Editing Pixar Image Computer (section)

=== Dumped & Encoded Pixel Data ===

Picture storage (at 2 bytes at byte 426 from start of file) can have values:

1. 0 - 8 bit channels encoded
2. 1 - 12 bit channels encoded
3. 2 - 8 bit channels dumped
4. 3 - 12 bit channels dumped

Dumped tiles store pixel data direct with order RGBA (4 channels), RGB (3 channels), or R (1 channel, grey image) for whole tile and no have extra byte or mark show end of scan line. Encoded tiles use packets for store image data. Each packet have 2 byte header and encoded pixel data after. Two byte header have flag and count for packet, flag is 4 low bits of byte 2, count is top 4 bits of byte 2 (top bits) combine with 8 bits of byte 1 (low bits) create 12 bit count. Flag have values:

{| class="wikitable"
|-
! Flag
! Count
! RGBA
! RGB
! R
! comment
|-
! 0
! no use
! 
!
! 
! end of disk block
|-
! 1
! use
! RGBA RGBA ...
! RGB RGB ...
! R ...
! full channel dump
|-
! 2
! use
! λRGBA λRGBA ...
! λRGB λRGB ...
! λR λR ...
! full channel run
|-
! 3
! use
! A RGB RGB ...
! no use
! no use
! partial channel dump
|-
! 4
! use
! A λRGB λRGB ...
! no use
! no use
! partial channel run
|}

For flag value 1 and 3, count is ''p'' - 1 number of pixels dumped in packet. For flag value 2 and 4, count is ''n'' - 1 number of run lengths in packet, λ is 1 byte (8 bits) store ''p'' - 1 number times repeat same pixel. Flag value 3 and 4 only use one A value for that packet and store only RGBA (4 channels) data. One packet never store pixel data from different scan lines but each scan line can use different/any flag.