578 lines
21 KiB
JavaScript
578 lines
21 KiB
JavaScript
/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- /
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/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */
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// - The JPEG specification can be found in the ITU CCITT Recommendation T.81
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// (www.w3.org/Graphics/JPEG/itu-t81.pdf)
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// - The JFIF specification can be found in the JPEG File Interchange Format
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// (www.w3.org/Graphics/JPEG/jfif3.pdf)
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// - The Adobe Application-Specific JPEG markers in the Supporting the DCT Filters
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// in PostScript Level 2, Technical Note #5116
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// (partners.adobe.com/public/developer/en/ps/sdk/5116.DCT_Filter.pdf)
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var JpegImage = (function() {
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function constructor() {
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}
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var iDCTTables = (function() {
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var cosTables = [], i, j;
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for (i = 0; i < 8; i++) {
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cosTables.push(new Float32Array(8));
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for (j = 0; j < 8; j++)
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cosTables[i][j] = Math.cos((2 * i + 1) * j * Math.PI / 16) *
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(j > 0 ? 1 : 1/Math.sqrt(2));
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}
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var x, y, u, v;
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var tables = [];
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for (y = 0; y < 8; y++) {
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var cosTable_y = cosTables[y];
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for (x = 0; x < 8; x++) {
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var cosTable_x = cosTables[x];
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var table = new Float32Array(64);
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i = 0;
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for (v = 0; v < 8; v++) {
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for (u = 0; u < 8; u++)
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table[i++] = cosTable_x[u] * cosTable_y[v];
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}
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tables.push(table);
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}
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}
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return tables;
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})();
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function buildHuffmanTable(codeLengths, values) {
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var k = 0, code = [], i, j, length = 16;
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while (length > 0 && !codeLengths[length - 1])
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length--;
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code.push({children: [], index: 0});
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var p = code[0], q;
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for (i = 0; i < length; i++) {
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for (j = 0; j < codeLengths[i]; j++) {
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p = code.pop();
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p.children[p.index] = values[k];
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while (p.index > 0) {
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p = code.pop();
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}
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p.index++;
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code.push(p);
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while (code.length <= i) {
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code.push(q = {children: [], index: 0});
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p.children[p.index] = q.children;
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p = q;
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}
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k++;
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}
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if (i + 1 < length) {
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// p here points to last code
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code.push(q = {children: [], index: 0});
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p.children[p.index] = q.children;
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p = q;
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}
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}
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return code[0].children;
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}
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function decodeScan(data, offset,
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frame, components, resetInterval,
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spectralStart, spectralEnd,
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successivePrev, successive) {
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var precision = frame.precision;
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var samplesPerLine = frame.samplesPerLine;
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var scanLines = frame.scanLines;
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var progressive = frame.progressive;
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var maxH = frame.maxH, maxV = frame.maxV;
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var startOffset = offset, bitsData = 0, bitsCount = 0;
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function readBit() {
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if (bitsCount > 0) {
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bitsCount--;
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return (bitsData >> bitsCount) & 1;
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}
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bitsData = data[offset++];
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if (bitsData == 0xFF) {
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var nextByte = data[offset++];
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if (nextByte) {
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throw "unexpected marker: " + ((bitsData << 8) | nextByte).toString(16);
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}
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// unstuff 0
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}
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bitsCount = 7;
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return bitsData >>> 7;
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}
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function decodeHuffman(tree) {
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var node = tree, bit;
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while ((bit = readBit()) !== null) {
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node = node[bit];
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if (typeof node === 'number')
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return node;
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if (typeof node !== 'object')
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throw "invalid huffman sequence";
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}
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return null;
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}
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function receive(length) {
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var n = 0;
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while (length > 0) {
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var bit = readBit();
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if (bit === null) return;
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n = (n << 1) | bit;
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length--;
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}
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return n;
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}
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function receiveAndExtend(length) {
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var n = receive(length);
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if (n >= 1 << (length - 1))
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return n;
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return n + (-1 << length) + 1;
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}
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function decodeBaseline(component) {
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var zz = new Int32Array(64);
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var t = decodeHuffman(component.huffmanTableDC);
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var diff = t === 0 ? 0 : receiveAndExtend(t);
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zz[0]= (component.pred += diff);
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var k = 1;
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while (k < 64) {
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var rs = decodeHuffman(component.huffmanTableAC);
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var s = rs & 15, r = rs >> 4;
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if (s === 0) {
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if (r != 15)
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break;
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k += 16;
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continue;
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}
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k += r;
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zz[k] = receiveAndExtend(s);
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k++;
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}
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return zz;
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}
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function quantizeAndInverse(zz, qt) {
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var R = new Int32Array([
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zz[0] * qt[0], zz[1] * qt[1], zz[5] * qt[5], zz[6] * qt[6], zz[14] * qt[14], zz[15] * qt[15], zz[27] * qt[27], zz[28] * qt[28],
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zz[2] * qt[2], zz[4] * qt[4], zz[7] * qt[7], zz[13] * qt[13], zz[16] * qt[16], zz[26] * qt[26], zz[29] * qt[29], zz[42] * qt[42],
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zz[3] * qt[3], zz[8] * qt[8], zz[12] * qt[12], zz[17] * qt[17], zz[25] * qt[25], zz[30] * qt[30], zz[41] * qt[41], zz[43] * qt[43],
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zz[9] * qt[9], zz[11] * qt[11], zz[18] * qt[18], zz[24] * qt[24], zz[31] * qt[31], zz[40] * qt[40], zz[44] * qt[44], zz[53] * qt[53],
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zz[10] * qt[10], zz[19] * qt[19], zz[23] * qt[23], zz[32] * qt[32], zz[39] * qt[39], zz[45] * qt[45], zz[52] * qt[52], zz[54] * qt[54],
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zz[20] * qt[20], zz[22] * qt[22], zz[33] * qt[33], zz[38] * qt[38], zz[46] * qt[46], zz[51] * qt[51], zz[55] * qt[55], zz[60] * qt[60],
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zz[21] * qt[21], zz[34] * qt[34], zz[37] * qt[37], zz[47] * qt[47], zz[50] * qt[50], zz[56] * qt[56], zz[59] * qt[59], zz[61] * qt[61],
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zz[35] * qt[35], zz[36] * qt[36], zz[48] * qt[48], zz[49] * qt[49], zz[57] * qt[57], zz[58] * qt[58], zz[62] * qt[62], zz[63] * qt[63]]);
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var i, j, y, x, u, v;
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var r = new Uint8Array(64), ri;
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for (i = 0; i < 64; i++) {
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var sum = 0;
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var table = iDCTTables[i];
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for (j = 0; j < 64; j++)
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sum += table[j] * R[j];
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// TODO loosing precision?
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var sample = 128 + ((sum / 4) >> (precision - 8));
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// clamping
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r[i] = sample < 0 ? 0 : sample > 0xFF ? 0xFF : sample;
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}
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return r;
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}
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function storeMcu(component, r, mcu, row, col) {
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var mcuRow = (mcu / component.mcusPerLine) | 0;
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var mcuCol = mcu % component.mcusPerLine;
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var blockRow = mcuRow * component.v + row;
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var blockCol = mcuCol * component.h + col;
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var scanLine = blockRow << 3, sample = blockCol << 3;
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var lines = component.lines;
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while (scanLine + 8 > lines.length) {
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lines.push(new Uint8Array(component.blocksPerLine << 3));
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}
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var i, j, offset = 0;
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for (j = 0; j < 8; j++) {
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var line = lines[scanLine + j];
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for (i = 0; i < 8; i++)
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line[sample + i] = r[offset++];
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}
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}
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function storeBlock(component, r, mcu) {
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var blockRow = (mcu / component.mcusPerLine) | 0;
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var blockCol = mcu % component.mcusPerLine;
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var scanLine = blockRow << 3, sample = blockCol << 3;
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var lines = component.lines;
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while (scanLine + 8 > lines.length) {
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lines.push(new Uint8Array(component.blocksPerLine << 3));
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}
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var i, j, offset = 0;
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for (j = 0; j < 8; j++) {
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var line = lines[scanLine + j];
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for (i = 0; i < 8; i++)
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line[sample + i] = r[offset++];
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}
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}
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var componentsLength = components.length;
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var component, i, j, k, n;
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if (progressive) {
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throw "not implemented: progressive";
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} else {
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for (i = 0; i < componentsLength; i++) {
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component = components[i];
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component.blocksPerLine = (samplesPerLine * component.h / maxH + 7) >> 3;
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component.mcusPerLine = ((component.blocksPerLine + component.h - 1) / component.h) | 0;
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component.decode = decodeBaseline;
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}
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}
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var mcu = 0, marker;
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var mcuExpected =
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(0|((((samplesPerLine + 7) >> 3) + maxH - 1) / maxH)) *
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(0|((((scanLines + 7) >> 3) + maxV - 1) / maxV));
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if (!resetInterval) resetInterval = mcuExpected;
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var zz, r;
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while (mcu < mcuExpected) {
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if (componentsLength == 1) {
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component = components[0];
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for (n = 0; n < resetInterval; n++) {
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zz = component.decode(component);
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r = quantizeAndInverse(zz, component.quantizationTable);
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storeBlock(component, r, mcu);
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mcu++;
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}
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} else {
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for (n = 0; n < resetInterval; n++) {
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for (i = 0; i < componentsLength; i++) {
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component = components[i];
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var h = component.h, v = component.v;
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for (j = 0; j < v; j++) {
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for (k = 0; k < h; k++) {
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zz = component.decode(component);
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r = quantizeAndInverse(zz, component.quantizationTable);
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storeMcu(component, r, mcu, j, k);
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}
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}
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}
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mcu++;
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}
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}
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// find marker
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bitsCount = 0;
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marker = (data[offset] << 8) | data[offset + 1];
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if (marker <= 0xFF00) {
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throw "marker was not found";
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}
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if (marker >= 0xFFD0 && marker <= 0xFFD7) { // RSTx
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offset += 2;
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for (i = 0; i < componentsLength; i++)
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components[i].pred = 0;
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}
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else
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break;
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}
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return offset - startOffset;
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}
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constructor.prototype = {
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load: function(path) {
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var xhr = new XMLHttpRequest();
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xhr.open("GET", path, true);
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xhr.responseType = "arraybuffer";
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xhr.onload = (function() {
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// TODO catch parse error
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var data = new Uint8Array(xhr.response || xhr.mozResponseArrayBuffer);
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this.parse(data);
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if (this.onload)
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this.onload();
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}).bind(this);
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xhr.send(null);
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},
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parse: function(data) {
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var offset = 0, length = data.length;
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function readUint16() {
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var value = (data[offset] << 8) | data[offset + 1];
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offset += 2;
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return value;
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}
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function readDataBlock() {
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var length = readUint16();
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//var array = data.subarray(offset, offset + length - 2);
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var array = data.slice(offset, offset + length - 2);
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offset += array.length;
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return array;
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}
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var jfif = null;
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var adobe = null;
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var pixels = null;
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var frame, resetInterval;
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var quantizationTables = [], frames = [];
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var huffmanTablesAC = [], huffmanTablesDC = [];
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var fileMarker = readUint16();
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if (fileMarker != 0xFFD8) { // SOI (Start of Image)
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throw "SOI not found";
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}
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fileMarker = readUint16();
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while (fileMarker != 0xFFD9) { // EOI (End of image)
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var i, j, l;
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switch(fileMarker) {
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case 0xFFE0: // APP0 (Application Specific)
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case 0xFFE1: // APP1
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case 0xFFE2: // APP2
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case 0xFFE3: // APP3
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case 0xFFE4: // APP4
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case 0xFFE5: // APP5
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case 0xFFE6: // APP6
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case 0xFFE7: // APP7
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case 0xFFE8: // APP8
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case 0xFFE9: // APP9
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case 0xFFEA: // APP10
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case 0xFFEB: // APP11
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case 0xFFEC: // APP12
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case 0xFFED: // APP13
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case 0xFFEE: // APP14
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case 0xFFEF: // APP15
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case 0xFFFE: // COM (Comment)
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var appData = readDataBlock();
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if (fileMarker === 0xFFE0) {
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if (appData[0] === 0x4A && appData[1] === 0x46 && appData[2] === 0x49 &&
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appData[3] === 0x46 && appData[4] === 0) { // 'JFIF\x00'
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jfif = {
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version: { major: appData[5], minor: appData[6] },
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densityUnits: appData[7],
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xDensity: (appData[8] << 8) | appData[9],
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yDensity: (appData[10] << 8) | appData[11],
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thumbWidth: appData[12],
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thumbHeight: appData[13],
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//thumbData: appData.subarray(14, 14 + 3 * appData[12] * appData[13])
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thumbData: appData.slice(14, 14 + 3 * appData[12] * appData[13])
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};
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}
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}
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// TODO APP1 - Exif
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if (fileMarker === 0xFFEE) {
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if (appData[0] === 0x41 && appData[1] === 0x64 && appData[2] === 0x6F &&
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appData[3] === 0x62 && appData[4] === 65 && appData[5] === 0) { // 'Adobe\x00'
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adobe = {
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version: appData[6],
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flags0: (appData[7] << 8) | appData[8],
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flags1: (appData[9] << 8) | appData[10],
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transformCode: appData[11]
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};
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}
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}
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break;
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case 0xFFDB: // DQT (Define Quantization Tables)
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var quantizationTableCount = Math.floor((readUint16() - 2) / 65);
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for (i = 0; i < quantizationTableCount; i++) {
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var quantizationTableSpec = data[offset++];
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var tableData = new Int32Array(64);
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if ((quantizationTableSpec >> 4) === 0) { // 8 bit values
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for (j = 0; j < 64; j++)
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tableData[j] = data[offset++];
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} else if ((quantizationTableSpec >> 4) === 1) { //16 bit
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tableData[j] = readUint16();
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} else
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throw "DQT: invalid table spec";
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quantizationTables[quantizationTableSpec & 15] = tableData;
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}
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break;
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case 0xFFC0: // SOF0 (Start of Frame, Baseline DCT)
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case 0xFFC2: // SOF2 (Start of Frame, Progressive DCT)
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readUint16(); // skip data length
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frame = {};
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frame.progressive = (fileMarker === 0xFFC2);
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frame.precision = data[offset++];
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frame.scanLines = readUint16();
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frame.samplesPerLine = readUint16();
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frame.components = [];
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var componentsCount = data[offset++];
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var maxH = 0, maxV = 0;
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for (i = 0; i < componentsCount; i++) {
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var componentId = data[offset];
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var h = data[offset + 1] >> 4;
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var v = data[offset + 1] & 15;
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var qId = data[offset + 2];
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frame.components[componentId] = {
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h: h,
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v: v,
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quantizationTable: quantizationTables[qId],
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pred: 0,
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lines: []
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};
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offset += 3;
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if (maxH < h) maxH = h;
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if (maxV < v) maxV = v;
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}
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frame.maxH = maxH;
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frame.maxV = maxV;
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frames.push(frame);
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break;
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case 0xFFC4: // DHT (Define Huffman Tables)
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var huffmanLength = readUint16();
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for (i = 2; i < huffmanLength;) {
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var huffmanTableSpec = data[offset++];
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var codeLengths = new Uint8Array(16);
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var codeLengthSum = 0;
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for (j = 0; j < 16; j++, offset++)
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codeLengthSum += (codeLengths[j] = data[offset]);
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var huffmanValues = new Uint8Array(codeLengthSum);
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for (j = 0; j < codeLengthSum; j++, offset++)
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huffmanValues[j] = data[offset];
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i += 17 + codeLengthSum;
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((huffmanTableSpec >> 4) === 0 ?
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huffmanTablesDC : huffmanTablesAC)[huffmanTableSpec & 15] =
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buildHuffmanTable(codeLengths, huffmanValues);
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}
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break;
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case 0xFFDD: // DRI (Define Restart Interval)
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readUint16(); // skip data length
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resetInterval = readUint16();
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break;
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case 0xFFDA: // SOS (Start of Scan)
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var scanLength = readUint16();
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var selectorsCount = data[offset++];
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var components = [], component;
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for (i = 0; i < selectorsCount; i++) {
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component = frame.components[data[offset++]];
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var tableSpec = data[offset++];
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component.huffmanTableDC = huffmanTablesDC[tableSpec >> 4];
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component.huffmanTableAC = huffmanTablesAC[tableSpec & 15];
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components.push(component);
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}
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var spectralStart = data[offset++];
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var spectralEnd = data[offset++];
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var successiveApproximation = data[offset++];
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var processed = decodeScan(data, offset,
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frame, components, resetInterval,
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spectralStart, spectralEnd,
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|
successiveApproximation >> 4, successiveApproximation & 15);
|
|
offset += processed;
|
|
break;
|
|
default:
|
|
throw "unknown JPEG marker " + fileMarker.toString(16);
|
|
}
|
|
fileMarker = readUint16();
|
|
}
|
|
if (frames.length != 1)
|
|
throw "only single frame JPEGs supported";
|
|
|
|
this.width = frame.samplesPerLine;
|
|
this.height = frame.scanLines;
|
|
this.jfif = jfif;
|
|
this.adobe = adobe;
|
|
this.components = [];
|
|
for (var id in frame.components) {
|
|
if (frame.components.hasOwnProperty(id)) {
|
|
this.components.push({
|
|
lines: frame.components[id].lines,
|
|
scaleX: frame.components[id].h / frame.maxH,
|
|
scaleY: frame.components[id].v / frame.maxV
|
|
});
|
|
}
|
|
}
|
|
},
|
|
copyToImageData: function(imageData) {
|
|
var width = imageData.width, height = imageData.height;
|
|
var scaleX = this.width / width, scaleY = this.height / height;
|
|
|
|
var component1, component2, component3, component4;
|
|
var component1Line, component2Line, component3Line, component4Line;
|
|
var x, y;
|
|
var offset = 0, data = imageData.data;
|
|
var Y, Cb, Cr, K, C, M, Ye;
|
|
switch (this.components.length) {
|
|
case 1:
|
|
component1 = this.components[0];
|
|
for (y = 0; y < height; y++) {
|
|
component1Line = component1.lines[0 | (y * component1.scaleY * scaleY)];
|
|
for (x = 0; x < width; x++) {
|
|
Y = component1Line[0 | (x * component1.scaleX * scaleX)];
|
|
|
|
data[offset++] = Y;
|
|
data[offset++] = Y;
|
|
data[offset++] = Y;
|
|
data[offset++] = 255;
|
|
}
|
|
}
|
|
break;
|
|
case 3:
|
|
component1 = this.components[0];
|
|
component2 = this.components[1];
|
|
component3 = this.components[2];
|
|
for (y = 0; y < height; y++) {
|
|
component1Line = component1.lines[0 | (y * component1.scaleY * scaleY)];
|
|
component2Line = component2.lines[0 | (y * component2.scaleY * scaleY)];
|
|
component3Line = component3.lines[0 | (y * component3.scaleY * scaleY)];
|
|
for (x = 0; x < width; x++) {
|
|
Y = component1Line[0 | (x * component1.scaleX * scaleX)];
|
|
Cb = component2Line[0 | (x * component2.scaleX * scaleX)];
|
|
Cr = component3Line[0 | (x * component3.scaleX * scaleX)];
|
|
|
|
data[offset++] = Y + 1.402 * (Cr - 128);
|
|
data[offset++] = Y - 0.3441363 * (Cb - 128) - 0.71413636 * (Cr - 128);
|
|
data[offset++] = Y + 1.772 * (Cb - 128);
|
|
data[offset++] = 255;
|
|
}
|
|
}
|
|
break;
|
|
case 4:
|
|
component1 = this.components[0];
|
|
component2 = this.components[1];
|
|
component3 = this.components[2];
|
|
component4 = this.components[3];
|
|
for (y = 0; y < height; y++) {
|
|
component1Line = component1.lines[0 | (y * component1.scaleY * scaleY)];
|
|
component2Line = component2.lines[0 | (y * component2.scaleY * scaleY)];
|
|
component3Line = component3.lines[0 | (y * component3.scaleY * scaleY)];
|
|
component4Line = component4.lines[0 | (y * component4.scaleY * scaleY)];
|
|
for (x = 0; x < width; x++) {
|
|
Y = component1Line[0 | (x * component1.scaleX * scaleX)];
|
|
Cb = component2Line[0 | (x * component2.scaleX * scaleX)];
|
|
Cr = component3Line[0 | (x * component3.scaleX * scaleX)];
|
|
K = component4Line[0 | (x * component4.scaleX * scaleX)];
|
|
|
|
C = 255 - (Y + 1.402 * (Cr - 128));
|
|
M = 255 - (Y - 0.3441363 * (Cb - 128) - 0.71413636 * (Cr - 128));
|
|
Ye = 255 - (Y + 1.772 * (Cb - 128));
|
|
|
|
data[offset++] = 255 - Math.min(255, C * (1 - K / 255) + K);
|
|
data[offset++] = 255 - Math.min(255, M * (1 - K / 255) + K);
|
|
data[offset++] = 255 - Math.min(255, Ye * (1 - K / 255) + K);
|
|
data[offset++] = 255;
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
};
|
|
|
|
return constructor;
|
|
})();
|
|
|
|
var Buffer = require('buffer').Buffer;
|
|
var fs = require('fs');
|
|
|
|
module.exports.readJpeg = function(path)
|
|
{
|
|
var jpgData = fs.readFileSync(path);
|
|
var j = new JpegImage();
|
|
j.parse(jpgData);
|
|
var imageData = {};
|
|
imageData.width = j.width;
|
|
imageData.height = j.height;
|
|
imageData.data = new Buffer(j.width*j.height*4);
|
|
j.copyToImageData(imageData);
|
|
return imageData;
|
|
}
|