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Author: Shnatsel

src/lossless_transform.rs

@@ -387,8 +387,11 @@ pub(crate) fn apply_color_indexing_transform(
     table_data: &[u8],
 ) {
     if table_size > 16 {
+        // convert the table of colors into a Vec of color values that can be directly indexed, and that the compiler knows are always 4 bytes in size
         let mut table: Vec<[u8; 4]> = table_data.chunks_exact(4).map(|c| TryInto::<[u8; 4]>::try_into(c).unwrap()).collect();
+        // pad the table to 256 values if it's smaller than that so we could index into it by u8 without bounds checks
         table.resize(256, [0; 4]);
+        // convince the compiler that the length of the table is 256 to avoid bounds checks in the loop below
         let table: &[[u8; 4]; 256] = table.as_slice().try_into().unwrap();
 
         for pixel in image_data.chunks_exact_mut(4) {