TIFF read/write (hand-rolled, zero-dependency)

[swperb]

Purpose: common in scanning/print/scientific imaging; advances the "more formats" vision without breaking the single-binary wedge — TIFF is genuinely hand-rollable.
Ease: 🟡 Mod — tagged IFD container; baseline = uncompressed + PackBits (LZW optional).

Tasks

• baseline TIFF reader (uncompressed + PackBits; LZW optional later)
• writer (uncompressed / PackBits)
• .tif/.tiff in img_load/img_save
• tests + README format table

Note: no libtiff — stays zero-dep.

[swperb]

Implementation notes (zero-dep, hand-rolled — no libtiff)

• Spec: TIFF 6.0. Layout: 8-byte header (II/MM byte order + magic 42 + offset to first IFD) → IFD (entry count + entries {tag,type,count,value/offset}) → pixel strips.
• Target baseline: uncompressed (Compression=1) and PackBits (32773); LZW (5) optional later. Handle both byte orders.
• Tags to read/write: ImageWidth(256), ImageLength(257), BitsPerSample(258), Compression(259), PhotometricInterpretation(262), StripOffsets(273), SamplesPerPixel(277), RowsPerStrip(278), StripByteCounts(279).
• Put it in a new src/tiff.c (or inline) and wire .tif/.tiff into the img_load/img_save extension dispatch in src/image.c. Use the from-scratch write_ppm() as the pattern for a hand-rolled codec.
• Security: run dimensions through img_dims_ok() (same decompression-bomb cap as img_load) and use overflow-checked strip/size math.