B2EVO

Pixel aspect ratio in Photoshop

The problem is that whenever I try to open some images (.jpg) within Photoshop, I get a warning message telling me that:
Pixel aspect ratio correction is for preview purposes only. Turn it off for maximum image quality.

For those who don’t know or have a vague idea about pixel ratio, here’s what this is all about.
Pixel aspect ratio specifies the ratio of width to height of one pixel in an image. Frame aspect ratio describes the ratio of width to height in the frame dimensions of an image. For example, D1 NTSC has a pixel aspect ratio of 0.9 (or 0.9 width by 1.0 height). It also has a frame aspect ratio of 4:3 (or 4.0 width by 3.0 height).
Some video formats output the same frame aspect ratio, but use a different pixel aspect ratio. For example, some NTSC digitizers produce a 4:3 frame aspect ratio, with square pixels (1.0 pixel aspect ratio), and a resolution of 640 x 480. D1 NTSC produces the same 4:3 frame aspect ratio, but uses rectangular pixels (0.9 pixel aspect ratio) and a resolution of 720 x 486. D1 pixels, which are always rectangular, are vertically oriented in systems producing NTSC video and horizontally oriented in systems producing PAL video.
If you display rectangular pixels on a square-pixel monitor without alteration, images and appear distorted; for example, circles distort into ovals. However, when displayed on a broadcast monitor, the images are correct.

Solution 1
This is the recommended one! ONLY IF this somehow doesn’t work you should try the other solutions.
In Photoshop (I used CS4) go to and uncheck View -> Pixel Aspect Ratio. This will disable Pixel Aspect Ratio in Ps.
In my case this solution solved the problem.

Pixel Aspect Ratio turned on.

Pixel Aspect Ratio turned off.

Solution 2
Warning this is a FAIL-SAFE action, therefore some precautions should be taken in order to remain in the safety boundaries.
So, before you do this make sure you back up Photoshop’s preferences (in this case: Adobe Photoshop CS4 Prefs.psp).
You must have turned on the “Show hidden files and folders” option in Windows Explorer. [In Windows XP’s Explorer go to Tools -> Folder Options -> View Tab]
The file can be found in
C:Documents and Settingsyour user_nameApplication DataAdobeAdobe Photoshop CS4Adobe Photoshop CS Settings.
This path is valid for CS4. If you have a previous version you should have in mind that you’re looking for Adobe’s Photoshop (your version) folder in which its settings file (the .psp file) is located. The naming for this settings file can vary amongst versions. It can be Adobe Photoshop CS4 Prefs.psp or simply Prefs.psp. It shouldn’t be hard to find once you know what you’re looking for.

Now the actual solution:
Navigate to your Photoshop Settings file (the previously mentioned path) and delete it (in this case Adobe Photoshop CS4 Prefs.psp). This will cause Adobe CS to re-create the preferences; therefore you can then choose NOT to correct the pixel aspect ratio for your images.

Solution 3
If you reached this one you must be doing something wrong or simply you’re out of luck.
Contact Adobe Support or search their knowledge base for a solution.

That’s it. Hope this might be helpful.