1-bit TIFFs compressed with CCITT Group 3 did not open, place or
relink: the image decoder reads Group 4 only and refuses Compression 2
(modified Huffman) and Compression 3 (ITU-T T.4).
They are now decoded with hayro-ccitt, the CCITT decoder that EPS
import uses. Compression 2 rows start at a byte and have no EOL codes.
Compression 3 rows follow an EOL code and are one-dimensional, or, with
T4Options bit 0, one- or two-dimensional as each row's tag bit says.
Fill bits, FillOrder 2, either PhotometricInterpretation, strips and
tiles are read.
A file whose pixels would take more than the decoding allowance as
RGBA is refused as too large to draw. A strip or tile whose data ends
before its last row is refused as damaged, and so is a tile larger
than the allowance. The strips and tiles together are read from at
most as many bytes as the file holds.
Part of #1466.
Docs: docs/file-format-parity.md, docs/target-app-parity.md.
TIFFs that store each channel as its own plane (PlanarConfiguration 2)
did not open, place or relink when they were CMYK or grayscale with
extra channels: the image decoder refuses planar CMYK, and the readers
for CMYK inks and for extra samples returned nothing for planar files.
The two readers now read every plane through the tiff crate and put
each pixel's samples together. A planar CMYK TIFF keeps its ink
amounts and is stored as a CMYK TIFF with each pixel's inks together,
at the file's resolution. Grayscale TIFFs with an alpha channel or
other extra channels, and CMYK TIFFs with alpha, read as their chunky
versions do.
A TIFF whose header claims more strips or tiles than the tiff decoder
can count is refused as too large to draw. The decoder multiplies
those counts without a check, which panics in builds with overflow
checks.
Part of #1466.
Docs: docs/file-format-parity.md, docs/target-app-parity.md.
dotCooCoo