jpeg: Fix corruption with going from rgb to grayscale for progressive…

… images Signed-off-by: caleb <[email protected]>
etemesi254 · Oct 4, 2023 · 62969db · 62969db
1 parent eed3523
commit 62969db
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Showing 2 changed files with 22 additions and 1 deletion.
diff --git a/zune-jpeg/src/mcu.rs b/zune-jpeg/src/mcu.rs
@@ -108,6 +108,8 @@ impl<T: ZReaderTrait> JpegDecoder<T> {
         if self.is_interleaved
             && self.input_colorspace.num_components() > 1
             && self.options.jpeg_get_out_colorspace().num_components() == 1
+            && (self.sub_sample_ratio == SampleRatios::V
+                || self.sub_sample_ratio == SampleRatios::HV)
         {
             // For a specific set of images, e.g interleaved,
             // when converting from YcbCr to grayscale, we need to
@@ -117,6 +119,7 @@ impl<T: ZReaderTrait> JpegDecoder<T> {
             //
             // set coeff to be 2 to ensure that we increment two rows
             // for every mcu processed also
+            mcu_height *= self.v_max;
             mcu_height /= self.h_max;
             self.coeff = 2;
         }

diff --git a/zune-jpeg/src/mcu_prog.rs b/zune-jpeg/src/mcu_prog.rs
@@ -53,7 +53,7 @@ impl<T: ZReaderTrait> JpegDecoder<T> {
     ) -> Result<(), DecodeErrors> {
         setup_component_params(self)?;
 
-        let mcu_height;
+        let mut mcu_height;
 
         // memory location for decoded pixels for components
         let mut block: [Vec<i16>; MAX_COMPONENTS] = [vec![], vec![], vec![], vec![]];
@@ -77,6 +77,24 @@ impl<T: ZReaderTrait> JpegDecoder<T> {
             mcu_width = (self.info.width as usize + 7) / 8;
             mcu_height = (self.info.height as usize + 7) / 8;
         }
+        if self.is_interleaved
+            && self.input_colorspace.num_components() > 1
+            && self.options.jpeg_get_out_colorspace().num_components() == 1
+            && (self.sub_sample_ratio == SampleRatios::V
+                || self.sub_sample_ratio == SampleRatios::HV)
+        {
+            // For a specific set of images, e.g interleaved,
+            // when converting from YcbCr to grayscale, we need to
+            // take into account mcu height since the MCU decoding needs to take
+            // it into account for padding purposes and the post processor
+            // parses two rows per mcu width.
+            //
+            // set coeff to be 2 to ensure that we increment two rows
+            // for every mcu processed also
+            mcu_height *= self.v_max;
+            mcu_height /= self.h_max;
+            self.coeff = 2;
+        }
 
         mcu_width *= 64;