Merge pull request #4600 from p01/JPX_optimization_2
Optimized JPX decoder ~6% faster
This commit is contained in:
Yury Delendik
commit
ead4cbf2b7
108
src/core/jpx.js
108
src/core/jpx.js
@ -954,7 +954,7 @@ var JpxImage = (function JpxImageClosure() {
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var magnitudeCorrection = reversible ? 0 : 0.5;
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var k, n, nb;
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position = 0;
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// Do the interleaving of Section F.3.3 here, so we do not need
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// Do the interleaving of Section F.3.3 here, so we do not need
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// to copy later. LL level is not interleaved, just copied.
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var interleave = (subband.type !== 'LL');
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for (j = 0; j < blockHeight; j++) {
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@ -1566,12 +1566,16 @@ var JpxImage = (function JpxImageClosure() {
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var oneRowDown = width;
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var twoRowsDown = width * 2;
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var threeRowsDown = width * 3;
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for (var i0 = 0; i0 < height; i0 += 4) {
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var iNext;
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for (var i0 = 0; i0 < height; i0 = iNext) {
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iNext = Math.min(i0 + 4, height);
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var indexBase = i0 * width;
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var checkAllEmpty = i0 + 3 < height;
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for (var j = 0; j < width; j++) {
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var index0 = i0 * width + j;
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var index0 = indexBase + j;
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// using the property: labels[neighborsSignificance[index]] == 0
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// when neighborsSignificance[index] == 0
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var allEmpty = (i0 + 3 < height &&
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var allEmpty = (checkAllEmpty &&
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processingFlags[index0] === 0 &&
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processingFlags[index0 + oneRowDown] === 0 &&
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processingFlags[index0 + twoRowsDown] === 0 &&
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@ -1581,7 +1585,7 @@ var JpxImage = (function JpxImageClosure() {
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neighborsSignificance[index0 + twoRowsDown] === 0 &&
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neighborsSignificance[index0 + threeRowsDown] === 0);
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var i1 = 0, index = index0;
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var i, sign;
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var i = i0, sign;
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if (allEmpty) {
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var hasSignificantCoefficent =
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decoder.readBit(contexts, RUNLENGTH_CONTEXT);
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@ -1594,8 +1598,10 @@ var JpxImage = (function JpxImageClosure() {
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}
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i1 = (decoder.readBit(contexts, UNIFORM_CONTEXT) << 1) |
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decoder.readBit(contexts, UNIFORM_CONTEXT);
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i = i0 + i1;
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index += i1 * width;
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if (i1 !== 0) {
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i = i0 + i1;
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index += i1 * width;
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}
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sign = this.decodeSignBit(i, j, index);
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coefficentsSign[index] = sign;
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@ -1610,12 +1616,7 @@ var JpxImage = (function JpxImageClosure() {
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i1++;
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}
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for (; i1 < 4; i1++, index += width) {
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i = i0 + i1;
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if (i >= height) {
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break;
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}
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for (i = i0 + i1; i < iNext; i++, index += width) {
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if (coefficentsMagnitude[index] ||
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(processingFlags[index] & processedMask) !== 0) {
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continue;
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@ -1623,7 +1624,7 @@ var JpxImage = (function JpxImageClosure() {
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var contextLabel = labels[neighborsSignificance[index]];
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var decision = decoder.readBit(contexts, contextLabel);
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if (decision == 1) {
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if (decision === 1) {
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sign = this.decodeSignBit(i, j, index);
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coefficentsSign[index] = sign;
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coefficentsMagnitude[index] = 1;
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@ -1678,7 +1679,6 @@ var JpxImage = (function JpxImageClosure() {
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};
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Transform.prototype.iterate = function Transform_iterate(ll, hl_lh_hh,
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u0, v0) {
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var llWidth = ll.width, llHeight = ll.height, llItems = ll.items;
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var width = hl_lh_hh.width;
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var height = hl_lh_hh.height;
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@ -1711,7 +1711,7 @@ var JpxImage = (function JpxImageClosure() {
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rowBuffer.set(items.subarray(k, k + width), bufferPadding);
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this.extend(rowBuffer, bufferPadding, width);
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this.filter(rowBuffer, bufferPadding, width, u0, rowBuffer);
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this.filter(rowBuffer, bufferPadding, width);
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items.set(
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rowBuffer.subarray(bufferPadding, bufferPadding + width),
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@ -1757,7 +1757,7 @@ var JpxImage = (function JpxImageClosure() {
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currentBuffer--;
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var buffer = colBuffers[currentBuffer];
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this.extend(buffer, bufferPadding, height);
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this.filter(buffer, bufferPadding, height, v0, buffer);
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this.filter(buffer, bufferPadding, height);
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// If this is last buffer in this group of buffers, flush all buffers.
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if (currentBuffer === 0) {
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@ -1788,9 +1788,10 @@ var JpxImage = (function JpxImageClosure() {
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IrreversibleTransform.prototype = Object.create(Transform.prototype);
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IrreversibleTransform.prototype.filter =
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function irreversibleTransformFilter(y, offset, length, i0, x) {
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function irreversibleTransformFilter(x, offset, length) {
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var len = length >> 1;
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offset = offset | 0;
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var j, n, current, next;
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var alpha = -1.586134342059924;
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var beta = -0.052980118572961;
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@ -1798,34 +1799,75 @@ var JpxImage = (function JpxImageClosure() {
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var delta = 0.443506852043971;
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var K = 1.230174104914001;
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var K_ = 1 / K;
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var j, n;
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// step 1 is combined with step 3
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// step 2
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for (j = offset - 3, n = len + 4; n--; j += 2) {
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x[j] = K_ * y[j];
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j = offset - 3;
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for (n = len + 4; n--; j += 2) {
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x[j] *= K_;
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}
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// step 1 & 3
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for (j = offset - 2, n = len + 3; n--; j += 2) {
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x[j] = K * y[j] -
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delta * (x[j - 1] + x[j + 1]);
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j = offset - 2;
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current = delta * x[j -1];
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for (n = len + 3; n--; j += 2) {
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next = delta * x[j + 1];
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x[j] = K * x[j] - current - next;
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if (n--) {
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j += 2;
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current = delta * x[j + 1];
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x[j] = K * x[j] - current - next;
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} else {
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break;
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}
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}
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// step 4
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for (j = offset - 1, n = len + 2; n--; j += 2) {
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x[j] -= gamma * (x[j - 1] + x[j + 1]);
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j = offset - 1;
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current = gamma * x[j - 1];
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for (n = len + 2; n--; j += 2) {
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next = gamma * x[j + 1];
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x[j] -= current + next;
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if (n--) {
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j += 2;
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current = gamma * x[j + 1];
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x[j] -= current + next;
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} else {
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break;
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}
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}
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// step 5
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for (j = offset, n = len + 1; n--; j += 2) {
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x[j] -= beta * (x[j - 1] + x[j + 1]);
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j = offset;
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current = beta * x[j - 1];
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for (n = len + 1; n--; j += 2) {
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next = beta * x[j + 1];
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x[j] -= current + next;
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if (n--) {
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j += 2;
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current = beta * x[j + 1];
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x[j] -= current + next;
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} else {
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break;
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}
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}
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// step 6
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for (j = offset + 1, n = len; n--; j += 2) {
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x[j] -= alpha * (x[j - 1] + x[j + 1]);
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if (len !== 0) {
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j = offset + 1;
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current = alpha * x[j - 1];
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for (n = len; n--; j += 2) {
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next = alpha * x[j + 1];
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x[j] -= current + next;
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if (n--) {
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j += 2;
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current = alpha * x[j + 1];
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x[j] -= current + next;
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} else {
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break;
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}
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}
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}
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};
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@ -1840,17 +1882,17 @@ var JpxImage = (function JpxImageClosure() {
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ReversibleTransform.prototype = Object.create(Transform.prototype);
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ReversibleTransform.prototype.filter =
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function reversibleTransformFilter(y, offset, length, i0, x) {
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function reversibleTransformFilter(x, offset, length) {
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var len = length >> 1;
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offset = offset | 0;
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var j, n;
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for (j = offset, n = len + 1; n--; j += 2) {
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x[j] = y[j] - ((y[j - 1] + y[j + 1] + 2) >> 2);
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x[j] -= (x[j - 1] + x[j + 1] + 2) >> 2;
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}
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for (j = offset + 1, n = len; n--; j += 2) {
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x[j] = y[j] + ((x[j - 1] + x[j + 1]) >> 1);
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x[j] += (x[j - 1] + x[j + 1]) >> 1;
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}
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};
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