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Less copying in the JPX decoder #4538

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merged 1 commit into from
Apr 16, 2014
+150 −176
Merged

Less copying in the JPX decoder #4538

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1 change: 0 additions & 1 deletion src/core/image.js
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Original file line number Diff line number Diff line change
Expand Up @@ -59,7 +59,6 @@ var PDFImage = (function PDFImageClosure() {
if (dict.has('Filter')) {
var filter = dict.get('Filter').name;
if (filter === 'JPXDecode') {
info('get image params from JPX stream');
var jpxImage = new JpxImage();
jpxImage.parseImageProperties(image.stream);
image.stream.reset();
Expand Down
228 changes: 123 additions & 105 deletions src/core/jpx.js
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Original file line number Diff line number Diff line change
Expand Up @@ -281,7 +281,6 @@ var JpxImage = (function JpxImageClosure() {
cod.entropyCoderWithCustomPrecincts = !!(scod & 1);
cod.sopMarkerUsed = !!(scod & 2);
cod.ephMarkerUsed = !!(scod & 4);
var codingStyle = {};
cod.progressionOrder = data[j++];
cod.layersCount = readUint16(data, j);
j += 2;
Expand Down Expand Up @@ -905,9 +904,15 @@ var JpxImage = (function JpxImageClosure() {
}
return position;
}
function copyCoefficients(coefficients, x0, y0, width, height,
delta, mb, codeblocks, reversible,
segmentationSymbolUsed) {
function copyCoefficients(coefficients, levelWidth, levelHeight, subband,
delta, mb, reversible, segmentationSymbolUsed) {
var x0 = subband.tbx0;
var y0 = subband.tby0;
var width = subband.tbx1 - subband.tbx0;
var codeblocks = subband.codeblocks;
var right = subband.type.charAt(0) === 'H' ? 1 : 0;
var bottom = subband.type.charAt(1) === 'H' ? levelWidth : 0;

for (var i = 0, ii = codeblocks.length; i < ii; ++i) {
var codeblock = codeblocks[i];
var blockWidth = codeblock.tbx1_ - codeblock.tbx0_;
Expand All @@ -921,29 +926,30 @@ var JpxImage = (function JpxImageClosure() {

var bitModel, currentCodingpassType;
bitModel = new BitModel(blockWidth, blockHeight, codeblock.subbandType,
codeblock.zeroBitPlanes);
codeblock.zeroBitPlanes, mb);
currentCodingpassType = 2; // first bit plane starts from cleanup

// collect data
var data = codeblock.data, totalLength = 0, codingpasses = 0;
var q, qq, dataItem;
for (q = 0, qq = data.length; q < qq; q++) {
dataItem = data[q];
var j, jj, dataItem;
for (j = 0, jj = data.length; j < jj; j++) {
dataItem = data[j];
totalLength += dataItem.end - dataItem.start;
codingpasses += dataItem.codingpasses;
}
var encodedData = new Uint8Array(totalLength), k = 0;
for (q = 0, qq = data.length; q < qq; q++) {
dataItem = data[q];
var encodedData = new Uint8Array(totalLength);
var position = 0;
for (j = 0, jj = data.length; j < jj; j++) {
dataItem = data[j];
var chunk = dataItem.data.subarray(dataItem.start, dataItem.end);
encodedData.set(chunk, k);
k += chunk.length;
encodedData.set(chunk, position);
position += chunk.length;
}
// decoding the item
var decoder = new ArithmeticDecoder(encodedData, 0, totalLength);
bitModel.setDecoder(decoder);

for (q = 0; q < codingpasses; q++) {
for (j = 0; j < codingpasses; j++) {
switch (currentCodingpassType) {
case 0:
bitModel.runSignificancePropogationPass();
Expand All @@ -962,13 +968,18 @@ var JpxImage = (function JpxImageClosure() {
}

var offset = (codeblock.tbx0_ - x0) + (codeblock.tby0_ - y0) * width;
var n, nb, position = 0;
var irreversible = !reversible;
var sign = bitModel.coefficentsSign;
var magnitude = bitModel.coefficentsMagnitude;
var bitsDecoded = bitModel.bitsDecoded;
var magnitudeCorrection = reversible ? 0 : 0.5;
for (var j = 0; j < blockHeight; j++) {
var k, n, nb;
position = 0;
// Do the interleaving of Section F.3.3 here, so we do not need
// to copy later. LL level is not interleaved, just copied.
var interleave = (subband.type !== 'LL');
for (j = 0; j < blockHeight; j++) {
var row = (offset / width) | 0; // row in the non-interleaved subband
var levelOffset = 2 * row * (levelWidth - width) + right + bottom;
for (k = 0; k < blockWidth; k++) {
n = magnitude[position];
if (n !== 0) {
Expand All @@ -977,10 +988,11 @@ var JpxImage = (function JpxImageClosure() {
n = -n;
}
nb = bitsDecoded[position];
if (irreversible || mb > nb) {
coefficients[offset] = n * (1 << (mb - nb));
var pos = interleave ? (levelOffset + (offset << 1)) : offset;
if (reversible && (nb >= mb)) {
coefficients[pos] = n;
} else {
coefficients[offset] = n;
coefficients[pos] = n * (1 << (mb - nb));
}
}
offset++;
Expand Down Expand Up @@ -1011,6 +1023,11 @@ var JpxImage = (function JpxImageClosure() {
for (var i = 0; i <= decompositionLevelsCount; i++) {
var resolution = component.resolutions[i];

var width = resolution.trx1 - resolution.trx0;
var height = resolution.try1 - resolution.try0;
// Allocate space for the whole sublevel.
var coefficients = new Float32Array(width * height);

for (var j = 0, jj = resolution.subbands.length; j < jj; j++) {
var mu, epsilon;
if (!scalarExpounded) {
Expand All @@ -1020,31 +1037,30 @@ var JpxImage = (function JpxImageClosure() {
} else {
mu = spqcds[b].mu;
epsilon = spqcds[b].epsilon;
b++;
}

var subband = resolution.subbands[j];
var width = subband.tbx1 - subband.tbx0;
var height = subband.tby1 - subband.tby0;
var gainLog2 = SubbandsGainLog2[subband.type];

// calulate quantization coefficient (Section E.1.1.1)
var delta = (reversible ? 1 :
Math.pow(2, precision + gainLog2 - epsilon) * (1 + mu / 2048));
var mb = (guardBits + epsilon - 1);

var coefficients = new Float32Array(width * height);
copyCoefficients(coefficients, subband.tbx0, subband.tby0,
width, height, delta, mb, subband.codeblocks, reversible,
segmentationSymbolUsed);

subbandCoefficients.push({
width: width,
height: height,
items: coefficients
});

b++;
// In the first resolution level, copyCoefficients will fill the
// whole array with coefficients. In the succeding passes,
// copyCoefficients will consecutively fill in the values that belong
// to the interleaved positions of the HL, LH, and HH coefficients.
// The LL coefficients will then be interleaved in Transform.iterate().
copyCoefficients(coefficients, width, height, subband, delta, mb,
reversible, segmentationSymbolUsed);
}
subbandCoefficients.push({
width: width,
height: height,
items: coefficients
});
}

var result = transform.calculate(subbandCoefficients,
Expand All @@ -1064,60 +1080,80 @@ var JpxImage = (function JpxImageClosure() {
var resultImages = [];
for (var i = 0, ii = context.tiles.length; i < ii; i++) {
var tile = context.tiles[i];
var result = [];
var transformedTiles = [];
var c;
for (c = 0; c < componentsCount; c++) {
var image = transformTile(context, tile, c);
result.push(image);
transformedTiles[c] = transformTile(context, tile, c);
}
var tile0 = transformedTiles[0];
var out = new Uint8Array(tile0.items.length * componentsCount);
var result = {
left: tile0.left,
top: tile0.top,
width: tile0.width,
height: tile0.height,
items: out
};

// Section G.2.2 Inverse multi component transform
var y0items, y1items, y2items, j, jj, y0, y1, y2;
var component, tileImage, items;
var shift, offset, max, min;
var pos = 0, j, jj, y0, y1, y2, r, g, b, val;
if (tile.codingStyleDefaultParameters.multipleComponentTransform) {
var y2items = transformedTiles[2].items;
var y1items = transformedTiles[1].items;
var y0items = transformedTiles[0].items;

// HACK: The multiple component transform formulas below assume that
// all components have the same precision. With this in mind, we
// compute shift and offset only once.
shift = components[0].precision - 8;
offset = (128 << shift) + 0.5;
max = (127.5 * (1 << shift));
min = -max;

var component0 = tile.components[0];
if (!component0.codingStyleParameters.reversibleTransformation) {
// inverse irreversible multiple component transform
y0items = result[0].items;
y1items = result[1].items;
y2items = result[2].items;
for (j = 0, jj = y0items.length; j < jj; ++j) {
y0 = y0items[j] + 0.5; y1 = y1items[j]; y2 = y2items[j];
y0items[j] = y0 + 1.402 * y2;
y1items[j] = y0 - 0.34413 * y1 - 0.71414 * y2;
y2items[j] = y0 + 1.772 * y1;
y0 = y0items[j];
y1 = y1items[j];
y2 = y2items[j];
r = y0 + 1.402 * y2;
g = y0 - 0.34413 * y1 - 0.71414 * y2;
b = y0 + 1.772 * y1;
out[pos++] = r <= min ? 0 : r >= max ? 255 : (r + offset) >> shift;
out[pos++] = g <= min ? 0 : g >= max ? 255 : (g + offset) >> shift;
out[pos++] = b <= min ? 0 : b >= max ? 255 : (b + offset) >> shift;
}
} else {
// inverse reversible multiple component transform
y0items = result[0].items;
y1items = result[1].items;
y2items = result[2].items;
for (j = 0, jj = y0items.length; j < jj; ++j) {
y0 = y0items[j]; y1 = y1items[j]; y2 = y2items[j];
var i1 = y0 - ((y2 + y1) >> 2);
y1items[j] = i1;
y0items[j] = y2 + i1;
y2items[j] = y1 + i1;
y0 = y0items[j];
y1 = y1items[j];
y2 = y2items[j];
g = y0 - ((y2 + y1) >> 2);
r = g + y2;
b = g + y1;
out[pos++] = r <= min ? 0 : r >= max ? 255 : (r + offset) >> shift;
out[pos++] = g <= min ? 0 : g >= max ? 255 : (g + offset) >> shift;
out[pos++] = b <= min ? 0 : b >= max ? 255 : (b + offset) >> shift;
}
}
}

// To simplify things: shift and clamp output to 8 bit unsigned
for (c = 0; c < componentsCount; c++) {
component = components[c];
var shift = component.precision - 8;
tileImage = result[c];
items = tileImage.items;
var data = new Uint8Array(items.length);
var low = -(128 << shift);
var high = 127 << shift;
for (j = 0, jj = items.length; j < jj; j++) {
var val = items[j];
data[j] = val <= low ? 0 : val >= high ? 255 : (val >> shift) + 128;
} else { // no multi-component transform
for (c = 0; c < componentsCount; c++) {
var items = transformedTiles[c].items;
shift = components[c].precision - 8;
offset = (128 << shift) + 0.5;
max = (127.5 * (1 << shift));
min = -max;
for (pos = c, j = 0, jj = items.length; j < jj; j++) {
val = items[j];
out[pos] = val <= min ? 0 :
val >= max ? 255 : (val + offset) >> shift;
pos += componentsCount;
}
}
result[c].items = data;
}

resultImages.push(result);
}
return resultImages;
Expand Down Expand Up @@ -1302,7 +1338,7 @@ var JpxImage = (function JpxImageClosure() {
8, 0, 8, 8, 8, 0, 8, 8, 8, 0, 0, 0, 0, 0, 8, 8, 8, 0, 8, 8, 8, 0, 8, 8, 8
]);

function BitModel(width, height, subband, zeroBitPlanes) {
function BitModel(width, height, subband, zeroBitPlanes, mb) {
this.width = width;
this.height = height;

Expand All @@ -1315,7 +1351,9 @@ var JpxImage = (function JpxImageClosure() {
// add border state cells for significanceState
this.neighborsSignificance = new Uint8Array(coefficientCount);
this.coefficentsSign = new Uint8Array(coefficientCount);
this.coefficentsMagnitude = new Uint32Array(coefficientCount);
this.coefficentsMagnitude = mb > 14 ? new Uint32Array(coefficientCount) :
mb > 6 ? new Uint16Array(coefficientCount) :
new Uint8Array(coefficientCount);
this.processingFlags = new Uint8Array(coefficientCount);

var bitsDecoded = new Uint8Array(coefficientCount);
Expand Down Expand Up @@ -1628,9 +1666,8 @@ var JpxImage = (function JpxImageClosure() {
Transform.prototype.calculate =
function transformCalculate(subbands, u0, v0) {
var ll = subbands[0];
for (var i = 1, ii = subbands.length; i < ii; i += 3) {
ll = this.iterate(ll, subbands[i], subbands[i + 1],
subbands[i + 2], u0, v0);
for (var i = 1, ii = subbands.length; i < ii; i++) {
ll = this.iterate(ll, subbands[i], u0, v0);
}
return ll;
};
Expand All @@ -1647,43 +1684,24 @@ var JpxImage = (function JpxImageClosure() {
buffer[i1] = buffer[j1];
buffer[j2] = buffer[i2];
};
Transform.prototype.iterate = function Transform_iterate(ll, hl, lh, hh,
u0, v0) {
var llWidth = ll.width, llHeight = ll.height, llItems = ll.items;
var hlWidth = hl.width, hlHeight = hl.height, hlItems = hl.items;
var lhWidth = lh.width, lhHeight = lh.height, lhItems = lh.items;
var hhWidth = hh.width, hhHeight = hh.height, hhItems = hh.items;
Transform.prototype.iterate = function Transform_iterate(ll, hl_lh_hh,
u0, v0) {

// Section F.3.3 interleave
var width = llWidth + hlWidth;
var height = llHeight + lhHeight;
var items = new Float32Array(width * height);
var i, j, k, l, v, u;
var llWidth = ll.width, llHeight = ll.height, llItems = ll.items;
var width = hl_lh_hh.width;
var height = hl_lh_hh.height;
var items = hl_lh_hh.items;
var i, j, k, l, u, v;

for (i = 0, k = 0; i < llHeight; i++) {
// Interleave LL according to Section F.3.3
for (k = 0, i = 0; i < llHeight; i++) {
l = i * 2 * width;
for (j = 0; j < llWidth; j++, k++, l += 2) {
items[l] = llItems[k];
}
}
for (i = 0, k = 0; i < hlHeight; i++) {
l = i * 2 * width + 1;
for (j = 0; j < hlWidth; j++, k++, l += 2) {
items[l] = hlItems[k];
}
}
for (i = 0, k = 0; i < lhHeight; i++) {
l = (i * 2 + 1) * width;
for (j = 0; j < lhWidth; j++, k++, l += 2) {
items[l] = lhItems[k];
}
}
for (i = 0, k = 0; i < hhHeight; i++) {
l = (i * 2 + 1) * width + 1;
for (j = 0; j < hhWidth; j++, k++, l += 2) {
items[l] = hhItems[k];
}
}
// The LL band is not needed anymore.
llItems = ll.items = null;

var bufferPadding = 4;
var rowBuffer = new Float32Array(width + 2 * bufferPadding);
Expand Down
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