Fix indexed png transparecy

Former-commit-id: 22b1bb758cdbd1a858c7e3cdcc1896c67302ad51
Former-commit-id: 9439de1c305648648f7348a9b7852b137c83720a
Former-commit-id: 7a1d86a944909bd5e68ea96070ecf16641d3b1db

src/ImageProcessorCore/Formats/Png/PngEncoderCore.cs

@@ -89,7 +89,11 @@ namespace ImageProcessorCore.Formats
                 0,
                 8);
 
-            this.Quality = image.Quality.Clamp(1, int.MaxValue);
+            if (image.Quality > 0)
+            {
+
+                this.Quality = image.Quality.Clamp(1, int.MaxValue);
+            }
 
             this.bitDepth = this.Quality <= 256
                                ? (byte)(this.GetBitsNeededForColorDepth(this.Quality).Clamp(1, 8))
@@ -234,11 +238,7 @@ namespace ImageProcessorCore.Formats
             // Write the transparency data
             if (this.quantized.TransparentIndex > -1)
             {
-                byte[] buffer = BitConverter.GetBytes(this.quantized.TransparentIndex);
+                this.WriteChunk(stream, PngChunkTypes.PaletteAlpha, new[] { (byte)this.quantized.TransparentIndex });
-
-                Array.Reverse(buffer);
-
-                this.WriteChunk(stream, PngChunkTypes.PaletteAlpha, buffer);
             }
         }