JEITA  CP-3451 - 5 - 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.