Fix using dither in BmpEncoder when bit per pixel is <= 4

mistoll · mistoll · commit 313b4d277c1c · 2024-10-01T14:55:31.000+02:00
diff --git a/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs b/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
@@ -575,7 +575,9 @@ private void Write4BitPixelData<TPixel>(Configuration configuration, Stream stre
     {
         using IQuantizer<TPixel> frameQuantizer = this.quantizer.CreatePixelSpecificQuantizer<TPixel>(configuration, new QuantizerOptions()
         {
-            MaxColors = 16
+            MaxColors = 16,
+            Dither = this.quantizer.Options.Dither,
+            DitherScale = this.quantizer.Options.DitherScale
         });
 
         frameQuantizer.BuildPalette(this.pixelSamplingStrategy, image);
@@ -623,7 +625,9 @@ private void Write2BitPixelData<TPixel>(Configuration configuration, Stream stre
     {
         using IQuantizer<TPixel> frameQuantizer = this.quantizer.CreatePixelSpecificQuantizer<TPixel>(configuration, new QuantizerOptions()
         {
-            MaxColors = 4
+            MaxColors = 4,
+            Dither = this.quantizer.Options.Dither,
+            DitherScale = this.quantizer.Options.DitherScale
         });
 
         frameQuantizer.BuildPalette(this.pixelSamplingStrategy, image);
@@ -680,7 +684,9 @@ private void Write1BitPixelData<TPixel>(Configuration configuration, Stream stre
     {
         using IQuantizer<TPixel> frameQuantizer = this.quantizer.CreatePixelSpecificQuantizer<TPixel>(configuration, new QuantizerOptions()
         {
-            MaxColors = 2
+            MaxColors = 2,
+            Dither = this.quantizer.Options.Dither,
+            DitherScale = this.quantizer.Options.DitherScale
         });
 
         frameQuantizer.BuildPalette(this.pixelSamplingStrategy, image);

Original file line number	Diff line number	Diff line change
`@@ -575,7 +575,9 @@ private void Write4BitPixelData<TPixel>(Configuration configuration, Stream stre`
`575`	`575`	`{`
`576`	`576`	`using IQuantizer<TPixel> frameQuantizer = this.quantizer.CreatePixelSpecificQuantizer<TPixel>(configuration, new QuantizerOptions()`
`577`	`577`	`{`
`578`		`- MaxColors = 16`
	`578`	`+ MaxColors = 16,`
	`579`	`+ Dither = this.quantizer.Options.Dither,`
	`580`	`+ DitherScale = this.quantizer.Options.DitherScale`
`579`	`581`	`});`
`580`	`582`
`581`	`583`	`frameQuantizer.BuildPalette(this.pixelSamplingStrategy, image);`
`@@ -623,7 +625,9 @@ private void Write2BitPixelData<TPixel>(Configuration configuration, Stream stre`
`623`	`625`	`{`
`624`	`626`	`using IQuantizer<TPixel> frameQuantizer = this.quantizer.CreatePixelSpecificQuantizer<TPixel>(configuration, new QuantizerOptions()`
`625`	`627`	`{`
`626`		`- MaxColors = 4`
	`628`	`+ MaxColors = 4,`
	`629`	`+ Dither = this.quantizer.Options.Dither,`
	`630`	`+ DitherScale = this.quantizer.Options.DitherScale`
`627`	`631`	`});`
`628`	`632`
`629`	`633`	`frameQuantizer.BuildPalette(this.pixelSamplingStrategy, image);`
`@@ -680,7 +684,9 @@ private void Write1BitPixelData<TPixel>(Configuration configuration, Stream stre`
`680`	`684`	`{`
`681`	`685`	`using IQuantizer<TPixel> frameQuantizer = this.quantizer.CreatePixelSpecificQuantizer<TPixel>(configuration, new QuantizerOptions()`
`682`	`686`	`{`
`683`		`- MaxColors = 2`
	`687`	`+ MaxColors = 2,`
	`688`	`+ Dither = this.quantizer.Options.Dither,`
	`689`	`+ DitherScale = this.quantizer.Options.DitherScale`
`684`	`690`	`});`
`685`	`691`
`686`	`692`	`frameQuantizer.BuildPalette(this.pixelSamplingStrategy, image);`