From 4ff374990e5561e37b989e09ed55a59fdbf93ecd Mon Sep 17 00:00:00 2001
From: Lilith River <lilith@imazen.io>
Date: Mon, 9 Mar 2026 21:05:09 -0600
Subject: [PATCH] feat: accept sub-byte bit depths for all color types

Previously, sub-byte bit depths (1-7 bits per sample) were only
accepted for Gray and Multiband color types. This extends the
validation to accept all color types (RGB, RGBA, CMYK, CMYKA, YCbCr)
at sub-byte depths.

The data format is unchanged: sub-byte samples remain packed MSB-first
in the output buffer, exactly as for grayscale. Predictors are still
rejected for sub-byte data.

Tested via libtiffpic flower-rgb-contig-02/04 and flower-rgb-planar-02/04.
---
 src/decoder/image.rs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/decoder/image.rs b/src/decoder/image.rs
index 479f07e..70293ac 100644
--- a/src/decoder/image.rs
+++ b/src/decoder/image.rs
@@ -1030,7 +1030,12 @@ impl Image {
                 bit_depth: n,
                 num_samples: _,
             } if n == 8 || n == 16 || n == 32 || n == 64 => {}
-            ColorType::Gray(n)
+            ColorType::RGB(n)
+            | ColorType::RGBA(n)
+            | ColorType::CMYK(n)
+            | ColorType::CMYKA(n)
+            | ColorType::YCbCr(n)
+            | ColorType::Gray(n)
             | ColorType::Palette(n)
             | ColorType::Multiband {
                 bit_depth: n,