirus on Windows.
The idea that antivirus software is only necessary for irresponsible Windows users is a myth, and a dangerous one to spread. In an age where zero-day vulnerabilities are found and sold to organized crime with alarming frequency, even the most careful of users are vulnerable.

Being Smart Only Helps So Much

Many people think that you can only get malware by downloading suspicious files, running unpatched software, visiting the wrong websites, and doing other irresponsible things likehaving the Java plug-in enabled in your web browser. It’s true – this is how most people pick up malware. But this isn’t the only way malware can spread.
We have previously written about “zero-day” exploits – vulnerabilities that the bad guys find first. Ones we don’t know about, which we can’t protect ourselves from. At events like Pwn2Own and Pwnium, contestants are challenged to compromise fully patched software like Chrome, Firefox, Internet Explorer, Adobe Flash, and more for a financial reward. These browsers and plug-ins inevitably fall as the contestants use unpatched security flaws to crack their security.
These flaws are corrected as soon as they’re found, but new ones inevitably pop up.
In other words, your computer could be infected just from you visiting a website. Even if you only visit websites you trust, the website itself could be compromised – something that happens with alarming frequency these days.

An Antivirus is the Final Layer of Protection

An antivirus is your final layer of protection. If a website uses a security flaw in your browser or a plug-in like Flash to compromise your computer, it will often attempt to install malware – keyloggers, Trojans, rootkits, and all sorts of other bad things. These days, malware is the domain of organized crime looking to gather financial information and harness your computer for botnets.
If a zero-day in a piece of software you use does give the bad guys an opportunity to get malware onto your system, an antivirus is your last layer of defense.  It shouldn’t be your only layer of protection, but it is an important one. And there’s no good reason not to run an antivirus on Windows.

Why Wouldn’t You Run an Antivirus?

Some people believe that antivirus software is heavy and slows down your computer. This was certainly true in the past. Older Norton and McAfee antivirus software suites were infamous for slowing down your computer more than actual viruses would. They’re full of notifications and inducements to keep paying for a subscription and buy more expensive security suites, just as adware annoys you with requests to buy products.
This isn’t true anymore. Computers have become so fast that antivirus software doesn’t weigh them down like it used to. There are also more efficient security suites that are lighter on resources. The free Microsoft Security Essentials for Windows 7 or included Windows Defender on Windows 8 are lightweight antivirus programs created by Microsoft. They don’t try to sell you anything at all.
An antivirus program like Microsoft Security Essentials or Windows Defender is free, won’t noticeably slow down your computer, won’t harass you to buy anything, and doesn’t include an annoying update process (it updates through Windows Update). If it does slow things down, you can use exclusions to exempt certain trusted files from the antivirus scans.
Antiviruses like Microsoft Security Essentials are a very low-hassle way to increase your security. There’s no reason not to use them – unless you just want to brag online that you’re too smart for an antivirus.

You Should Still Be Careful

An antivirus is only a single layer of security. No antivirus program is perfect, as all theantivirus tests show nothing catches all malware all of the time. if you don’t exercise caution, you may become infected by malware even if you’re using an antivirus (Of course, performing scans with other antivirus programs may help find malware your antivirus suite can’t find.)
Be careful about the files you download and run, keep your software updated, uninstall vulnerable software like Java, and more – but don’t drop your antivirus defenses completely just because you’re being careful. A zero-day in your browser, a plugin like Flash, or Windows itself could open the door to infection, and an antivirus is your last layer of protection.
Malware isn’t what it used to be – much of it is created by organized crime to capture financial information and other sensitive data. Antivirus software helps you stay ahead of the bad guys by a little bit more, and it’s worth using.

Of course, this advice only applies to Windows. Linux computers don’t need antivirus software, and the reported threat of Android malware has been overblown as long as you play it safe. Windows is still the wild west in many ways, and even Macs have recently been brought to their knees — by Java security flaws, of course.

How to Block a Phone Number From Calling Your Android Phone


How to Block a Phone Number From Calling Your Android Phone

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Blocking a phone number from calling you should be fairly simple in 2013, but it still isn’t. Android doesn’t have a completely integrated blocking solution, and carriers don’t generally offer this basic service for free.
Luckily, there are a variety of ways to block calls anyway, whether you’re dealing with telemarketers that won’t stop calling or other annoying people that just won’t leave you alone.

Integrated Phone Number-Blocking Options

Google doesn’t build the capability to block calls into Android. However, some manufacturers add this feature to their custom skins. For example, some Samsung phones include this feature.
To use this feature, open the Phone app on a Samsung phone, tap the Menu button, and navigate to Call settings -> Call rejection -> Auto reject list. You can check the Unknown option to automatically reject all calls from “Unknown” numbers or tap the Create button and add individual phone numbers you want to block to the list.

Silence Calls or Send Calls to Voicemail

Android does provide a way to have specific numbers always go to your voicemail or play a silent ringtone that won’t disturb you if your phone is in your pocket.
If you set up this feature, you may still end up with voicemails from the number. However, if they’re a telemarketer, they likely won’t leave you a voicemail — so this feature may be more than good enough for blocking the most annoying telemarketers. If someone’s constantly leaving you voicemail messages, this won’t stop them.
To use this feature, just add the number you want to block to your contacts. You can do this by opening the Dialer app, swiping over to the history tab, and tapping the number. Tap the Add to contacts option and the number will be added to your phone’s contacts.
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Go through the contact-adding process and name the contact. You could also add a contact manually, not from the dialer — just ensure the contact is associated with the phone number you want to block.
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Once you’re done, go into the People app and tap the contact you added. Tap the menu button and select All calls to voicemail to automatically send the number’s calls to voicemail or tap Set ringtone and select None to associate the caller with a silent ringtone.
android-send-all-calls-to-voicemail

Block Calls With a Third-Party App

If you actually want to block calls and this feature isn’t integrated into your phone, you may want to try using a third-party app like Mr. Number. You can use apps like this one to automatically hang up on calls, effectively blocking them and preventing them from even getting to your voicemail.
Note that third-party call blocking apps always seem to have some mixed reviews. They don’t appear to work well for some people, and this may depend on your specific Android phone. If the above app doesn’t work for you, you may want to try another call-blocking app from Google Play.
android-automatically-hang-up-on-number

Use Google Voice


If you’re a Google Voice user, you have the ability to block calls from your Google Voice settings. Google Voice will play a message saying the number has been disconnected, so this may even fool telemarketers and other annoying callers into removing you from their spam lists.
Just log in to your Google Voice account online, locate the recent caller you want to block, click the More link, and select Block caller.

Can Your Carrier Help?


Carriers have the ability to block calls, but they often don’t make it easy. Like almost every other service they offer, it will probably cost you additional money. Some carriers may help you block calls if you contact them, some may direct you to their paid services, and some may say it isn’t possible. This all varies from carrier to carrier, so you’ll need to check your carrier’s website or call them and ask what services they offer.

In most situations, you’re probably better off blocking calls on your own end rather than dealing with your carrier, especially if you don’t want to pay any additional monthly fees

What Is the Difference Between 1080p and 1080i?


What Is the Difference Between 1080p and 1080i?

HDTV displays and HD media content are labeled with the designation 1080p and 1080i, but what exactly does that designation mean and how does it impact your purchasing and watching decisions?
Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites.

The Question

SuperUser reader Avirk is curious about the designations he sees on HDTVs and their content as well as how it applies to computer screens. He writes:
I have seen many times resolution of 1080p and I know that mean 1080 pixels but sometime I also seen option on the HDTV is 1080i. So I want to know the exact difference between them and is 1080i video quality available for the laptop too?
I some Googled and got there are some time 1080P rather than 1080p is there any difference between them too or they represent the same?
Let’s dig into the SuperUser contributor answers to get the bottom of things.

The Answer:

SuperUser contributor Rsp goes into great detail explaining the differences between 1080p, 1080i, and when one is preferable over the other. He writes:
I see a range of problems in the answers and comments here (even in some highly-voted answers that provide otherwise very good information) that span from minor deficiencies that need explanation to some serious inaccuracies, so I think that some clarification is needed.
The question is specifically: What is the difference between 1080p and 1080i? so I will start by outlining the main similarities and differences, I’ll add some tips on how to choose the best format and then I will proceed to explain the problems that I found here.
Some of the information presented below is adapted from my answer to Interlacing on a computer monitor but is rewritten to strictly stick to the subject of the difference between 1080p and 1080i.

Resolution

Both 1080p and 1080i have 1080 horizontal lines of vertical resolution which with a widescreen aspect ratio of 16:9 results in a resolution of 1920 × 1080 pixels (2.1 megapixels). It is not true that 1080i has a lower vertical resolution than 1080p.

Frames vs. fields

1080p is a frame-based or progressive-scan video where you are dealing with frames. You have frame rate and it is expressed in frames per second.
1080i is a field-based or interlaced or interleaved video where you are dealing with fields. You havefield rate and it is expressed in fields per second.
A field contains half of the lines of the frame, either even lines or odd lines, and if one field is composed of even lines, then the next one will be composed of odd lines and so on.

Frequencies

1080p has a frame rate of 25 frames per second for TV in PAL countries, 30/1.001 frames per second for TV in NTSC countries and 24 frames per second for cinematography.
1080i has a field rate of 50 fields per second for TV in PAL countries and 60/1.001 fields per second in NTSC countries.
(Note that it is not 30 frames and 60 fields per second for NTSC but actually 30/1.001 and 60/1.001which is approximately 29.97 and 59.94 but the difference is important. Read about the NTSC color encoding on Wikipedia to see why.)

How to think about it

1080p at 25 frames per second: Imagine that you are shooting 25 pictures per second and storing them as bitmaps. Every frame is a full picture from the given instant. Every pixel in that frame was captured at the same time.
1080i at 50 fields per second: Imagine that you are shooting 50 pictures per second but storing onlyhalf of the bitmaps every time – sometimes you store the odd lines and sometimes the even lines. (Note that it is not the same as storing pictures with lower vertical resolution.) Every field is a half of a full picture from the given instant. Every pixel in that field was captured at the same time.

50 halves ≠ 25 full pictures

Contrary to some comments here, interlaced video at 50 Hz does not mean that 25 full pictures per second are shown. It means that 50 halves of pictures are shown but those are halves of 50 different pictures that were shot at 50 distinct moments of time in every second. You not only don’t have 50 full pictures per second - you don’t have any full pictures at all.

Problems with 1080i

Interlacing causes a lot of problems. For example you can’t easily:
  • scale the video
  • rotate the video
  • make video slow motion
  • make video fast motion
  • pause the video
  • grab a still picture frame
  • play video in reverse
without doing some tricks and loosing quality. You don’t get any of those problems with progressive video. In addition the video encoding is harder because the codec never has a full frame to work with.

Problems with 1080p

The drawback is that 1080p as currently in use has a frame rate that is only half of the field rate of 1080i so the motion is noticeably less fluid – in fact it’s exactly twice less fluid which is a lot. You can see it on large flat TVs that often deinterlace the video to be able to display it on their LCD screens (that, unlike CRT displays, are progressive in nature) which is the cause that they display picture of very high resolution but with jerky motion and some deinterlacing artifacts.
Another problem is that usually 1080i is required for TV broadcasting which means that 1080p is simply out of the question for some applications.

Best of both worlds

Using progressive 1080p with 50 or 60/1.001 full frames per second in the future has a potential to eventually solve the above problems but it will require a whole new range of studio equipment including cameras, storage and editing systems so it probably won’t happen anytime soon. The widely used SDI standard for connecting HD video equipment doesn’t have enough bandwidth.
Currently the only way to have a fluid motion with progressive scanning is 720p that has a frame rate that is two times faster than 1080p but the resolution of only 1280 × 720 pixels (instead of 1920 × 1080 pixels) which may or may not be a problem for some applications. There is no 720i.

Conclusion

There is no one clear winner here.
Update: Here are some general guidelines to choose the right format:
  1. Is it for high-definition TV? Use 1080i or whatever is required.
  2. Is it for standard-definition TV? Use 720p and then convert to 576i or 480i.*
  3. Is it for Internet and resolution is more important than fluid motion? Use 1080p.
  4. Is it for Internet and fluid motion is more important than resolution? Use 720p.
(It all assumes that 1080p has a frame rate of 25 or 30/1.001 frames/s, 1080i has a field rate of 50 or 60/1.001 fields/s and 720p has a frame rate of 50 or 60/1.001 frames/s as is currently the case. Hopefully a high resolution progressive format like 1080p with a frame rate of 50 or 60/1.001 frames/s or maybe even higher will make this recommendation obsolete in the future.)
*) For number 2 make sure that your 720p has the frame rate of 50 fps if your target format is PAL or SECAM and 60/1.001 if your target format is NTSC (unfortunately it means that there is no format that can be converted to both PAL/SECAM and NTSC). The reason I recommend using 720p for recording is to greatly simplify the edition process when every frame is complete with no interlacing (throwing out every other line at the end is easier than creating the missing lines if you need them) and you have some extra resolution to work with so you can for example zoom the image slightly without making the result look blurry. (If anyone has any bad experience of using 720p to prepare material for SD PAL or NTSC TV broadcasting then please comment so I could update this recommendation.)

Explaining problems

These are the parts that I found in the answers and comments here that I think need some explanation:
Progressive Scanning is more desirable in almost every case.
I think that progressive scanning is indeed better in every respect, but if we are not talking theoretically about the idea of interlacing but specifically about 1080p and 1080i standards as used today, then one has to take into account the fact that 1080i is often required for TV broadcasting and converting 1080p to 1080i would result in jerky motion.
P is better than I in most cases i believe, which is the important bit.
Again, yes, progressive is better than interlaced all other things being equal, but progressive video with frame rate that is two times smaller than the field rate of interlaced video (which is the case with 1080p and 1080i) is something very different, especially if interlaced video with high field rate is required for TV broadcasting and the high field rate cannot be reproduced from progressively recorded material with lower frame rate.
[In 1080i] all the odd lines are displayed, followed by all the even lines. This means that only 1/2 the resolution (540 lines or pixel rows) is displayed on the screen at any give time – in other words, only 540 pixel rows are displayed at any given time.
No. For LCD all 1080 lines are always displayed, for CRT displays usually much less than half of of the lines are displayed at any given time which is equally true for both 1080i and 1080p.
The phrase “only 540 pixel rows are displayed at any given time” is extremely misleading. All 1080 rows-of-pixels usually are displayed at once (and even if they weren’t, they’d still appear to be to the human eye), but only half of them will be updated in any given frame. It’s effectively the refresh-rate, not the resolution, that’s cut in half.
While it is true that the phrase “only 540 pixel rows are displayed at any given time” is extremely misleading, it is not true that the refresh-rate is cut in half, because in 1080i the refresh rate is two times faster than with 1080p so it is actually the other way around.
1080i60 means that you’re getting 60 half frames (alternating lines) per second, so only 30 complete frames per second.
With 1080i60 you actually get less than 60 fields (or “half frames”) per second, but it doesn’t mean that you get 30 (or almost 30) complete frames per second. In fact you don’t get even a single complete frame per second.

More resources

This is what I consider the best resource on the subject of field-based (aka interlaced or interleaved) and frame-based (aka progressive-scan) video:
See also the following articles on Wikipedia:
I hope it somewhat clarifies the subject.

How to Cheaply and Safely Clean Your Camera’s DSLR Sensor

How to Cheaply and Safely Clean Your Camera’s DSLR Sensor

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If you snap photos with your DSLR long enough, it’s bound to happen: dust will find its way onto your camera’s sensor and begin marring your beautiful photos. Read on as we walk you through a safe multi-step process to return your camera sensor to a factory floor shine.

Why Do I Want to Do This?

The inside of a digital camera is a veritable dust magnet. Every time you swap lenses you’re effectively inviting particles of dust to swirl right in and stick, courtesy of the electrostatic charge the interior of the camera carries, to the mirror, body chamber, and the camera’s sensor. While it’s less than ideal to have dust anywhere inside the body of the camera, the only time it becomes a real nuisance is when it clings to the sensor and appears in your photos.
Once the dust is on the sensor it rarely moves; the only way to banish the gray dots and black spots from your future pictures is to clean the sensor. Most people are completely freaked out by the idea of undertaking such a task, believing that the sensor is far too delicate for mere mortals to touch. We assure you that cleaning your camera’s sensor is not only easy and almost entirely risk free (when done patiently and with the proper tools, of course), but that it’s downright economical.
A typical professional in-factory or certified-shop cleaning usually runs around $75 (plus an additional $25 or so in shipping costs if you have to send it out). $75-100 will get you enough supplies that you can routinely clean your entire stable of digital cameras for yearsbefore restocking.
Over the lifetime of the camera you’ll save enough by performing your own cleanings that you’ll effectively have purchased the camera with the savings.

What Do I Need?

The following tutorial is divided into segments starting with the least aggressive/risky cleaning technique (no contact at all with the sensor) and moving towards the more aggressive techniques (dry and wet contact with the sensor). We recommend purchasing all the tools at once so you’re ready to follow along with the entire tutorial as needed (depending on how dirty your sensor is).
Before we continue, we need to highlight one very important detail. You need to adjust your purchases based on the type of camera you have. We’ll be cleaning a Nikon D80 which has a fairly standard APS-C sized sensor like many consumer DSLRs. If you’re cleaning a camera with a full-frame sensor (such as the Nikon D600 or the Canon EOS 6D) you’ll need to buy a larger electrostatic brush and swab kit suitable for a a full-frame sensor.
A very stern caution before we continue: Buy the right tools. The biggest risk you undertake in cleaning your camera is not that you’ll damage it with proper technique and tools (the filter glass they put over the sensor is quite durable), but that you’ll damage it by using improper tools.
You must not use canned air in place of a the Rocket Air Blaster we recommend. You’ll coat your sensor will all the nasty lubricants and propellants that are in the can of compressed air, and the resulting mess will be agony to clean up. The Rocket Air Blaster we recommend is specifically designed for cleaning electronics and has a filter on the air intake so that you’re blasting clean and contaminant free air out of the nozzle.
By the same token, you can’t just pick up any old art brush and start cleaning your sensor. The brush we recommend (and other brushes like it, designed for DSLR sensor cleaning) is specifically designed to be pure, uncoated, and intended to touch the surface of the sensor.
The same thing goes for the sensor swabs and cleaning fluid. You can’t just grab a box of Q-tips and a bottle of denatured alcohol from the hardware store and achieve the same effect. The swabs and the cleaning fluid are manufactured specifically to be as contaminant free as possible, again, to avoid putting additional contaminants and impurities on the sensor.
In other words, it’s fine to choose to buy the $30 sensor brush instead of the $100 sensor brush, but don’t even think about attempting this with the $2 art supply store brush that happens to look close-enough to the sensor brush we recommended.

Taking a Reference Photo

The very first step in the cleaning process is to take a simple reference photo in order to see how the dust on the sensor is impacting your photos.
It’s difficult to pick out all the bits of dust when you’re taking a regular photograph, as the natural distribution of light and dark elements in a typical photo (shadows, clothing, texture of hair, etc.) will hide all but the most painfully obvious imperfections.
The best way to see the sensor dust via photo reference is to take a photograph of a neutral background (such as a white or light gray wall or the blue sky on a perfectly clear day) with the aperture of the lens closed down as tightly as your lens will allow. This means you want to set your camera to aperture priority mode and adjust the aperture number as high as it will go (you’ll remember from our Depth of Field tutorial that the higher the f-number the smaller the physical opening of the aperture). If you can go to f/22 or higher, that would be ideal.
Even more ideal would be to use a pinhole lens, as pinhole lenses routinely have f-numbers that exceed f/100. The reason we want as small an aperture as possible is that the smaller the aperture of the lens the more directly the light hits the sensor (and thus causes each spec of dust to cast a harder shadow on the sensor’s surface). A spec of dust that’s barely noticeable at f/2 looks like a hole burned right into the photo at f/22+.
Don’t worry if you need to use a longer exposure time to get a nice bright image. We don’t care if the background is in focus (and would prefer that it isn’t perfectly sharp, actually). The specs of dust, by default of being physically attached to the sensor, will stay crisp and unblurred.
Once you’ve snapped the photo, feel free to adjust the brightness/contrast in your favorite photo editing application. The more the dark specs of dust stand out in your reference photo the better.
Be sure to zoom in and really look at the reference image. The photo we have at the beginning of this section is the entire frame reduced to a much smaller size (and even then you can see how absolutely filthy this hard working camera’s sensor is). Let’s zoom in on the upper-middle frame:
You can see the really big and irregular pieces of dust (like the huge black one at the top). Those bits of dust are likely so large they’re visible to the naked eye looking into the camera. The little ones, however, that just leave little circular shadows that look vaguely like blood cells, are the tiny ones we’ll need to clean carefully to remove (and inspect a reference photo or two later to ensure we did in fact remove them).

Preparing for the Initial Cleaning

Before we get down to the business of actually opening up the camera, there are a few important preliminary steps we need to go through in order to make the cleaning process safe, effective, and frustration free.
Completely charge the camera battery. The majority of digital cameras will not allow you to perform the steps necessary for manual cleaning (such as locking the reflex mirror in the up position) unless the camera has well charged battery.
Clean off the exterior of your camera. If the body of your camera is dusty/linty/dirty then there’s a significant chance you’ll introduce that dust and dirt while you’re working on cleaning the camera. It might seem painfully elementary, but take a moment to dust off the body of the camera. We find that a Q-tip or two dampened with the tip of the tongue or a drop of rubbing alcohol is a perfect tool for removing dust and lint from all the little curves and crannies around the body of the camera.
Clean your work space. Now that you’ve cleaned off the body of the camera, clean off your work space. Again, it seems like elementary advice, but if you’re working at your desk with a dusty monitor riser and messy keyboard, you’re just begging for that crud to migrate into your camera, onto your cleaning brush, or to otherwise end up where it doesn’t belong.

No-Contact Sensor Cleaning

There are two principle steps to the no-contact phase of the sensor cleaning process: engaging the dust reduction system and using the blower.
If your camera has a dust reduction system, engage it now. Not all cameras have a dust reduction system (the Nikon D80 we’re using for this tutorial, for example, does not), but if your camera does have one, it’s worth using. Look in the system menu for an entry like “Dust Reduction” or “Dust Removal”. Although each manufacturer uses a slightly different technique, the general idea is that the dust reduction system vibrates the protective glass filter over the camera’s sensor at a very high speed, which causes the particles of dust to shake off. It’s not a perfect system, but if your camera supports it, by all means use it.
Lock up the mirror. DSLR cameras, like the SLR cameras that proceeded them, use a mirror system to allow you to frame your photos through the actual lens. When the camera is not actively engaged in the process of taking the photo, you can look through the eyepiece and a system of mirrors shows you what the film/sensor will see through the lens. When you take the photo the mirror flips up and the light shines onto the film/sensor instead of onto the mirror and up to your eye.
In order to clean the sensor, we need to get the mirror out of the way. Go into your camera’s system menu and look for an entry like “Mirror Lockup” or “Sensor Cleaning”. Most cameras will give you additional instructions like to press the shutter button to lock the mirror up and to lower it down when you are done. We’re going to lock our mirror up now.
Examine the sensor with the loupe. Once the mirror is locked up, remove the lens. With the mirror out of the way, you’ll be able to see the sensor. Now is a perfect time to examine it with your sensor loupe:
Keeping in mind that the lens produces an inverted image which the camera then flips for us, look at the bottom of the sensor in the photo above. That very visible white chunk of dust is the huge black spot that appeared in the upper-middle portion of our first reference photo.
Blow the dust off with the air blaster. After examining the sensor, carefully pick the camera up and invert it. Hold the camera firmly in one hand so that the opening of the camera body is pointed towards the floor. Pick up the air blaster in your other hand and vigorously blast air around the chamber of the camera and at the sensor. Really the only way to go wrong in this portion of the tutorial is to either drop your camera or slam the nozzle of the air blaster into the camera sensor. As long as you take care to hold the camera firmly and not smack the nozzle into the sensor you’ll be fine. Blast away and let the dust drift down and out of the camera body.
Let’s examine the sensor with the loupe again:
Even though the 10x loupe can’t show us every mote of dust on the sensor, it’s pretty obvious that the largest bits of dust have been completely removed. That hulking monster of a dust bunny that was hanging out on the edge of the frame, for example, is long gone.
We’re going to pop our lens back on and take another reference photo. You don’t have to take reference photos between every step (you can clean from the first to last technique straight through), but we’re documenting every step to show you the major and minor changes on the sensor between techniques.
Compared to our first shot, that’s a remarkable difference. Yes there are still some fuzzy spots and a few legitimately dark spots, but just blasting the sensor with air took care of the really big junk. Let’s look at a close up of the upper frame in the same spot we did last time:
That’s pretty fantastic. It’s nice to zoom in on the photo and not have it look like moths had eaten holes in it.
Now that we’ve done the no contact cleaning, let’s move on to dry cleaning the surface with the electrostatic brush.

Dry Cleaning Your DSLR Sensor

In the last section of the tutorial, we used filtered air to blast the loose bits of dust off the sensor glass. Now we’re going to use an electrostatic brush to pick up even more off the glass.
Before we proceed, there is really only one big caution for this portion of the tutorial. When using the sensor brush, your goal is to stay completely on the sensor and to not touching the surrounding area in the camera. Some of the parts within the chamber have lubricating oil/grease on them (a very tiny amount, but still present) and it’s easy to smear it onto the glass of the sensor. It’s not the end of the world (and it won’t ruin your camera by any means), but it is a huge pain to clean off using the swabs later on. Work with a patient and steady hand to avoid making a mess. As long as you take care to aim the brush towards the sensor and avoid touching the walls of the chamber, you should have no problems at all.
Just like in the previous section, we need to lock up the mirror and remove the lens to access the sensor.
Preparing the brush. The brush is self-charging; when the bristles rub together they generate the static charge necessary to lift the particles of dust off the sensor. In order to charge it, use the air blaster to vigorously ruffle the bristles. Do not blow on it or touch the bristles! If you blow on it, touch it, or otherwise mess with the bristles you’ll transfer oil and contaminants. The brush, once removed from it’s storage tube, should touch nothing but the camera sensor.
Cleaning the sensor with the brush. Charge the brush with the blaster and carefully lower it down onto the sensor moving from one side of the sensor to the other in a single motion. Remove the brush from the chamber. It’s important to not dab the brush around like you’re stippling paint or to drag it around; each time you use the brush the charge dissipates after the first contact to be sure to make one clean motion and then remove the brush from the chamber.
Blast the bristles again to blow away the debris it picked up and to recharge it. Repeat the process, examining the sensor with the sensor loupe to detect any changes in the visible dust particles.
Feel free to mix in a little air blast to the chamber along with using the air blaster to recharge the brush. Most times, the sensor brush will loosen dust particles that it may not catch with that pass (or the subsequent one).
After you’ve performed several passes on the sensor and you can’t see any visible dust with the sensor loupe (or that visible dust refuses to budge despite multiple attempts with the brush and air blaster), it’s time to take another reference photo. We saw two very small specs with our sensor loupe, but there’s no way to tell if they’ll appear in photos without actually taking a reference photo.
Obviously, this is the full camera frame shrunk down to a small image, but it’s clear the sensor’s condition is radically cleaner than when we started. Let’s zoom in on that same section we’ve been looking at all along and see what we find:
Unlike in in the previous two close-ups where the dust was painfully obvious, now we feel obliged to provide reference arrows. Those two tiny specs, the only visible dust we could find via the sensor loupe after using the electrostatic brush, are all that remains of the enormous pile of crud that was on our D80′s sensor.
This is the point in the cleaning process where you may decide, based on the results of the reference photo, to consider the job done if there is no or next to no visible dust in your photo.
Since we’re perfectionists (and we’d be awful tutorial writers if we just threw our hands up and went “Ehh, good enough!”), we’re going to forge ahead and finish the process with a wet cleaning to smite the last of the dust mites.

Wet Cleaning Your DSLR Sensor

Wet cleaning is exactly what it sounds like: using fluid to clean the surface of your camera’s sensor. There are a few rules to work by here (and they’ll sound a lot like our warning at the beginning of the tutorial): only use swabs and cleaning fluid designed for camera sensors, and less is more. We don’t want to give the camera a bath, we want to give it an effective but barely damp wipe.
Prepare your materials. If you bought a kit with both lens cleaning pads and sensor swabs, make sure you’re using the sensor swabs for this portion of the tutorial. Sensor swabs, as seen in the photo above, are like little tiny plastic spatulas wrapped in a special cleaning cloth.
Moisten the swab. Remove a single sensor swab from its protective bag. Drip a drop or two of cleaning fluid into the swab. You want just enough fluid to dampen the cloth, but not enough for it to drip into the camera. If you applied too much, just wait about twenty seconds–the cleaning fluid is a very pure and highly concentrated alcohol, so it will evaporate quickly.
Swab the sensor.  Using the same kind of patience and steady movement you used with the electrostatic brush, swab from one side of the sensor to the other with firm pressure. You don’t need to wiggle the swab about; the sensor swab is the exact width of the sensor.
Lift the swab out of the chamber, rotate it to the clean side, and repeat the motion in the opposite direction. In other words, if you went left to right with side A, go right to left with side B.
Do not reuse the swab once you have used each side of it once. Dispose of the swab and repeat the process as necessary with additional swabs. (If you’re trying to be economical with your supplies but not necessarily your time, you can take reference photos between swabbing sessions.)
Let’s take a look at the reference photo we snapped after the first swabbing:
We’re not even going to show you the full frame one, but instead we’re going to jump right into the zoomed in one. Why? Because there’s nothing to see! After blowing, brushing, and finally swabbing the sensor, there isn’t a visible point of dust on the entire sensor.
Not only did the sensor look absolutely sparkling through the sensor loupe, but the reference photo proves that it’s as clean as it was the day it was made (if not cleaner).

That’s all there is to it! Although cleaning your DSLR camera’s sensor seems like an enormously intimidating task that would most certainly end in tears and the purchase of a new camera, it’s actually a pretty straight forward and safe bit of routine maintenance. We spent less on all our supplies than we would have spent to ship our camera off to Nikon for a professional cleaning and the materials like the sensor loupe and brush will last us the life of the camera and beyond.