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Fixes #34 (Diff swallows black color in added areas): adds options.ligth... #52

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Fixes #34 (Diff swallows black color in added areas): adds options.ligth... #52

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54fe17a
Fixes #34 (Diff swallows black color in added areas): adds options.li…
B2F Apr 18, 2015
491f867
Replaces lightness and rgb options with lightboost and diffColor (PR …
B2F May 14, 2015
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49 changes: 41 additions & 8 deletions imagediff.js
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -194,10 +194,12 @@
i, j, k, v;

for (i = 0; i < length; i += 4) {
cData[i] = Math.abs(aData[i] - bData[i]);
cData[i+1] = Math.abs(aData[i+1] - bData[i+1]);
cData[i+2] = Math.abs(aData[i+2] - bData[i+2]);
cData[i+3] = Math.abs(255 - Math.abs(aData[i+3] - bData[i+3]));
var pixelA = Array.prototype.slice.call(aData, i, i+3);
var pixelB = Array.prototype.slice.call(bData, i, i+3);
var pixelC = diffPixels(pixelA, pixelB, options);
for (var rgbIndex = 0; rgbIndex < 4; rgbIndex++) {
cData[i+rgbIndex] = pixelC[rgbIndex];
}
}

return c;
Expand Down Expand Up @@ -231,7 +233,6 @@
cData[i+0] = aData[j+0]; // r
cData[i+1] = aData[j+1]; // g
cData[i+2] = aData[j+2]; // b
// cData[i+3] = aData[j+3]; // a
}
}

Expand All @@ -241,9 +242,12 @@
for (column = b.width; column--;) {
i = 4 * ((row + rowOffset) * width + (column + columnOffset));
j = 4 * (row * b.width + column);
cData[i+0] = Math.abs(cData[i+0] - bData[j+0]); // r
cData[i+1] = Math.abs(cData[i+1] - bData[j+1]); // g
cData[i+2] = Math.abs(cData[i+2] - bData[j+2]); // b
var pixelA = Array.prototype.slice.call(cData, i, i+3);
var pixelB = Array.prototype.slice.call(bData, j, j+3);
var pixelC = diffPixels(pixelA, pixelB, options);
for (var rgbIndex = 0; rgbIndex < 4; rgbIndex++) {
cData[i+rgbIndex] = pixelC[rgbIndex];
}
}
}

Expand All @@ -261,6 +265,35 @@
return c;
}

/**
* Differentiates two rgb pixels by subtracting color values.
* @see https://github.com/HumbleSoftware/js-imagediff/pull/52
*
* @param {Object} options
* options.lightboost: increases differences visibility with a light boost.
* options.diffColor: a rgb array used to specify differences color instead of light gap.
* options.stack: stacks differences on top of the original image, preserving common pixels.
*
* @returns {Array} pixel rgba values between 0 and 255.
*/
function diffPixels(pixelA, pixelB, options) {
var lightboost = options && options.lightboost || 0;
var diffColor = options && options.diffColor || false;
var stack = options && options.stack || false;
// pixel = [r,g,b,a]
var pixelC = [0,0,0,255];
for (var rgbIndex = 0; rgbIndex < 3 ; rgbIndex++) {
pixelC[rgbIndex] = Math.abs(pixelA[rgbIndex] - pixelB[rgbIndex]);
if (pixelC[rgbIndex] > 0) {
if (diffColor) pixelC[rgbIndex] = diffColor[rgbIndex];
pixelC[rgbIndex] = Math.min(pixelC[rgbIndex] + lightboost, 255);
}
else if (stack) {
pixelC[rgbIndex] = pixelA[rgbIndex];
}
}
return pixelC;
}

// Validation
function checkType () {
Expand Down
49 changes: 41 additions & 8 deletions js/imagediff.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -187,10 +187,12 @@
i, j, k, v;

for (i = 0; i < length; i += 4) {
cData[i] = Math.abs(aData[i] - bData[i]);
cData[i+1] = Math.abs(aData[i+1] - bData[i+1]);
cData[i+2] = Math.abs(aData[i+2] - bData[i+2]);
cData[i+3] = Math.abs(255 - Math.abs(aData[i+3] - bData[i+3]));
var pixelA = Array.prototype.slice.call(aData, i, i+3);
var pixelB = Array.prototype.slice.call(bData, i, i+3);
var pixelC = diffPixels(pixelA, pixelB, options);
for (var rgbIndex = 0; rgbIndex < 4; rgbIndex++) {
cData[i+rgbIndex] = pixelC[rgbIndex];
}
}

return c;
Expand Down Expand Up @@ -224,7 +226,6 @@
cData[i+0] = aData[j+0]; // r
cData[i+1] = aData[j+1]; // g
cData[i+2] = aData[j+2]; // b
// cData[i+3] = aData[j+3]; // a
}
}

Expand All @@ -234,9 +235,12 @@
for (column = b.width; column--;) {
i = 4 * ((row + rowOffset) * width + (column + columnOffset));
j = 4 * (row * b.width + column);
cData[i+0] = Math.abs(cData[i+0] - bData[j+0]); // r
cData[i+1] = Math.abs(cData[i+1] - bData[j+1]); // g
cData[i+2] = Math.abs(cData[i+2] - bData[j+2]); // b
var pixelA = Array.prototype.slice.call(cData, i, i+3);
var pixelB = Array.prototype.slice.call(bData, j, j+3);
var pixelC = diffPixels(pixelA, pixelB, options);
for (var rgbIndex = 0; rgbIndex < 4; rgbIndex++) {
cData[i+rgbIndex] = pixelC[rgbIndex];
}
}
}

Expand All @@ -254,6 +258,35 @@
return c;
}

/**
* Differentiates two rgb pixels by subtracting color values.
* @see https://github.com/HumbleSoftware/js-imagediff/pull/52
*
* @param {Object} options
* options.lightboost: increases differences visibility with a light boost.
* options.diffColor: a rgb array used to specify differences color instead of light gap.
* options.stack: stacks differences on top of the original image, preserving common pixels.
*
* @returns {Array} pixel rgba values between 0 and 255.
*/
function diffPixels(pixelA, pixelB, options) {
var lightboost = options && options.lightboost || 0;
var diffColor = options && options.diffColor || false;
var stack = options && options.stack || false;
// pixel = [r,g,b,a]
var pixelC = [0,0,0,255];
for (var rgbIndex = 0; rgbIndex < 3 ; rgbIndex++) {
pixelC[rgbIndex] = Math.abs(pixelA[rgbIndex] - pixelB[rgbIndex]);
if (pixelC[rgbIndex] > 0) {
if (diffColor) pixelC[rgbIndex] = diffColor[rgbIndex];
pixelC[rgbIndex] = Math.min(pixelC[rgbIndex] + lightboost, 255);
}
else if (stack) {
pixelC[rgbIndex] = pixelA[rgbIndex];
}
}
return pixelC;
}

// Validation
function checkType () {
Expand Down
49 changes: 47 additions & 2 deletions spec/ImageDiffSpec.js
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -312,14 +312,29 @@ describe('ImageUtils', function() {
});

it('should calculate difference', function () {
a = imagediff.createImageData(1, 1),
a.data[1] = 200,
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semicolon instead of a comma at the end of the line? I haven't come across this syntax before.

b = imagediff.createImageData(1, 1),
b.data[1] = 158,
c = imagediff.diff(a, b),

d = imagediff.createImageData(1, 1);
d.data[1] = 42;
d.data[3] = 255;

expect(c).toImageDiffEqual(d);
});

it('should calculate color difference with adjusted lightness', function () {
a = imagediff.createImageData(1, 1),
a.data[1] = 200;
b = imagediff.createImageData(1, 1),
b.data[1] = 158;
c = imagediff.diff(a, b);
c = imagediff.diff(a, b, {lightboost: 155});

d = imagediff.createImageData(1, 1);
d.data[1] = 42;
// a-b + 155
d.data[1] = 197;
d.data[3] = 255;

expect(c).toImageDiffEqual(d);
Expand Down Expand Up @@ -361,6 +376,36 @@ describe('ImageUtils', function() {

expect(c).toImageDiffEqual(d);
});

it('should optionally color differences', function () {
a = imagediff.createImageData(1, 1),
b = imagediff.createImageData(1, 1);
// Fills a grey pixel and expects c to be tinted in light pink
Array.prototype.forEach.call(b.data, function (value, i) {
b.data[i] = 125;
});
c = imagediff.diff(a, b, {diffColor: [255,0,44], lightboost: 191});

d = imagediff.createImageData(1, 1);
d.data[0] = 255;
d.data[1] = 191;
d.data[2] = 235;
d.data[3] = 255;

expect(c).toImageDiffEqual(d);
});

it('should optionally show common pixels', function () {
a = imagediff.createImageData(1, 1);
// Fills white pixels
Array.prototype.forEach.call(a.data, function (value, i) {
a.data[i] = 255;
});
b = a;
c = imagediff.diff(a, b, {stack: true});

expect(c).toImageDiffEqual(a);
});
});

/*
Expand Down