Palette color format.

juliusfriedman · Oct 27, 2024 · b315478 · b315478
1 parent 8602a3d
commit b315478
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Showing 2 changed files with 19 additions and 3 deletions.
diff --git a/Codecs/Image/ImageFormat.cs b/Codecs/Image/ImageFormat.cs
@@ -18,7 +18,7 @@ public class ImageFormat : Codec.MediaFormat
 
         public const byte PreMultipliedAlphaChannelId = (byte)'p';
 
-        //Possibly a type which has multiplied and straight types... 
+        //Possibly a type which has multiplied and normal types... 
         //public const byte MixedAlphaChannelId = (byte)'@';
 
         public const byte DeltaChannelId = (byte)'d';
@@ -39,6 +39,10 @@ public class ImageFormat : Codec.MediaFormat
 
         public const byte BlueChannelId = (byte)'b';
 
+        //
+
+        public const byte PaletteChannelId = (byte)'p';
+
         //Printing...
 
         public const byte CyanChannelId = (byte)'c';
@@ -107,6 +111,14 @@ public static ImageFormat Monochrome(int bitsPerComponent)
             });
         }
 
+        public static ImageFormat Palette(int bitsPerComponent)
+        {
+            return new ImageFormat(Common.Binary.ByteOrder.Little, Codec.DataLayout.Packed, new Codec.MediaComponent[]
+            {
+                new(PaletteChannelId, bitsPerComponent)
+            });
+        }
+
         public static ImageFormat RGB(int bitsPerComponent, Common.Binary.ByteOrder byteOrder = Common.Binary.ByteOrder.Little, Codec.DataLayout dataLayout = Codec.DataLayout.Packed)
         {
             return new ImageFormat(byteOrder, dataLayout, new Codec.MediaComponent[]

diff --git a/Codecs/Image/Png/Codec.Png/PngImage.cs b/Codecs/Image/Png/Codec.Png/PngImage.cs
@@ -25,8 +25,9 @@ private static ImageFormat CreateImageFormat(byte bitDepth, byte colorType)
         switch (colorType)
         {
             case 0: // Grayscale
-            case 3: // Indexed-color            
                 return ImageFormat.Monochrome(bitDepth);
+            case 3: // Indexed-color            
+                return ImageFormat.Palette(bitDepth);
             case 4: // Grayscale with alpha
                 return ImageFormat.WithPreceedingAlphaComponent(ImageFormat.Monochrome(bitDepth / 2), bitDepth / 2);
             case 2: // Truecolor (RGB)
@@ -43,7 +44,10 @@ private static ColorType ResolveColorType(ImageFormat imageFormat)
         switch (imageFormat.Components.Length)
         {
             case 1:
-                return ColorType.Grayscale;
+                return 
+                    imageFormat.Components[0].Id == ImageFormat.PaletteChannelId 
+                    ? ColorType.Palette 
+                    : ColorType.Grayscale;
             case 2:
                 return ColorType.GrayscaleWithAlpha;
             case 3: