Square versus nonsquare pixels
Pixel Aspect Ratio (PAR) is the ratio of the width of a pixel to its height. When you’re preparing to import graphics into Motion, be aware of the pixel aspect ratio you’re using and whether your project requires you to work with square or nonsquare pixels. Graphics created on a computer, whether scanned, painted, or rendered, will look distorted on a standard-definition video display unless you account for the different pixel aspect ratio.
Use nonsquare pixels for standard-definition projects in NTSC or PAL.
Use square pixels for full-raster high-definition projects, 4K projects, and multimedia video that will be played back only on computers.
Use square pixels for graphics used in projects with decimated raster frame sizes, such as DVCPRO HD formats recorded with a squeezed 1280 x 1080 frame size, but which are later stretched during playback to 1920 x 1080. Raster decimation is a strategy for lowering the data rate of recorded HD video; however, the final result is almost always mastered at the nearest corresponding full-raster resolution. By creating composited graphics and animation at the full-raster resolution used for output, you’ll simplify your asset creation, and guarantee the highest quality.
To display nonsquare pixel video correctly in Motion, click the View pop-up menu above the Canvas, then choose Correct For Aspect Ratio.
Note: Because full-raster high-definition video and 4K video use only square pixels, their images always appear correctly when displayed on SD video displays.