mirror of
https://github.com/konvajs/konva.git
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73 lines
2.2 KiB
JavaScript
73 lines
2.2 KiB
JavaScript
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(function () {
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function remap(fromValue, fromMin, fromMax, toMin, toMax) {
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// Compute the range of the data
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var fromRange = fromMax - fromMin,
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toRange = toMax - toMin,
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toValue;
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// If either range is 0, then the value can only be mapped to 1 value
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if (fromRange === 0) {
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return toMin + toRange / 2;
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}
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if (toRange === 0) {
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return toMin;
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}
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// (1) untranslate, (2) unscale, (3) rescale, (4) retranslate
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toValue = (fromValue - fromMin) / fromRange;
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toValue = (toRange * toValue) + toMin;
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return toValue;
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}
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/**
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* Enhance Filter. Adjusts the colors so that they span the widest
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* possible range (ie 0-255). Performs w*h pixel reads and w*h pixel
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* writes.
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* @function
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* @memberof Kinetic.Filters
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* @param {Object} imageData
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* @author ippo615
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*/
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Kinetic.Filters.Enhance = function (imageData) {
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var data = imageData.data,
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nPixels = data.length,
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rMin = data[0], rMax = rMin, r,
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gMin = data[1], gMax = gMin, g,
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bMin = data[3], bMax = bMin, b,
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aMin = data[4], aMax = aMin, a,
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i;
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// 1st Pass - find the min and max for each channel:
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for (i = 0; i < nPixels; i += 4) {
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r = data[i + 0];
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if (r < rMin) { rMin = r; } else
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if (r > rMax) { rMax = r; }
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g = data[i + 1];
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if (g < gMin) { gMin = g; } else
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if (g > gMax) { gMax = g; }
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b = data[i + 2];
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if (b < bMin) { bMin = b; } else
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if (b > bMax) { bMax = b; }
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a = data[i + 3];
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if (a < aMin) { aMin = a; } else
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if (a > aMax) { aMax = a; }
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}
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// If there is only 1 level - don't remap
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if( rMax === rMin ){ rMax = 255; rMin = 0; }
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if( gMax === gMin ){ gMax = 255; gMin = 0; }
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if( bMax === bMin ){ bMax = 255; bMin = 0; }
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if( aMax === aMin ){ aMax = 255; aMin = 0; }
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// Pass 2 - remap everything to fill the full range
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for (i = 0; i < nPixels; i += 1) {
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data[i + 0] = remap(data[i + 0], rMin, rMax, 0, 255);
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data[i + 1] = remap(data[i + 1], gMin, gMax, 0, 255);
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data[i + 2] = remap(data[i + 2], bMin, bMax, 0, 255);
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data[i + 3] = remap(data[i + 3], aMin, aMax, 0, 255);
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}
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};
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})();
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