experiments/floyd-steinberg-dithering
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Merge branch 'dithering-algorithm'

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Unknown 2018-02-14 19:00:50 +01:00
commit 092368c694
3 changed files with 64 additions and 13 deletions
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63
lib/Dither.dart
View file

@ -21,16 +21,23 @@ class Pixed {
PixelArray pxArr = new PixelArray.fromPixelArray(image); PixelArray pxArr = new PixelArray.fromPixelArray(image);
for (var y = 0; y < pxArr.getHeight(); y++) { for (var y = 0; y < pxArr.getHeight(); y++) {
for (var x = 0; x < pxArr.getWidth(); x++) { for (var x = 0; x < pxArr.getWidth(); x++) {
var px = pxArr.getPixel(x, y); pxArr.setPixel( _quantizePixel(pxArr.getPixel(x, y)) );
px.r = (steps * px.r / 255).round() * (255 ~/ steps);
px.g = (steps * px.g / 255).round() * (255 ~/ steps);
px.b = (steps * px.b / 255).round() * (255 ~/ steps);
} }
} }
return pxArr; return pxArr;
} }
static PixelArray calcQuantizeError(PixelArray original, PixelArray quantized) { static Pixel _quantizePixel(Pixel pixel, [int steps=1]) {
return new Pixel(
pixel.x,
pixel.y,
(steps * pixel.r / 255).round() * (255 ~/ steps),
(steps * pixel.g / 255).round() * (255 ~/ steps),
(steps * pixel.b / 255).round() * (255 ~/ steps),
pixel.a);
}
static PixelArray quantizeError(PixelArray original, PixelArray quantized) {
PixelArray pxArr = new PixelArray.fromPixelArray(original); PixelArray pxArr = new PixelArray.fromPixelArray(original);
for (var y = 0; y < pxArr.getHeight(); y++) { for (var y = 0; y < pxArr.getHeight(); y++) {
for (var x = 0; x < pxArr.getWidth(); x++) { for (var x = 0; x < pxArr.getWidth(); x++) {
@ -43,6 +50,47 @@ class Pixed {
} }
return pxArr; return pxArr;
} }
static Pixel _quantizeErrorPixel(Pixel original, Pixel quantized) {
return new Pixel(original.x, original.y,
original.r - quantized.r,
original.g - quantized.g,
original.b - quantized.b,
original.a);
}
static PixelArray dither(PixelArray image) {
PixelArray pxArr = new PixelArray.fromPixelArray(image);
for (var y = 0; y < pxArr.getHeight()-1; y++) {
for (var x = 1; x < pxArr.getWidth()-1; x++) {
Pixel origPx = pxArr.getPixel(x, y);
Pixel quantPx = _quantizePixel(origPx);
Pixel errPx = _quantizeErrorPixel(origPx, quantPx);
pxArr.setPixel(quantPx);
Pixel px = pxArr.getPixel(x+1, y);
px.r = (px.r + errPx.r * (7/16)).toInt();
px.g = (px.g + errPx.g * (7/16)).toInt();
px.b = (px.b + errPx.b * (7/16)).toInt();
px = pxArr.getPixel(x-1, y+1);
px.r = (px.r + errPx.r * (3/16)).toInt();
px.g = (px.g + errPx.g * (3/16)).toInt();
px.b = (px.b + errPx.b * (3/16)).toInt();
px = pxArr.getPixel(x, y+1);
px.r = (px.r + errPx.r * (5/16)).toInt();
px.g = (px.g + errPx.g * (5/16)).toInt();
px.b = (px.b + errPx.b * (5/16)).toInt();
px = pxArr.getPixel(x+1, y+1);
px.r = (px.r + errPx.r * (1/16)).toInt();
px.g = (px.g + errPx.g * (1/16)).toInt();
px.b = (px.b + errPx.b * (1/16)).toInt();
}
}
return pxArr;
}
} }
class Pixel { class Pixel {
@ -81,7 +129,7 @@ class PixelArray {
pixels = new List(height); pixels = new List(height);
for (int y = 0; y < height; y++) { for (int y = 0; y < height; y++) {
pixels[y] = new List(width); pixels[y] = new List(width);
for (int x = 0; x < height; x++) { for (int x = 0; x < width; x++) {
pixels[y][x] = new Pixel(x, y, 0, 0, 0, 0); pixels[y][x] = new Pixel(x, y, 0, 0, 0, 0);
} }
} }
@ -92,7 +140,6 @@ class PixelArray {
int y = 0; int y = 0;
int x = 0; int x = 0;
pixels[y] = new List(imageWidth); pixels[y] = new List(imageWidth);
print(pixels[0].length.toString() + ","+ pixels.length.toString());
for (var pos = 0; pos < array.length; pos = pos + 4) { for (var pos = 0; pos < array.length; pos = pos + 4) {
if (x >= imageWidth) { if (x >= imageWidth) {
x = 0; x = 0;
@ -107,7 +154,7 @@ class PixelArray {
PixelArray.fromImageData(ImageData imagedata, int imageWidth): this.fromByteArray(imagedata.data, imageWidth); PixelArray.fromImageData(ImageData imagedata, int imageWidth): this.fromByteArray(imagedata.data, imageWidth);
PixelArray.fromPixelArray(PixelArray pixelArray) { PixelArray.fromPixelArray(PixelArray pixelArray) {
pixels = new List<List<Pixel>>.from(pixelArray.pixels); pixels = pixelArray.clone().pixels;
} }
Uint8ClampedList toByteArray() { Uint8ClampedList toByteArray() {

4
web/index.html
View file

@ -14,8 +14,8 @@
</head> </head>
<body> <body>
<canvas id="input" width="712" height="470"></canvas> <canvas id="input"></canvas>
<canvas id="output" width="712" height="470"></canvas> <canvas id="output"></canvas>
</body> </body>
</html> </html>

10
web/main.dart
View file

@ -8,11 +8,15 @@ ImageElement inputImg;
ImageElement outputImg; ImageElement outputImg;
void main() { void main() {
inputImg = new ImageElement(src: 'kitten.jpg', width: 712, height: 470); inputImg = new ImageElement(src: 'kitten.jpg');
input = document.querySelector('#input'); input = document.querySelector('#input');
output = document.querySelector('#output'); output = document.querySelector('#output');
input.width = inputImg.width;
input.height = inputImg.height;
output.width = inputImg.width;
output.height = inputImg.height;
inputImg.onLoad.listen(imgLoaded); inputImg.onLoad.listen(imgLoaded);
} }
@ -20,9 +24,9 @@ void imgLoaded(Event e) {
print("image loaded"); print("image loaded");
input.context2D.drawImage(inputImg, 0, 0); input.context2D.drawImage(inputImg, 0, 0);
PixelArray px = new PixelArray.fromImageData(getImageData(input), 712); PixelArray px = new PixelArray.fromImageData(getImageData(input), input.width);
px = Pixed.greyscale(px); px = Pixed.greyscale(px);
px = Pixed.dither(px);
output.context2D.putImageData(px.toImageData(), 0, 0); output.context2D.putImageData(px.toImageData(), 0, 0);
} }