From 5a975d0d755d3b3c80947c01a895f8c4bd244779 Mon Sep 17 00:00:00 2001
From: radialmonster <radial@gmail.com>
Date: Sat, 10 Oct 2026 17:20:31 -0400
Subject: [PATCH] LR-IMP-FORMATS: CR3 CRX quantization 44 (QP 168) decodes,
 continuing the step sequence

Canon EOS R50 C-RAW files reach QP 168 (quant 44, step 102, measured about 100). The quantization step and the adaptive QP map range accept it; anything above stays rejected. Bumps RENDER_CACHE_VERSION since such files change from the embedded preview to a raw decode.
---
 crates/engine/src/media.rs   |  2 +-
 crates/raw/src/vendor/crx.rs | 18 +++++++++++++-----
 docs/cr3.md                  |  2 +-
 3 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/crates/engine/src/media.rs b/crates/engine/src/media.rs
index 6d5b548f1..d863060ec 100644
--- a/crates/engine/src/media.rs
+++ b/crates/engine/src/media.rs
@@ -62,7 +62,7 @@ impl SettingsHashes {
 }
 
 /// Bump when the pipeline's output changes, to invalidate cached thumbnails.
-pub const RENDER_CACHE_VERSION: u64 = 42;
+pub const RENDER_CACHE_VERSION: u64 = 43;
 
 /// Thumbnails render at one of these long edges (so window/cell size changes reuse the cache).
 pub const THUMB_SIZES: [usize; 4] = [128, 256, 384, 512];
diff --git a/crates/raw/src/vendor/crx.rs b/crates/raw/src/vendor/crx.rs
index 2d15627fa..64ca37071 100644
--- a/crates/raw/src/vendor/crx.rs
+++ b/crates/raw/src/vendor/crx.rs
@@ -330,8 +330,10 @@ fn tile_qp(sample: &[u8], tile: &Tile) -> Result<Option<QpMap>> {
 
 fn quant_step(value: u8) -> Result<i32> {
     // Measured independently with an external decoder after modifying only the
-    // quantValue field: all forty values 4..43 follow this integer sequence.
-    if !(4..=43).contains(&value) {
+    // quantValue field: all forty values 4..43 follow this integer sequence. Value 44 (QP 168)
+    // continues it (step 102); it was checked against a measured step of about 100 on an EOS R50
+    // C-RAW file. Nothing above 44 has been seen, so it stays rejected.
+    if !(4..=44).contains(&value) {
         return Err(RawError::Unsupported(format!("Canon CRX quantization value {value}")));
     }
     let scale = [40i32, 45, 51, 57, 64, 72].get(usize::from(value % 6)).copied().ok_or_else(|| corrupt("quantization table index"))?;
@@ -754,7 +756,7 @@ fn qp_map(src: &[u8], width: usize, height: usize) -> Result<QpMap> {
             let right = previous.get(x + 1).copied().unwrap_or(above);
             let symbol = bits.qp_rice(k)?;
             let value = median(left, above, corner).checked_add(signed(symbol)).ok_or_else(|| corrupt("QP prediction overflow"))?;
-            if !(131..=167).contains(&value) {
+            if !(131..=168).contains(&value) {
                 return Err(RawError::Unsupported(format!("Canon CRX adaptive QP value {value}")));
             }
             *current.get_mut(x).ok_or_else(|| corrupt("QP outside row"))? = value;
@@ -968,11 +970,11 @@ mod tests {
 
     #[test]
     fn measured_quantization_and_allocation_limits() {
-        for (quant, expected) in [(4, 1), (9, 1), (10, 2), (16, 4), (22, 8), (26, 12), (32, 25), (36, 40), (41, 72), (42, 80), (43, 90)] {
+        for (quant, expected) in [(4, 1), (9, 1), (10, 2), (16, 4), (22, 8), (26, 12), (32, 25), (36, 40), (41, 72), (42, 80), (43, 90), (44, 102)] {
             assert_eq!(quant_step(quant).unwrap(), expected);
         }
         assert!(matches!(quant_step(3), Err(RawError::Unsupported(_))));
-        assert!(matches!(quant_step(44), Err(RawError::Unsupported(_))));
+        assert!(matches!(quant_step(45), Err(RawError::Unsupported(_))));
         for (width, height) in [(20_000, 20_000), (65_538, 2), (2, 65_538)] {
             let mut config = coding();
             config.width = width;
@@ -1003,6 +1005,12 @@ mod tests {
         assert!(matches!(qp_map(&[0, 0, 1, 4, 0x94], 1, 4), Err(RawError::Unsupported(_))));
     }
 
+    #[test]
+    fn qp_168_is_accepted_and_169_is_not() {
+        assert_eq!(qp_map(&[0, 0, 1, 0x50, 0x94], 1, 4).unwrap().data, [168; 4]);
+        assert!(matches!(qp_map(&[0, 0, 1, 0x52, 0x94], 1, 4), Err(RawError::Unsupported(_))));
+    }
+
     #[test]
     fn odd_height_qp_map_uses_its_last_row_alone() {
         // EOS R7 C-RAW: 4732 sensor rows give a 1183-row QP map, so the last
diff --git a/docs/cr3.md b/docs/cr3.md
index ac13d3fda..9b0cc4c72 100644
--- a/docs/cr3.md
+++ b/docs/cr3.md
@@ -26,7 +26,7 @@ decoded.
 
 CRX version `0x100`, four Bayer planes and `ff01`/`ff02`/`ff03` marker headers
 support lossless RAW and three-level C-RAW with horizontal tiles. Uniform
-quantization values 4–43 are independently verified. Version `0x200` C-RAW
+quantization values 4–43 are independently verified; 44 continues the sequence (step 102, checked against a measured step on an EOS R50 C-RAW file). Version `0x200` C-RAW
 supports the `ff11`/`ff12`/`ff13` marker family, a single 14-bit Bayer tile and
 its adaptive quantization map. C-RAW is quantized, so next to clipped highlights
 its reconstruction can overshoot the sensor range by a few quantization steps