bv7_jpeg_encoder

array -> jpeg

Version au 14/03/2018. Voir la dernière version.

Ce script ne doit pas être installé directement. C'est une librairie destinée à être incluse dans d'autres scripts avec la méta-directive // @require https://update.greatest.deepsurf.us/scripts/39476/258527/bv7_jpeg_encoder.js

Vous devrez installer une extension telle que Tampermonkey, Greasemonkey ou Violentmonkey pour installer ce script.

Vous devrez installer une extension telle que Tampermonkey ou Violentmonkey pour installer ce script.

Vous devrez installer une extension telle que Tampermonkey ou Violentmonkey pour installer ce script.

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// ==UserScript==
// @name         bv7_jpeg_encoder
// @namespace    bv7
// @version      0.1
// @description  array -> jpeg
// @author       bv7
// ==/UserScript==

class JpegEncoder {
	constructor() {
		this.zigZag = [
			0x00, 0x01, 0x05, 0x06, 0x0E, 0x0F, 0x1B, 0x1C,
			0x02, 0x04, 0x07, 0x0D, 0x10, 0x1A, 0x1D, 0x2A,
			0x03, 0x08, 0x0C, 0x11, 0x19, 0x1E, 0x29, 0x2B,
			0x09, 0x0B, 0x12, 0x18, 0x1F, 0x28, 0x2C, 0x35,
			0x0A, 0x13, 0x17, 0x20, 0x27, 0x2D, 0x34, 0x36,
			0x14, 0x16, 0x21, 0x26, 0x2E, 0x33, 0x37, 0x3C,
			0x15, 0x22, 0x25, 0x2F, 0x32, 0x38, 0x3B, 0x3D,
			0x23, 0x24, 0x30, 0x31, 0x39, 0x3A, 0x3E, 0x3F
		];
		this.std_dc_luminance_nrcodes = [
			0x00, 0x01, 0x05, 0x01, 0x01, 0x01, 0x01, 0x01,
			0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
		];
		this.std_dc_luminance_values  = [
			0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
			0x08, 0x09, 0x0A, 0x0B
		];
		this.std_ac_luminance_nrcodes = [
			0x00, 0x02, 0x01, 0x03, 0x03, 0x02, 0x04, 0x03,
			0x05, 0x05, 0x04, 0x04, 0x00, 0x00, 0x01, 0x7D
		];
		this.std_ac_luminance_values  = [
			0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12,
			0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,
			0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xA1, 0x08,
			0x23, 0x42, 0xB1, 0xC1, 0x15, 0x52, 0xD1, 0xF0,
			0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0A, 0x16,
			0x17, 0x18, 0x19, 0x1A, 0x25, 0x26, 0x27, 0x28,
			0x29, 0x2A, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
			0x3A, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
			0x4A, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
			0x5A, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
			0x6A, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
			0x7A, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
			0x8A, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,
			0x99, 0x9A, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7,
			0xA8, 0xA9, 0xAA, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6,
			0xB7, 0xB8, 0xB9, 0xBA, 0xC2, 0xC3, 0xC4, 0xC5,
			0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xD2, 0xD3, 0xD4,
			0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xE1, 0xE2,
			0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA,
			0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8,
			0xF9, 0xFA
		];
		this.std_dc_chrominance_nrcodes = [
			0x00, 0x03, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
			0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00
		];
		this.std_dc_chrominance_values = [
			0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
			0x08, 0x09, 0x0A, 0x0B
		];
		this.std_ac_chrominance_nrcodes = [
			0x00, 0x02, 0x01, 0x02, 0x04, 0x04, 0x03, 0x04,
			0x07, 0x05, 0x04, 0x04, 0x00, 0x01, 0x02, 0x77
		];
		this.std_ac_chrominance_values = [
			0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21,
			0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71,
			0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91,
			0xA1, 0xB1, 0xC1, 0x09, 0x23, 0x33, 0x52, 0xF0,
			0x15, 0x62, 0x72, 0xD1, 0x0A, 0x16, 0x24, 0x34,
			0xE1, 0x25, 0xF1, 0x17, 0x18, 0x19, 0x1A, 0x26,
			0x27, 0x28, 0x29, 0x2A, 0x35, 0x36, 0x37, 0x38,
			0x39, 0x3A, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
			0x49, 0x4A, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
			0x59, 0x5A, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
			0x69, 0x6A, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
			0x79, 0x7A, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
			0x88, 0x89, 0x8A, 0x92, 0x93, 0x94, 0x95, 0x96,
			0x97, 0x98, 0x99, 0x9A, 0xA2, 0xA3, 0xA4, 0xA5,
			0xA6, 0xA7, 0xA8, 0xA9, 0xAA, 0xB2, 0xB3, 0xB4,
			0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xC2, 0xC3,
			0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xD2,
			0xD3, 0xD4, 0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA,
			0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9,
			0xEA, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8,
			0xF9, 0xFA
		];
		this.YDC_HT          = new Uint8Array(0x0B);
		this.UVDC_HT         = new Uint8Array(0x0B);
		this.YAC_HT          = new  Int8Array(0xFA);
		this.UVAC_HT         = new  Int8Array(0xFA);
		this.YDC_HT2         = new Uint8Array(0x0B);
		this.UVDC_HT2        = new Uint8Array(0x0B);
		this.YAC_HT2         = new Uint8Array(0xFA);
		this.UVAC_HT2        = new Uint8Array(0xFA);
		this.YTable          = new  Uint8Array(0x40  );
		this.UVTable         = new  Uint8Array(0x40  );
		this.fdtbl_Y         = [];
		this.fdtbl_UV        = new Float32Array(0x08);
		this.outputfDCTQuant = new Uint16Array(0x40  );
		this.DU              = new  Int16Array(0x40  );
		this.category        = new  Uint8Array(0xFFFE);
		this.bitcode         = new Uint16Array(0xFFFE);
		this.RGB_YUV_TABLE   = new Uint32Array(0x0800);
		this.YDU             = new  Int16Array(0x40  );
		this.UDU             = new  Int16Array(0x40  );
		this.VDU             = new  Int16Array(0x40  );
		this.initHuffmanTbl();
		this.initCategoryNumber();
		this.initRGBYUVTable();
	}
	// IO functions
	writeBits(value, posval) {
		while (posval >= 0) {
			if (value & (1 << posval)) this.bytenew |= (1 << this.bytepos);
			posval--;
			this.bytepos--;
			if (this.bytepos < 0) {
				this.writeByte(this.bytenew);
				if (this.bytenew == 0xFF) this.writeByte(0x00);
				this.bytepos = 7;
				this.bytenew = 0;
			}
		}
	}
	writeByte(value) {
		this.byteout.push(String.fromCharCode(value)); // write char directly instead of converting later
	}
	writeWord(value) {
		this.writeByte((value >> 8) & 0xFF);
        this.writeByte((value     ) & 0xFF);
    }
    writeAPP0() {
    	this.writeWord(0xFFE0); // marker
    	this.writeWord(0x0010); // length
    	this.writeByte(0x4A  ); // J
    	this.writeByte(0x46  ); // F
    	this.writeByte(0x49  ); // I
    	this.writeByte(0x46  ); // F
    	this.writeByte(0x00  ); // = "JFIF",'\0'
    	this.writeByte(0x01  ); // versionhi
    	this.writeByte(0x01  ); // versionlo
    	this.writeByte(0x00  ); // xyunits
    	this.writeWord(0x0001); // xdensity
    	this.writeWord(0x0001); // ydensity
    	this.writeByte(0x00  ); // thumbnwidth
    	this.writeByte(0x00  ); // thumbnheight
    }
	writeDQT() {
		this.writeWord(0xFFDB); // marker
		this.writeWord(0x0084); // length
		this.writeByte(0x00  );
		this.YTable.forEach((v) => this.writeByte(v));
        this.writeByte(0x01  );
        this.UVTable.forEach((v) => this.writeByte(v));
    }
	writeSOF0(width, height) {
		this.writeWord(0xFFC0); // marker
		this.writeWord(0x0011); // length, truecolor YUV JPG
		this.writeByte(0x08  ); // precision
		this.writeWord(height);
		this.writeWord(width );
		this.writeByte(0x03  ); // nrofcomponents
		this.writeByte(0x01  ); // IdY
		this.writeByte(0x11  ); // HVY
		this.writeByte(0x00  ); // QTY
		this.writeByte(0x02  ); // IdU
		this.writeByte(0x11  ); // HVU
		this.writeByte(0x01  ); // QTU
		this.writeByte(0x03  ); // IdV
		this.writeByte(0x11  ); // HVV
		this.writeByte(0x01  ); // QTV
	}
	writeDHT() {
		this.writeWord(0xFFC4); // marker
		this.writeWord(0x01A2); // length
		this.writeByte(0x00  ); // HTYDCinfo
		this.std_dc_luminance_nrcodes.forEach((v) => this.writeByte(v));
		this.std_dc_luminance_values.forEach((v) => this.writeByte(v));
		this.writeByte(0x10  ); // HTYACinfo
		this.std_ac_luminance_nrcodes.forEach((v) => this.writeByte(v));
		this.std_ac_luminance_values.forEach((v) => this.writeByte(v));
		this.writeByte(0x01  ); // HTUDCinfo
		this.std_dc_chrominance_nrcodes.forEach((v) => this.writeByte(v));
		this.std_dc_chrominance_values.forEach((v) => this.writeByte(v));
		this.writeByte(0x11  ); // HTUACinfo
		this.std_ac_chrominance_nrcodes.forEach((v) => this.writeByte(v));
		this.std_ac_chrominance_values.forEach((v) => this.writeByte(v));
	}
	writeSOS() {
		this.writeWord(0xFFDA); // marker
		this.writeWord(0x000C); // length
		this.writeByte(0x03  ); // nrofcomponents
		this.writeByte(0x01  ); // IdY
		this.writeByte(0x00  ); // HTY
		this.writeByte(0x02  ); // IdU
		this.writeByte(0x11  ); // HTU
		this.writeByte(0x03  ); // IdV
		this.writeByte(0x11  ); // HTV
		this.writeByte(0x00  ); // Ss
		this.writeByte(0x3F  ); // Se
		this.writeByte(0x00  ); // Bf
	}
	computeHuffmanTbl(nrcodes, std_table, HT, HT2) {
		let a, j;
		let codevalue    = 0;
		let pos_in_table = 0;
		nrcodes.forEach((nrcodesK, k) => {
			for (j = 0; j < nrcodesK; j++) {
				HT[a = std_table[pos_in_table++]] = codevalue++;
				HT2[a                           ] = k;
			}
			codevalue *= 2;
		});
	}
	initHuffmanTbl() {
		this.computeHuffmanTbl(this.std_dc_luminance_nrcodes  , this.std_dc_luminance_values  , this.YDC_HT , this.YDC_HT2 );
		this.computeHuffmanTbl(this.std_dc_chrominance_nrcodes, this.std_dc_chrominance_values, this.UVDC_HT, this.UVDC_HT2);
		this.computeHuffmanTbl(this.std_ac_luminance_nrcodes  , this.std_ac_luminance_values  , this.YAC_HT , this.YAC_HT2 );
		this.computeHuffmanTbl(this.std_ac_chrominance_nrcodes, this.std_ac_chrominance_values, this.UVAC_HT, this.UVAC_HT2);
	}
	initCategoryNumber() {
		let cat, nr, nrlower, nrupper, nrn;
		for (cat = 0, nrlower = 1, nrupper = 2; cat < 15; cat++, nrlower = nrupper, nrupper <<= 1) {
			for (nr = nrlower, nrn = nrlower - 1; nr < nrupper; nr++, nrn--) { //Positive & Negative numbers
				this.category[0x7FFF + nr] = this.category[0x7FFF - nr] = cat;
				this.bitcode[ 0x7FFF + nr] = nr;
				this.bitcode[ 0x7FFF - nr] = nrn;
			}
		}
	}
	initRGBYUVTable() {
		for(let i = 0x0000; i < 0x0100; i++) {
			this.RGB_YUV_TABLE[i         ] =   0x004C8B * i           ;
			this.RGB_YUV_TABLE[i + 0x0100] =   0x009646 * i           ;
			this.RGB_YUV_TABLE[i + 0x0200] =   0x001D2F * i + 0x008000;
			this.RGB_YUV_TABLE[i + 0x0300] = - 0x002B33 * i           ;
			this.RGB_YUV_TABLE[i + 0x0400] = - 0x0054CD * i           ;
			this.RGB_YUV_TABLE[i + 0x0500] =   0x008000 * i + 0x807FFF;
			this.RGB_YUV_TABLE[i + 0x0600] = - 0x006B2F * i           ;
			this.RGB_YUV_TABLE[i + 0x0700] = - 0x0014D1 * i           ;
		}
	}
	initQuantTables(sf) {
		let i, t;
		let row;
		let col;
		[
			0x10, 0x0B, 0x0A, 0x10, 0x18, 0x28, 0x33, 0x3D,
			0x0C, 0x0C, 0x0E, 0x13, 0x1A, 0x3A, 0x3C, 0x37,
			0x0E, 0x0D, 0x10, 0x18, 0x28, 0x39, 0x45, 0x38,
			0x0E, 0x11, 0x16, 0x1D, 0x33, 0x57, 0x50, 0x3E,
			0x12, 0x16, 0x25, 0x38, 0x44, 0x6D, 0x67, 0x4D,
			0x18, 0x23, 0x37, 0x40, 0x51, 0x68, 0x71, 0x5C,
			0x31, 0x40, 0x4E, 0x57, 0x67, 0x79, 0x78, 0x65,
			0x48, 0x5C, 0x5F, 0x62, 0x70, 0x64, 0x67, 0x63
		].forEach((v, i) => this.YTable[this.zigZag[i]] = (t = 0 | ((v * sf + 50) / 100)) < 1 ? 1 : t > 0xFF ? 0xFF : t);
		[
			0x11, 0x12, 0x18, 0x2F, 0x63, 0x63, 0x63, 0x63,
			0x12, 0x15, 0x1A, 0x42, 0x63, 0x63, 0x63, 0x63,
			0x18, 0x1A, 0x38, 0x63, 0x63, 0x63, 0x63, 0x63,
			0x2F, 0x42, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63,
			0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63,
			0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63,
			0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63,
			0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63
		].forEach((v, i) => this.UVTable[this.zigZag[i]] = (t = 0 | ((v * sf + 50) / 100)) < 1 ? 1 : t > 0xFF ? 0xFF : t);
		let aasf = [
			1.0, 1.387039845, 1.306562965, 1.175875602,
			1.0, 0.785694958, 0.541196100, 0.275899379
		];
		for (i = 0, row = 0; row < 8; row++) for (col = 0; col < 8; col++, i++) {
			this.fdtbl_Y[i]  = 1.0 / (this.YTable [this.zigZag[i]] * aasf[row] * aasf[col] * 8.0);
			this.fdtbl_UV[i] = 1.0 / (this.UVTable[this.zigZag[i]] * aasf[row] * aasf[col] * 8.0);
		}
    }
	fDCTQuant(data, fdtbl) { // DCT & quantization core
		let d0, d1, d2, d3, d4, d5, d6, d7;
		let t0, t1, t2, t3, t4, t5, t6, t7;
		// Pass 1: process rows.
		let i, p;
		for (i = p = 0; i < 8; ++i, p += 8) { // advance pointer to next row
			d0 = data[p    ];
			d1 = data[p + 1];
			d2 = data[p + 2];
			d3 = data[p + 3];
			d4 = data[p + 4];
			d5 = data[p + 5];
			d6 = data[p + 6];
			d7 = data[p + 7];
			t0 = d0 + d7;
			t7 = d0 - d7;
			t1 = d1 + d6;
			t6 = d1 - d6;
			t2 = d2 + d5;
			t5 = d2 - d5;
			t3 = d3 + d4;
			t4 = d3 - d4;
			// Even part
			d0          = t0 + t3;    // phase 2
			d1          = t1 + t2;
			d2          = t1 - t2;
			d3          = t0 - t3;
			data[p    ] = d0 + d1;    // phase 3
			data[p + 4] = d0 - d1;
			d0          = (d2 + d3) * 0.707106781; // c4
			data[p + 2] = d3 + d0;    // phase 5
			data[p + 6] = d3 - d0;
			// Odd part
			d0 = t4 + t5;             // phase 2
			d1 = t5 + t6;
			d2 = t6 + t7;
			// The rotator is modified from fig 4-8 to avoid extra negations.
			d3          = 0.382683433 * (d0 - d2); // c6
			t2          = 0.541196100 * d0 + d3;   // c2-c6
			t4          = 1.306562965 * d2 + d3;   // c2+c6
			t3          = 0.707106781 * d1     ;   // c4
			d1          = t7 + t3;    // phase 5
			d3          = t7 - t3;
			data[p + 1] = d1 + t4;    // phase 6
			data[p + 3] = d3 - t2;
			data[p + 5] = d3 + t2;
			data[p + 7] = d1 - t4;
		}
		// Pass 2: process columns.
		for (i = p = 0; i < 8; ++i, p++) { // advance pointer to next column
			d0 = data[p       ];
			d1 = data[p + 0x08];
			d2 = data[p + 0x10];
			d3 = data[p + 0x18];
			d4 = data[p + 0x20];
			d5 = data[p + 0x28];
			d6 = data[p + 0x30];
			d7 = data[p + 0x38];
			t0 = d0 + d7;
			t1 = d1 + d6;
			t2 = d2 + d5;
			t3 = d3 + d4;
			t4 = d3 - d4;
			t5 = d2 - d5;
			t6 = d1 - d6;
			t7 = d0 - d7;
			// Even part
			d0             = t0 + t3; // phase 2
			d1             = t1 + t2;
			d2             = t1 - t2;
			d3             = t0 - t3;
			data[p       ] = d0 + d1; // phase 3
			data[p + 0x20] = d0 - d1;
			d0             = (d2 + d3) * 0.707106781; // c4
			data[p + 0x10] = d3 + d0; // phase 5
			data[p + 0x30] = d3 - d0;
			// Odd part
			d0 = t4 + t5;             // phase 2
			d1 = t5 + t6;
			d2 = t6 + t7;
			// The rotator is modified from fig 4-8 to avoid extra negations.
			d3             = 0.382683433 * (d0 - d2); // c6
			t2             = 0.541196100 * d0 + d3;   // c2-c6
			t4             = 1.306562965 * d2 + d3;   // c2+c6
			t3             = 0.707106781 * d1;        // c4
			d1             = t7 + t3; // phase 5
			d3             = t7 - t3;
			data[p + 0x08] = d1 + t4; // phase 6
			data[p + 0x18] = d3 - t2;
			data[p + 0x28] = d3 + t2;
			data[p + 0x38] = d1 - t4;
		}
		// Quantize/descale the coefficients
		// Apply the quantization and scaling factor & Round to nearest integer
		for (i = 0; i < 64; ++i) this.outputfDCTQuant[i] = ((d0 = data[i] * fdtbl[i]) > 0.0) ? ((d0 + 0.5)|0) : ((d0 - 0.5)|0); //outputfDCTQuant[i] = fround(d0);
		return this.outputfDCTQuant;
	}
	processDU(CDU, fdtbl, DC, HTDC, HTAC, HTDC2, HTAC2) {
		let pos, i, a;
		let EOB        = HTAC[0x00];
		let EOB2       = HTAC2[0x00];
		let M16zeroes  = HTAC[0xF0];
		let M16zeroes2 = HTAC2[0xF0];
		let DU_DCT     = this.fDCTQuant(CDU, fdtbl);
		//ZigZag reorder
		for (i = 0; i < 64; ++i) this.DU[this.zigZag[i]] = DU_DCT[i];
		let Diff = this.DU[0] - DC;
		DC = this.DU[0];
		//Encode DC
		if (Diff == 0) this.writeBits(HTDC[0], HTDC2[0]); // Diff might be 0
		else {
			pos = 0x7FFF + Diff;
			this.writeBits(HTDC[a = this.category[pos] + 1], HTDC2[a]);
			this.writeBits(this.bitcode[pos], this.category[pos]);
		}
		//Encode ACs
		let end0pos = 0x3F; // was const... which is crazy
		while (end0pos > 0 && this.DU[end0pos] == 0) end0pos--;
		if (end0pos == 0) this.writeBits(EOB, EOB2); //end0pos = first element in reverse order !=0
		else {
			let lng, startpos, nrzeroes, nrmarker;
			end0pos++;
			for (i = 1; i < end0pos; i++) {
				startpos = i;
				while (this.DU[i] == 0 && i < end0pos) ++i;
				nrzeroes = i - startpos;
				if (nrzeroes > 0x0F) {
					lng = nrzeroes >> 4;
					for (nrmarker = 0; nrmarker < lng; ++nrmarker) this.writeBits(M16zeroes, M16zeroes2);
					nrzeroes = nrzeroes & 0x0F;
				}
				this.writeBits(HTAC[a = (nrzeroes << 4) + this.category[pos = 0x7FFF + this.DU[i]] + 1], HTAC2[a]);
				this.writeBits(this.bitcode[pos], this.category[pos]);
			}
			if (end0pos != 0x40) this.writeBits(EOB, EOB2);
		}
		return DC;
	}
	encode(imageData, quality = 0.92) { // image data object
		this.byteout = []; // Initialize bit writer
		this.bytenew = 0;
		this.bytepos = 7;
		let newSf = Math.floor(quality < 0.5 ? 50 / quality : 200 * (1 - quality));
		if ((typeof this.sf) == 'undefined' || newSf !== this.sf) this.initQuantTables(this.sf = newSf);
		// Add JPEG headers
		this.writeWord(0xFFD8); // SOI
		this.writeAPP0();
		this.writeDQT();
		this.writeSOF0(imageData.width, imageData.height);
		this.writeDHT();
		this.writeSOS();
		let y1, y2, y3, pY3, pY1;
		let x1, x2, x3, pX3, pX1;
		let r, g, b;
		let pos;
		let quadWidth = imageData.width *  4;
		let width32   = imageData.width * 32;
		// Encode 8x8 macroblocks
		let DCY = 0;
		let DCU = 0;
		let DCV = 0;
		for (y1 = 0, pY1 = 0; y1 < imageData.height; y1 += 8, pY1 += width32) {
			for (x1 = 0, pX1 = pY1; x1 < imageData.width; x1 += 8, pX1 += 32) {
				for (y2 = pos = 0, y3 = y1, pY3 = pX1; y2 < 8; y2++, y3++, pY3 += quadWidth) {
					for (x2 = 0, x3 = x1, pX3 = pY3; x2 < 8; x2++, x3++, pos++) {
						if (y3 < imageData.height && x3 < imageData.width) {
							r = imageData.data[pX3++];
							g = imageData.data[pX3++];
							b = imageData.data[pX3++];
							pX3++;
						} else r = g = b = 0; // padding
						this.YDU[pos] = ((this.RGB_YUV_TABLE[r         ] + this.RGB_YUV_TABLE[g + 0x0100] + this.RGB_YUV_TABLE[b + 0x0200]) >> 16) - 0x80;
						this.UDU[pos] = ((this.RGB_YUV_TABLE[r + 0x0300] + this.RGB_YUV_TABLE[g + 0x0400] + this.RGB_YUV_TABLE[b + 0x0500]) >> 16) - 0x80;
						this.VDU[pos] = ((this.RGB_YUV_TABLE[r + 0x0500] + this.RGB_YUV_TABLE[g + 0x0600] + this.RGB_YUV_TABLE[b + 0x0700]) >> 16) - 0x80;
					}
				}
				DCY = this.processDU(this.YDU, this.fdtbl_Y , DCY,  this.YDC_HT,  this.YAC_HT,  this.YDC_HT2,  this.YAC_HT2);
				DCU = this.processDU(this.UDU, this.fdtbl_UV, DCU, this.UVDC_HT, this.UVAC_HT, this.UVDC_HT2, this.UVAC_HT2);
				DCV = this.processDU(this.VDU, this.fdtbl_UV, DCV, this.UVDC_HT, this.UVAC_HT, this.UVDC_HT2, this.UVAC_HT2);
			}
		}
		////////////////////////////////////////////////////////////////
		// Do the bit alignment of the EOI marker
		if (this.bytepos >= 0) this.writeBits((1 << (this.bytepos + 1)) - 1, this.bytepos);
		this.writeWord(0xFFD9); //EOI
		let res = 'data:image/jpeg;base64,' + btoa(this.byteout.join(''));
		this.byteout = [];
		return res;
	}
}