Merge branch 'dithering-algorithm'

create PixelArray from another PixelArray
create empty PixelArray
convert PixelArray to ImageData

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2018 Marty Oehme
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

LICENSE.md

@@ -1,2 +0,0 @@
-
-Copyright (C) 2018 

lib/Dither.dart

@@ -1,18 +1,223 @@
 import 'dart:html';
+import 'dart:typed_data';
 
-class Dither {
-  static ImageData editImage(ImageData image) {
+class Pixed {
+  static PixelArray greyscale(PixelArray image) {
+    PixelArray pxArr = new PixelArray.fromPixelArray(image);
 
+    for (var y = 0; y < pxArr.getHeight(); y++) {
+      for (var x = 0; x < pxArr.getWidth(); x++) {
+        var px = pxArr.getPixel(x, y);
+        int average = ((px.r+px.g+px.b) / 3).round();
+        px.r = average;
+        px.g = average;
+        px.b = average;
+      }
+    }
+    return pxArr;
+  }
 
-//  image = contrast( image, 200);
+  static PixelArray quantize(PixelArray image, [int steps=1]) {
+    PixelArray pxArr = new PixelArray.fromPixelArray(image);
+    for (var y = 0; y < pxArr.getHeight(); y++) {
+      for (var x = 0; x < pxArr.getWidth(); x++) {
+        pxArr.setPixel( _quantizePixel(pxArr.getPixel(x, y)) );
+      }
+    }
+    return pxArr;
+  }
 
-    for (var y = 0; y < image.height; y++) {
-      for (var x = 0; x < image.width; x++) {
-//      print(image.getPixel(x, y));
+  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);
+    for (var y = 0; y < pxArr.getHeight(); y++) {
+      for (var x = 0; x < pxArr.getWidth(); x++) {
+        Pixel px = pxArr.getPixel(x, y);
+        Pixel quant = quantized.getPixel(x, y);
+        px.r = px.r - quant.r;
+        px.g = px.g - quant.g;
+        px.b = px.b - quant.b;
+      }
+    }
+    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;
   }
 }
 
-    return image;
+class Pixel {
+  int x;
+  int y;
+  int r;
+  int g;
+  int b;
+  int a;
+
+  Pixel(this.x, this.y, this.r, this.g, this.b, this.a);
+
+  int getBytePos(int imageWidth) {
+    return (x+y*imageWidth)*4;
   }
 
+  void setRGB(int r, int g, int b) {
+    this.r = r;
+    this.g = g;
+    this.b = b;
+  }
+
+  @override
+  String toString() {
+    return 'Pixel at $x, $y: {r: $r, g: $g, b: $b, a: $a}';
+  }
+
+
+}
+
+class PixelArray {
+  //TODO Implement iterable
+  List<List<Pixel>> pixels;
+
+  PixelArray(int width, int height) {
+    pixels = new List(height);
+    for (int y = 0; y < height; y++) {
+      pixels[y] = new List(width);
+      for (int x = 0; x < width; x++) {
+        pixels[y][x] = new Pixel(x, y, 0, 0, 0, 0);
+      }
+    }
+  }
+
+  PixelArray.fromByteArray(Uint8ClampedList array, int imageWidth) {
+    pixels = new List(array.length~/imageWidth~/4);
+    int y = 0;
+    int x = 0;
+    pixels[y] = new List(imageWidth);
+    for (var pos = 0; pos < array.length; pos = pos + 4) {
+      if (x >= imageWidth) {
+        x = 0;
+        y++;
+        pixels[y] = new List(imageWidth);
+      }
+      pixels[y][x] = new Pixel(x, y, array[pos], array[pos+1], array[pos+2], array[pos+3]);
+      x++;
+    }
+  }
+
+  PixelArray.fromImageData(ImageData imagedata, int imageWidth): this.fromByteArray(imagedata.data, imageWidth);
+
+  PixelArray.fromPixelArray(PixelArray pixelArray) {
+    pixels = pixelArray.clone().pixels;
+  }
+
+  Uint8ClampedList toByteArray() {
+    //TODO: look for longest array, or each line separately. Only gets width from line 1 currently.
+    Uint8ClampedList result = new Uint8ClampedList(getHeight()*getWidth()*4);
+    int x = 0;
+    int y = 0;
+    for (var i = 0; i < result.length; i = i + 4) {
+      if (x >= getWidth()) {
+        y++;
+        x = 0;
+      }
+      result[i] = pixels[y][x].r;
+      result[i+1] = pixels[y][x].g;
+      result[i+2] = pixels[y][x].b;
+      result[i+3] = pixels[y][x].a;
+
+      x++;
+    }
+
+    return result;
+  }
+
+  ImageData toImageData() {
+    return new ImageData(this.toByteArray(), this.getWidth(), this.getHeight());
+  }
+
+  Pixel getPixel(int x, int y) {
+    return pixels[y][x];
+  }
+
+  void setPixel(Pixel pixel, [int x, int y]) {
+    if (x != null && y != null && getHeight() < y && getWidth() < x) {
+      pixel.x = x;
+      pixel.y = y;
+      pixels[y][x] = pixel;
+      return;
+    } else if (getHeight() <= pixel.y || getWidth() <= pixel.x) {
+      return;
+    } else {
+      pixels[pixel.y][pixel.x] = pixel;
+      return;
+    }
+  }
+
+  int getWidth() {
+    //TODO find longest/shortest width not at 0 (support for non square img)
+    return pixels[0].length;
+  }
+
+  int getHeight() {
+    return pixels.length;
+  }
+
+  PixelArray clone() {
+    PixelArray pxArr = new PixelArray(getWidth(), getHeight());
+    for (var y = 0; y < getHeight(); y++) {
+      for (var x = 0; x < getWidth(); x++) {
+        Pixel px = getPixel(x, y);
+        Pixel newPix = new Pixel(x, y, px.r, px.g, px.b, px.a);
+        pxArr.setPixel( newPix, x, y );
+      }
+    }
+    return pxArr;
+  }
 }

web/index.html

@@ -14,8 +14,8 @@
 </head>
 
 <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>
 </html>

web/main.dart

@@ -8,11 +8,15 @@ ImageElement inputImg;
 ImageElement outputImg;
 
 void main() {
-  inputImg = new ImageElement(src: 'kitten.jpg', width: 712, height: 470);
+  inputImg = new ImageElement(src: 'kitten.jpg');
 
   input = document.querySelector('#input');
   output = document.querySelector('#output');
 
+  input.width = inputImg.width;
+  input.height = inputImg.height;
+  output.width = inputImg.width;
+  output.height = inputImg.height;
   inputImg.onLoad.listen(imgLoaded);
 }
 
@@ -20,7 +24,10 @@ void imgLoaded(Event e) {
   print("image loaded");
   input.context2D.drawImage(inputImg, 0, 0);
 
-  output.context2D.putImageData( Dither.editImage( getImageData(input)), 0, 0);
+  PixelArray px = new PixelArray.fromImageData(getImageData(input), input.width);
+  px = Pixed.greyscale(px);
+  px = Pixed.dither(px);
+  output.context2D.putImageData(px.toImageData(), 0, 0);
 }
 
 ImageData getImageData(CanvasElement canvas) {

web/styles.css

@@ -6,11 +6,11 @@ html, body {
   margin: 0;
   padding: 0;
   font-family: 'Roboto', sans-serif;
-  background: gainsboro;
+  background: black;
 }
 
 canvas {
-  padding: 00px;
+  padding: 0px;
   text-align: center;
 }