Suggestion: add a Pixel Aspect Ratio test

[sdsnatcher]

Pixel Aspect Ratio metadata is a very useful feature of many image formats (JPG, PNG, GIF, etc) that surprisingly no browser has implemented yet.

There's a standalone test for this feature at this page, but it would be nice to have such test included in the score on the HTML5test.

Without native Pixel Aspect Ratio support, it's a nightmare to support images that have non-square pixels, like DVD/DV frames (both 4:3 and anamorphic), and images from any classic computer/video-game from the 80s/90s.

Both Photoshop and GIMP have Pixel Aspect Ratio support for years now, but the browsers refuse to display the images correctly.

"Artificial" stretching is normally used to compensate for the aspect ratio. This is when the image is manually scaled and saved again. But this leads to many problems:

1. Even if saved as PNG, it's a lossy method, that ruins the image to the point that it's not possible to recover the exact original pixeling anymore
2. Terrible compression ratios. The image file size becomes much larger than the original. To try to compensate for that, many users switch to JPG, that adds even more lossy artefacts to the mess.

References:

• Dot clock rates and Pixel Aspect Ratios
• DOS games Pixel Aspect Ratio