xswitch/clients/flex/com/adobe/images/JPGEncoder.as

/*
  Copyright (c) 2008, Adobe Systems Incorporated
  All rights reserved.

  Redistribution and use in source and binary forms, with or without 
  modification, are permitted provided that the following conditions are
  met:

  * Redistributions of source code must retain the above copyright notice, 
    this list of conditions and the following disclaimer.
  
  * Redistributions in binary form must reproduce the above copyright
    notice, this list of conditions and the following disclaimer in the 
    documentation and/or other materials provided with the distribution.
  
  * Neither the name of Adobe Systems Incorporated nor the names of its 
    contributors may be used to endorse or promote products derived from 
    this software without specific prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
  IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR 
  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package com.adobe.images
{
	import flash.geom.*;
	import flash.display.*;
	import flash.utils.*;
	
	/**
	 * Class that converts BitmapData into a valid JPEG
	 */		
	public class JPGEncoder
	{

		// Static table initialization
	
		private var ZigZag:Array = [
			 0, 1, 5, 6,14,15,27,28,
			 2, 4, 7,13,16,26,29,42,
			 3, 8,12,17,25,30,41,43,
			 9,11,18,24,31,40,44,53,
			10,19,23,32,39,45,52,54,
			20,22,33,38,46,51,55,60,
			21,34,37,47,50,56,59,61,
			35,36,48,49,57,58,62,63
		];
	
		private var YTable:Array = new Array(64);
		private var UVTable:Array = new Array(64);
		private var fdtbl_Y:Array = new Array(64);
		private var fdtbl_UV:Array = new Array(64);
	
		private function initQuantTables(sf:int):void
		{
			var i:int;
			var t:Number;
			var YQT:Array = [
				16, 11, 10, 16, 24, 40, 51, 61,
				12, 12, 14, 19, 26, 58, 60, 55,
				14, 13, 16, 24, 40, 57, 69, 56,
				14, 17, 22, 29, 51, 87, 80, 62,
				18, 22, 37, 56, 68,109,103, 77,
				24, 35, 55, 64, 81,104,113, 92,
				49, 64, 78, 87,103,121,120,101,
				72, 92, 95, 98,112,100,103, 99
			];
			for (i = 0; i < 64; i++) {
				t = Math.floor((YQT[i]*sf+50)/100);
				if (t < 1) {
					t = 1;
				} else if (t > 255) {
					t = 255;
				}
				YTable[ZigZag[i]] = t;
			}
			var UVQT:Array = [
				17, 18, 24, 47, 99, 99, 99, 99,
				18, 21, 26, 66, 99, 99, 99, 99,
				24, 26, 56, 99, 99, 99, 99, 99,
				47, 66, 99, 99, 99, 99, 99, 99,
				99, 99, 99, 99, 99, 99, 99, 99,
				99, 99, 99, 99, 99, 99, 99, 99,
				99, 99, 99, 99, 99, 99, 99, 99,
				99, 99, 99, 99, 99, 99, 99, 99
			];
			for (i = 0; i < 64; i++) {
				t = Math.floor((UVQT[i]*sf+50)/100);
				if (t < 1) {
					t = 1;
				} else if (t > 255) {
					t = 255;
				}
				UVTable[ZigZag[i]] = t;
			}
			var aasf:Array = [
				1.0, 1.387039845, 1.306562965, 1.175875602,
				1.0, 0.785694958, 0.541196100, 0.275899379
			];
			i = 0;
			for (var row:int = 0; row < 8; row++)
			{
				for (var col:int = 0; col < 8; col++)
				{
					fdtbl_Y[i]  = (1.0 / (YTable [ZigZag[i]] * aasf[row] * aasf[col] * 8.0));
					fdtbl_UV[i] = (1.0 / (UVTable[ZigZag[i]] * aasf[row] * aasf[col] * 8.0));
					i++;
				}
			}
		}
	
		private var YDC_HT:Array;
		private var UVDC_HT:Array;
		private var YAC_HT:Array;
		private var UVAC_HT:Array;
	
		private function computeHuffmanTbl(nrcodes:Array, std_table:Array):Array
		{
			var codevalue:int = 0;
			var pos_in_table:int = 0;
			var HT:Array = new Array();
			for (var k:int=1; k<=16; k++) {
				for (var j:int=1; j<=nrcodes[k]; j++) {
					HT[std_table[pos_in_table]] = new BitString();
					HT[std_table[pos_in_table]].val = codevalue;
					HT[std_table[pos_in_table]].len = k;
					pos_in_table++;
					codevalue++;
				}
				codevalue*=2;
			}
			return HT;
		}
	
		private var std_dc_luminance_nrcodes:Array = [0,0,1,5,1,1,1,1,1,1,0,0,0,0,0,0,0];
		private var std_dc_luminance_values:Array = [0,1,2,3,4,5,6,7,8,9,10,11];
		private var std_ac_luminance_nrcodes:Array = [0,0,2,1,3,3,2,4,3,5,5,4,4,0,0,1,0x7d];
		private var std_ac_luminance_values:Array = [
			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
		];
	
		private var std_dc_chrominance_nrcodes:Array = [0,0,3,1,1,1,1,1,1,1,1,1,0,0,0,0,0];
		private var std_dc_chrominance_values:Array = [0,1,2,3,4,5,6,7,8,9,10,11];
		private var std_ac_chrominance_nrcodes:Array = [0,0,2,1,2,4,4,3,4,7,5,4,4,0,1,2,0x77];
		private var std_ac_chrominance_values:Array = [
			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
		];
	
		private function initHuffmanTbl():void
		{
			YDC_HT = computeHuffmanTbl(std_dc_luminance_nrcodes,std_dc_luminance_values);
			UVDC_HT = computeHuffmanTbl(std_dc_chrominance_nrcodes,std_dc_chrominance_values);
			YAC_HT = computeHuffmanTbl(std_ac_luminance_nrcodes,std_ac_luminance_values);
			UVAC_HT = computeHuffmanTbl(std_ac_chrominance_nrcodes,std_ac_chrominance_values);
		}
	
		private var bitcode:Array = new Array(65535);
		private var category:Array = new Array(65535);
	
		private function initCategoryNumber():void
		{
			var nrlower:int = 1;
			var nrupper:int = 2;
			var nr:int;
			for (var cat:int=1; cat<=15; cat++) {
				//Positive numbers
				for (nr=nrlower; nr<nrupper; nr++) {
					category[32767+nr] = cat;
					bitcode[32767+nr] = new BitString();
					bitcode[32767+nr].len = cat;
					bitcode[32767+nr].val = nr;
				}
				//Negative numbers
				for (nr=-(nrupper-1); nr<=-nrlower; nr++) {
					category[32767+nr] = cat;
					bitcode[32767+nr] = new BitString();
					bitcode[32767+nr].len = cat;
					bitcode[32767+nr].val = nrupper-1+nr;
				}
				nrlower <<= 1;
				nrupper <<= 1;
			}
		}
	
		// IO functions
	
		private var byteout:ByteArray;
		private var bytenew:int = 0;
		private var bytepos:int = 7;
	
		private function writeBits(bs:BitString):void
		{
			var value:int = bs.val;
			var posval:int = bs.len-1;
			while ( posval >= 0 ) {
				if (value & uint(1 << posval) ) {
					bytenew |= uint(1 << bytepos);
				}
				posval--;
				bytepos--;
				if (bytepos < 0) {
					if (bytenew == 0xFF) {
						writeByte(0xFF);
						writeByte(0);
					}
					else {
						writeByte(bytenew);
					}
					bytepos=7;
					bytenew=0;
				}
			}
		}
	
		private function writeByte(value:int):void
		{
			byteout.writeByte(value);
		}
	
		private function writeWord(value:int):void
		{
			writeByte((value>>8)&0xFF);
			writeByte((value   )&0xFF);
		}
	
		// DCT & quantization core
	
		private function fDCTQuant(data:Array, fdtbl:Array):Array
		{
			var tmp0:Number, tmp1:Number, tmp2:Number, tmp3:Number, tmp4:Number, tmp5:Number, tmp6:Number, tmp7:Number;
			var tmp10:Number, tmp11:Number, tmp12:Number, tmp13:Number;
			var z1:Number, z2:Number, z3:Number, z4:Number, z5:Number, z11:Number, z13:Number;
			var i:int;
			/* Pass 1: process rows. */
			var dataOff:int=0;
			for (i=0; i<8; i++) {
				tmp0 = data[dataOff+0] + data[dataOff+7];
				tmp7 = data[dataOff+0] - data[dataOff+7];
				tmp1 = data[dataOff+1] + data[dataOff+6];
				tmp6 = data[dataOff+1] - data[dataOff+6];
				tmp2 = data[dataOff+2] + data[dataOff+5];
				tmp5 = data[dataOff+2] - data[dataOff+5];
				tmp3 = data[dataOff+3] + data[dataOff+4];
				tmp4 = data[dataOff+3] - data[dataOff+4];
	
				/* Even part */
				tmp10 = tmp0 + tmp3;	/* phase 2 */
				tmp13 = tmp0 - tmp3;
				tmp11 = tmp1 + tmp2;
				tmp12 = tmp1 - tmp2;
	
				data[dataOff+0] = tmp10 + tmp11; /* phase 3 */
				data[dataOff+4] = tmp10 - tmp11;
	
				z1 = (tmp12 + tmp13) * 0.707106781; /* c4 */
				data[dataOff+2] = tmp13 + z1; /* phase 5 */
				data[dataOff+6] = tmp13 - z1;
	
				/* Odd part */
				tmp10 = tmp4 + tmp5; /* phase 2 */
				tmp11 = tmp5 + tmp6;
				tmp12 = tmp6 + tmp7;
	
				/* The rotator is modified from fig 4-8 to avoid extra negations. */
				z5 = (tmp10 - tmp12) * 0.382683433; /* c6 */
				z2 = 0.541196100 * tmp10 + z5; /* c2-c6 */
				z4 = 1.306562965 * tmp12 + z5; /* c2+c6 */
				z3 = tmp11 * 0.707106781; /* c4 */
	
				z11 = tmp7 + z3;	/* phase 5 */
				z13 = tmp7 - z3;
	
				data[dataOff+5] = z13 + z2;	/* phase 6 */
				data[dataOff+3] = z13 - z2;
				data[dataOff+1] = z11 + z4;
				data[dataOff+7] = z11 - z4;
	
				dataOff += 8; /* advance pointer to next row */
			}
	
			/* Pass 2: process columns. */
			dataOff = 0;
			for (i=0; i<8; i++) {
				tmp0 = data[dataOff+ 0] + data[dataOff+56];
				tmp7 = data[dataOff+ 0] - data[dataOff+56];
				tmp1 = data[dataOff+ 8] + data[dataOff+48];
				tmp6 = data[dataOff+ 8] - data[dataOff+48];
				tmp2 = data[dataOff+16] + data[dataOff+40];
				tmp5 = data[dataOff+16] - data[dataOff+40];
				tmp3 = data[dataOff+24] + data[dataOff+32];
				tmp4 = data[dataOff+24] - data[dataOff+32];
	
				/* Even part */
				tmp10 = tmp0 + tmp3;	/* phase 2 */
				tmp13 = tmp0 - tmp3;
				tmp11 = tmp1 + tmp2;
				tmp12 = tmp1 - tmp2;
	
				data[dataOff+ 0] = tmp10 + tmp11; /* phase 3 */
				data[dataOff+32] = tmp10 - tmp11;
	
				z1 = (tmp12 + tmp13) * 0.707106781; /* c4 */
				data[dataOff+16] = tmp13 + z1; /* phase 5 */
				data[dataOff+48] = tmp13 - z1;
	
				/* Odd part */
				tmp10 = tmp4 + tmp5; /* phase 2 */
				tmp11 = tmp5 + tmp6;
				tmp12 = tmp6 + tmp7;
	
				/* The rotator is modified from fig 4-8 to avoid extra negations. */
				z5 = (tmp10 - tmp12) * 0.382683433; /* c6 */
				z2 = 0.541196100 * tmp10 + z5; /* c2-c6 */
				z4 = 1.306562965 * tmp12 + z5; /* c2+c6 */
				z3 = tmp11 * 0.707106781; /* c4 */
	
				z11 = tmp7 + z3;	/* phase 5 */
				z13 = tmp7 - z3;
	
				data[dataOff+40] = z13 + z2; /* phase 6 */
				data[dataOff+24] = z13 - z2;
				data[dataOff+ 8] = z11 + z4;
				data[dataOff+56] = z11 - z4;
	
				dataOff++; /* advance pointer to next column */
			}
	
			// Quantize/descale the coefficients
			for (i=0; i<64; i++) {
				// Apply the quantization and scaling factor & Round to nearest integer
				data[i] = Math.round((data[i]*fdtbl[i]));
			}
			return data;
		}
	
		// Chunk writing
	
		private function writeAPP0():void
		{
			writeWord(0xFFE0); // marker
			writeWord(16); // length
			writeByte(0x4A); // J
			writeByte(0x46); // F
			writeByte(0x49); // I
			writeByte(0x46); // F
			writeByte(0); // = "JFIF",'\0'
			writeByte(1); // versionhi
			writeByte(1); // versionlo
			writeByte(0); // xyunits
			writeWord(1); // xdensity
			writeWord(1); // ydensity
			writeByte(0); // thumbnwidth
			writeByte(0); // thumbnheight
		}
	
		private function writeSOF0(width:int, height:int):void
		{
			writeWord(0xFFC0); // marker
			writeWord(17);   // length, truecolor YUV JPG
			writeByte(8);    // precision
			writeWord(height);
			writeWord(width);
			writeByte(3);    // nrofcomponents
			writeByte(1);    // IdY
			writeByte(0x11); // HVY
			writeByte(0);    // QTY
			writeByte(2);    // IdU
			writeByte(0x11); // HVU
			writeByte(1);    // QTU
			writeByte(3);    // IdV
			writeByte(0x11); // HVV
			writeByte(1);    // QTV
		}
	
		private function writeDQT():void
		{
			writeWord(0xFFDB); // marker
			writeWord(132);	   // length
			writeByte(0);
			var i:int;
			for (i=0; i<64; i++) {
				writeByte(YTable[i]);
			}
			writeByte(1);
			for (i=0; i<64; i++) {
				writeByte(UVTable[i]);
			}
		}
	
		private function writeDHT():void
		{
			writeWord(0xFFC4); // marker
			writeWord(0x01A2); // length
			var i:int;
	
			writeByte(0); // HTYDCinfo
			for (i=0; i<16; i++) {
				writeByte(std_dc_luminance_nrcodes[i+1]);
			}
			for (i=0; i<=11; i++) {
				writeByte(std_dc_luminance_values[i]);
			}
	
			writeByte(0x10); // HTYACinfo
			for (i=0; i<16; i++) {
				writeByte(std_ac_luminance_nrcodes[i+1]);
			}
			for (i=0; i<=161; i++) {
				writeByte(std_ac_luminance_values[i]);
			}
	
			writeByte(1); // HTUDCinfo
			for (i=0; i<16; i++) {
				writeByte(std_dc_chrominance_nrcodes[i+1]);
			}
			for (i=0; i<=11; i++) {
				writeByte(std_dc_chrominance_values[i]);
			}
	
			writeByte(0x11); // HTUACinfo
			for (i=0; i<16; i++) {
				writeByte(std_ac_chrominance_nrcodes[i+1]);
			}
			for (i=0; i<=161; i++) {
				writeByte(std_ac_chrominance_values[i]);
			}
		}
	
		private function writeSOS():void
		{
			writeWord(0xFFDA); // marker
			writeWord(12); // length
			writeByte(3); // nrofcomponents
			writeByte(1); // IdY
			writeByte(0); // HTY
			writeByte(2); // IdU
			writeByte(0x11); // HTU
			writeByte(3); // IdV
			writeByte(0x11); // HTV
			writeByte(0); // Ss
			writeByte(0x3f); // Se
			writeByte(0); // Bf
		}
	
		// Core processing
		private var DU:Array = new Array(64);
	
		private function processDU(CDU:Array, fdtbl:Array, DC:Number, HTDC:Array, HTAC:Array):Number
		{
			var EOB:BitString = HTAC[0x00];
			var M16zeroes:BitString = HTAC[0xF0];
			var i:int;
	
			var DU_DCT:Array = fDCTQuant(CDU, fdtbl);
			//ZigZag reorder
			for (i=0;i<64;i++) {
				DU[ZigZag[i]]=DU_DCT[i];
			}
			var Diff:int = DU[0] - DC; DC = DU[0];
			//Encode DC
			if (Diff==0) {
				writeBits(HTDC[0]); // Diff might be 0
			} else {
				writeBits(HTDC[category[32767+Diff]]);
				writeBits(bitcode[32767+Diff]);
			}
			//Encode ACs
			var end0pos:int = 63;
			for (; (end0pos>0)&&(DU[end0pos]==0); end0pos--) {
			};
			//end0pos = first element in reverse order !=0
			if ( end0pos == 0) {
				writeBits(EOB);
				return DC;
			}
			i = 1;
			while ( i <= end0pos ) {
				var startpos:int = i;
				for (; (DU[i]==0) && (i<=end0pos); i++) {
				}
				var nrzeroes:int = i-startpos;
				if ( nrzeroes >= 16 ) {
					for (var nrmarker:int=1; nrmarker <= nrzeroes/16; nrmarker++) {
						writeBits(M16zeroes);
					}
					nrzeroes = int(nrzeroes&0xF);
				}
				writeBits(HTAC[nrzeroes*16+category[32767+DU[i]]]);
				writeBits(bitcode[32767+DU[i]]);
				i++;
			}
			if ( end0pos != 63 ) {
				writeBits(EOB);
			}
			return DC;
		}
	
		private var YDU:Array = new Array(64);
		private var UDU:Array = new Array(64);
		private var VDU:Array = new Array(64);
	
		private function RGB2YUV(img:BitmapData, xpos:int, ypos:int):void
		{
			var pos:int=0;
			for (var y:int=0; y<8; y++) {
				for (var x:int=0; x<8; x++) {
					var P:uint = img.getPixel32(xpos+x,ypos+y);
					var R:Number = Number((P>>16)&0xFF);
					var G:Number = Number((P>> 8)&0xFF);
					var B:Number = Number((P    )&0xFF);
					YDU[pos]=((( 0.29900)*R+( 0.58700)*G+( 0.11400)*B))-128;
					UDU[pos]=(((-0.16874)*R+(-0.33126)*G+( 0.50000)*B));
					VDU[pos]=((( 0.50000)*R+(-0.41869)*G+(-0.08131)*B));
					pos++;
				}
			}
		}
	
		/**
		 * Constructor for JPEGEncoder class
		 *
		 * @param quality The quality level between 1 and 100 that detrmines the
		 * level of compression used in the generated JPEG
		 * @langversion ActionScript 3.0
		 * @playerversion Flash 9.0
		 * @tiptext
		 */		
		public function JPGEncoder(quality:Number = 50)
		{
			if (quality <= 0) {
				quality = 1;
			}
			if (quality > 100) {
				quality = 100;
			}
			var sf:int = 0;
			if (quality < 50) {
				sf = int(5000 / quality);
			} else {
				sf = int(200 - quality*2);
			}
			// Create tables
			initHuffmanTbl();
			initCategoryNumber();
			initQuantTables(sf);
		}
	
		/**
		 * Created a JPEG image from the specified BitmapData
		 *
		 * @param image The BitmapData that will be converted into the JPEG format.
		 * @return a ByteArray representing the JPEG encoded image data.
		 * @langversion ActionScript 3.0
		 * @playerversion Flash 9.0
		 * @tiptext
		 */	
		public function encode(image:BitmapData):ByteArray
		{
			// Initialize bit writer
			byteout = new ByteArray();
			bytenew=0;
			bytepos=7;
	
			// Add JPEG headers
			writeWord(0xFFD8); // SOI
			writeAPP0();
			writeDQT();
			writeSOF0(image.width,image.height);
			writeDHT();
			writeSOS();

	
			// Encode 8x8 macroblocks
			var DCY:Number=0;
			var DCU:Number=0;
			var DCV:Number=0;
			bytenew=0;
			bytepos=7;
			for (var ypos:int=0; ypos<image.height; ypos+=8) {
				for (var xpos:int=0; xpos<image.width; xpos+=8) {
					RGB2YUV(image, xpos, ypos);
					DCY = processDU(YDU, fdtbl_Y, DCY, YDC_HT, YAC_HT);
					DCU = processDU(UDU, fdtbl_UV, DCU, UVDC_HT, UVAC_HT);
					DCV = processDU(VDU, fdtbl_UV, DCV, UVDC_HT, UVAC_HT);
				}
			}
	
			// Do the bit alignment of the EOI marker
			if ( bytepos >= 0 ) {
				var fillbits:BitString = new BitString();
				fillbits.len = bytepos+1;
				fillbits.val = (1<<(bytepos+1))-1;
				writeBits(fillbits);
			}
	
			writeWord(0xFFD9); //EOI
			return byteout;
		}
	}
}