More precise bit depth expanding

awxkee · awxkee · commit 092879c9acb3 · 2024-11-02T20:40:07.000Z
diff --git a/src/codecs/avif/decoder.rs b/src/codecs/avif/decoder.rs
@@ -545,7 +545,7 @@ impl<R: Read> AvifDecoder<R> {
         // Expand current bit depth to target 16
         let target_expand_bits = 16u32 - self.picture.bit_depth() as u32;
         for item in target.iter_mut() {
-            *item <<= target_expand_bits;
+            *item = (*item << target_expand_bits) | (*item >> (16 - target_expand_bits));
         }
 
         Ok(())

Original file line number	Diff line number	Diff line change
`@@ -545,7 +545,7 @@ impl<R: Read> AvifDecoder<R> {`
`545`	`545`	`// Expand current bit depth to target 16`
`546`	`546`	`let target_expand_bits = 16u32 - self.picture.bit_depth() as u32;`
`547`	`547`	`for item in target.iter_mut() {`
`548`		`- *item <<= target_expand_bits;`
	`548`	`+ item = (item << target_expand_bits) \| (*item >> (16 - target_expand_bits));`
`549`	`549`	`}`
`550`	`550`
`551`	`551`	`Ok(())`