Filter functions should auto convert palette images

lib/src/filter/adjust_color.dart

@@ -57,6 +57,10 @@ Image adjustColor(Image src,
     return src;
   }
 
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
+
   contrast = contrast?.clamp(0, 2);
   saturation = saturation?.clamp(0, 2);
   gamma = gamma?.clamp(0, 1000);

lib/src/filter/billboard.dart

@@ -12,6 +12,10 @@ Image billboard(Image src,
     Channel maskChannel = Channel.luminance}) {
   const rs = 0.2025; // pow(0.45, 2.0);
 
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
+
   for (final frame in src.frames) {
     final w = frame.width;
     final h = frame.height;

lib/src/filter/bleach_bypass.dart

@@ -7,6 +7,9 @@ Image bleachBypass(Image src,
   const luminanceR = 0.2125;
   const luminanceG = 0.7154;
   const luminanceB = 0.0721;
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   for (final frame in src.frames) {
     for (final p in frame) {
       final r = p.rNormalized;

lib/src/filter/bulge_distortion.dart

@@ -13,6 +13,9 @@ Image bulgeDistortion(Image src,
     Interpolation interpolation = Interpolation.nearest,
     Image? mask,
     Channel maskChannel = Channel.luminance}) {
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   for (final frame in src.frames) {
     final orig = frame.clone(noAnimation: true);
     final w = frame.width;

lib/src/filter/bump_to_normal.dart

@@ -8,7 +8,12 @@ import '../image/image.dart';
 /// height and 1 a high value. The optional [strength] parameter allows to set
 /// the strength of the normal image.
 Image bumpToNormal(Image src, {num strength = 2.0}) {
-  final dest = Image.from(src);
+  Image dest;
+  if (src.hasPalette) {
+    dest = src.convert(numChannels: src.numChannels);
+  } else {
+    dest = Image.from(src);
+  }
 
   final mx = src.maxChannelValue;
   for (final frame in src.frames) {

lib/src/filter/chromatic_aberration.dart

@@ -5,6 +5,9 @@ import '../util/math_util.dart';
 /// Apply chromatic aberration filter to the image.
 Image chromaticAberration(Image src,
     {int shift = 5, Image? mask, Channel maskChannel = Channel.luminance}) {
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   for (final frame in src.frames) {
     final orig = frame.clone(noAnimation: true);
     final w = frame.width - 1;

lib/src/filter/color_halftone.dart

@@ -14,7 +14,9 @@ Image colorHalftone(Image src,
     Image? mask,
     Channel maskChannel = Channel.luminance}) {
   angle = angle * 0.0174533;
-
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   num pattern(int x, int y, int cx, int cy, num angle) {
     final scale = 3.14159 / size;
     final s = sin(angle);

lib/src/filter/color_offset.dart

@@ -11,6 +11,9 @@ Image colorOffset(Image src,
     num alpha = 0,
     Image? mask,
     Channel maskChannel = Channel.luminance}) {
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   for (final frame in src.frames) {
     for (final p in frame) {
       final msk = mask?.getPixel(p.x, p.y).getChannelNormalized(maskChannel);

lib/src/filter/contrast.dart

@@ -19,7 +19,9 @@ Image contrast(Image src,
   if (contrast == 100.0) {
     return src;
   }
-
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   if (contrast != _lastContrast) {
     _lastContrast = contrast;
 

lib/src/filter/convolution.dart

@@ -16,6 +16,9 @@ Image convolution(Image src,
     num amount = 1,
     Image? mask,
     Channel maskChannel = Channel.luminance}) {
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   final tmp = Image.from(src);
   for (final frame in src.frames) {
     final tmpFrame = tmp.frames[frame.frameIndex];

lib/src/filter/copy_image_channels.dart

@@ -13,6 +13,9 @@ Image copyImageChannels(Image src,
     Channel? alpha,
     Image? mask,
     Channel maskChannel = Channel.luminance}) {
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   final dx = from.width / src.width;
   final dy = from.height / src.height;
   final fromPixel = from.getPixel(0, 0);

lib/src/filter/dot_screen.dart

@@ -13,6 +13,9 @@ Image dotScreen(Image src,
     num amount = 1,
     Image? mask,
     Channel maskChannel = Channel.luminance}) {
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   angle = angle * 0.0174533;
   final s = sin(angle);
   final c = cos(angle);

lib/src/filter/edge_glow.dart

@@ -10,7 +10,9 @@ Image edgeGlow(Image src,
   if (amount == 0.0) {
     return src;
   }
-
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   for (final frame in src.frames) {
     final orig = Image.from(frame, noAnimation: true);
     final width = frame.width;

lib/src/filter/gamma.dart

@@ -9,6 +9,9 @@ Image gamma(Image src,
     {required num gamma,
     Image? mask,
     Channel maskChannel = Channel.luminance}) {
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   for (final frame in src.frames) {
     for (final p in frame) {
       final msk = mask?.getPixel(p.x, p.y).getChannelNormalized(maskChannel);

lib/src/filter/grayscale.dart

@@ -6,6 +6,9 @@ import '../util/math_util.dart';
 /// Convert the image to grayscale.
 Image grayscale(Image src,
     {num amount = 1, Image? mask, Channel maskChannel = Channel.luminance}) {
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   for (final frame in src.frames) {
     if (frame.hasPalette) {
       final p = frame.palette!;

lib/src/filter/hexagon_pixelate.dart

@@ -10,6 +10,9 @@ Image hexagonPixelate(Image src,
     num amount = 1,
     Image? mask,
     Channel maskChannel = Channel.luminance}) {
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   for (final frame in src.frames) {
     final w = frame.width - 1;
     final h = frame.height - 1;

lib/src/filter/invert.dart

@@ -5,6 +5,9 @@ import '../util/math_util.dart';
 /// Invert the colors of the [src] image.
 Image invert(Image src,
     {Image? mask, Channel maskChannel = Channel.luminance}) {
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   final max = src.maxChannelValue;
   for (final frame in src.frames) {
     if (src.hasPalette) {

lib/src/filter/luminance_threshold.dart

@@ -11,6 +11,9 @@ Image luminanceThreshold(Image src,
     num amount = 1,
     Image? mask,
     Channel maskChannel = Channel.luminance}) {
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   for (final frame in src.frames) {
     for (final p in frame) {
       final y =

lib/src/filter/monochrome.dart

@@ -12,7 +12,9 @@ Image monochrome(Image src,
   if (amount == 0) {
     return src;
   }
-
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   final nr = color?.rNormalized ?? 0.45;
   final ng = color?.gNormalized ?? 0.6;
   final nb = color?.bNormalized ?? 0.3;

lib/src/filter/noise.dart

@@ -26,7 +26,9 @@ Image noise(Image image, num sigma,
   if (nSigma == 0.0 && type != NoiseType.poisson) {
     return image;
   }
-
+  if (image.hasPalette) {
+    image = image.convert(numChannels: image.numChannels);
+  }
   if (nSigma < 0.0 || type == NoiseType.saltAndPepper) {
     final mM = minMax(image);
     m = mM[0];

lib/src/filter/normalize.dart

@@ -20,7 +20,9 @@ Image normalize(Image src,
   if (mn == mx) {
     return src;
   }
-
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   final fm = mn.toDouble();
   final fM = mx.toDouble();
 

lib/src/filter/pixelate.dart

@@ -26,7 +26,9 @@ Image pixelate(Image src,
   if (size <= 1) {
     return src;
   }
-
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   for (final frame in src.frames) {
     final w = frame.width;
     final h = frame.height;

lib/src/filter/remap_colors.dart

@@ -15,6 +15,9 @@ Image remapColors(Image src,
     Channel green = Channel.green,
     Channel blue = Channel.blue,
     Channel alpha = Channel.alpha}) {
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   final List<num> l = [0, 0, 0, 0, 0];
   for (final frame in src.frames) {
     for (final p in frame) {

lib/src/filter/scale_rgba.dart

@@ -11,6 +11,9 @@ Image scaleRgba(Image src,
   final dg = scale.gNormalized;
   final db = scale.bNormalized;
   final da = scale.aNormalized;
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   for (final frame in src.frames) {
     for (final p in frame) {
       final msk = mask?.getPixel(p.x, p.y).getChannelNormalized(maskChannel);

lib/src/filter/separable_convolution.dart

@@ -10,6 +10,9 @@ Image separableConvolution(Image src,
     {required SeparableKernel kernel,
     Image? mask,
     Channel maskChannel = Channel.luminance}) {
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   final tmp = Image.from(src);
   // Apply the filter horizontally
   kernel

lib/src/filter/sepia.dart

@@ -10,7 +10,9 @@ Image sepia(Image src,
   if (amount == 0) {
     return src;
   }
-
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   for (final frame in src.frames) {
     for (final p in frame) {
       final r = p.rNormalized;

lib/src/filter/sketch.dart

@@ -12,7 +12,9 @@ Image sketch(Image src,
   if (amount == 0) {
     return src;
   }
-
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   for (final frame in src.frames) {
     final width = frame.width;
     final height = frame.height;

lib/src/filter/sobel.dart

@@ -9,7 +9,9 @@ Image sobel(Image src,
   if (amount == 0.0) {
     return src;
   }
-
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   for (final frame in src.frames) {
     final orig = Image.from(frame, noAnimation: true);
     final width = frame.width;

lib/src/filter/solarize.dart

@@ -11,6 +11,9 @@ Image solarize(Image src,
     {required int threshold, SolarizeMode mode = SolarizeMode.highlights}) {
   final max = src.maxChannelValue;
   final thresholdRange = (max * (threshold / 255)).toInt();
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   for (final frame in src.frames) {
     if (src.hasPalette) {
       final p = frame.palette!;

lib/src/filter/stretch_distortion.dart

@@ -9,6 +9,9 @@ Image stretchDistortion(Image src,
     Interpolation interpolation = Interpolation.nearest,
     Image? mask,
     Channel maskChannel = Channel.luminance}) {
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   for (final frame in src.frames) {
     final orig = frame.clone(noAnimation: true);
     final w = frame.width - 1;

lib/src/filter/vignette.dart

@@ -29,6 +29,9 @@ Image vignette(Image src,
     Color? color,
     Image? mask,
     Channel maskChannel = Channel.luminance}) {
+  if (src.hasPalette) {
+    src = src.convert(numChannels: src.numChannels);
+  }
   final h = src.height - 1;
   final w = src.width - 1;
   final cr = color?.rNormalized ?? 0;

test/formats/ico_test.dart

@@ -9,6 +9,16 @@ import '../_test_util.dart';
 void main() {
   group('Format', () {
     group('ico', () {
+      test('encode palette', () async {
+        var img = await decodePngFile('test/_data/png/buck_8.png');
+        img = copyResize(img!, width: 256);
+        img = vignette(img);
+        final ico = IcoEncoder().encode(img);
+        File('$testOutputPath/ico/buck_8.ico')
+          ..createSync(recursive: true)
+          ..writeAsBytesSync(ico);
+      });
+
       test('encode', () {
         final image = Image(width: 64, height: 64)
           ..clear(ColorRgb8(100, 200, 255));