JEITA CP-3451
- 127 -
Recording of restart markers is optional, and conversion to Flashpix is possible without them; but conversion
without restart markers may result in some image quality loss and require a longer processing time.
In order for restart markers to be inserted at 64-pixel Interoperability, the image data width shall be an exact
multiple of 64. Therefore the valid image width is recorded as tag information (PixelXDimension), and the JPEG
compressed data is recorded with the valid image padded to the right to make it an exact multiple of 64 (see
section 4.8.1).
As in the Flashpix standard, padding is used where necessary to achieve exact multiples of 64; and when
converting to Flashpix, the padding data on the right can be treated in the same way as valid image data.
If the image height is not an exact multiple of 64, Exif files are not padded; so when converting to Flashpix it is
necessary to pad the bottom edge of the image.
Figure 55 Image Size Restrictions
SOF Y
=
PixelYDimension
(APP1)
Padding Data
SOF X
PixelXDimension (APP1)
JPEG Data
64x64 Block
(FPX tile)