JEITA CP-3451
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4.4 Specifications Relating to Image Data
4.4.1 Number of Pixels
There is no limit on number of pixels of the primary image when it is recorded as either uncompressed or JPEG
compressed data. Note that when recording as JPEG compressed data images for which the number of lines
(ImageLength) or number of samples/line (ImageWidth) is not a multiple of 8 or 16, the method of recording is as
stipulated in section 4.8.1. The above specification applies similarly to thumbnails.
4.4.2 Pixel Aspect
Image data is recorded as square pixels with a pixel aspect ratio of 1:1. This specification is applied similarly to
thumbnails.
4.4.3 Pixel Composition and Sampling
The combination of pixel composition and pixel sampling for image data shall be RGB 4:4:4 and either Y:Cb:Cr =
4:2:2 or Y:Cb:Cr = 4:2:0. The pixel composition of image data shall also be 8 bits each. This specification is applied
similarly to thumbnails.
As sampling points on the elements making up pixels, the Y and Cb,Cr sampling points may be either co-sited or
centered. Figure 3 shows typical pixel sampling for image width w and height h. In the case of Y:Cb:Cr = 4:2:2,
spatial co-siting is recommended for the sake of improved image quality on TV systems. For Y:Cb:Cr = 4:2:0,
spatial centering is recommended as per the TIFF default and is most common format of the personal computer
applications.