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Setup Huffman Table framework, decode meta groups

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This commit is contained in:
Simon Kammermeier 2022-08-29 18:00:09 +02:00
parent 008e57a7ce
commit 7ab627a754
4 changed files with 106 additions and 2 deletions
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50
imageio/imageio-webp/src/main/java/com/twelvemonkeys/imageio/plugins/webp/lossless/VP8LDecoder.java
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@ -32,6 +32,8 @@
package com.twelvemonkeys.imageio.plugins.webp.lossless;
import com.twelvemonkeys.imageio.plugins.webp.LSBBitReader;
import com.twelvemonkeys.imageio.plugins.webp.lossless.huffman.HuffmanCodeGroup;
import com.twelvemonkeys.imageio.plugins.webp.lossless.huffman.HuffmanInfo;
import com.twelvemonkeys.imageio.plugins.webp.lossless.transform.ColorIndexingTransform;
import com.twelvemonkeys.imageio.plugins.webp.lossless.transform.ColorTransform;
import com.twelvemonkeys.imageio.plugins.webp.lossless.transform.PredictorTransform;
@ -46,6 +48,8 @@ import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import static com.twelvemonkeys.imageio.util.RasterUtils.asByteRaster;
import static java.lang.Math.max;
/**
* VP8LDecoder.
@ -83,7 +87,7 @@ public final class VP8LDecoder {
}
// Read Huffman codes
readHuffmanCodes(colorCacheBits, topLevel);
HuffmanInfo huffmanInfo = readHuffmanCodes(xSize, ySize, colorCacheBits, topLevel);
ColorCache colorCache = null;
@ -191,8 +195,50 @@ public final class VP8LDecoder {
return xSize;
}
private void readHuffmanCodes(int colorCacheBits, boolean allowRecursion) {
private HuffmanInfo readHuffmanCodes(int xSize, int ySize, int colorCacheBits, boolean readMetaCodes)
throws IOException {
int huffmanGroupNum = 1;
int huffmanXSize;
int huffmanYSize;
int metaCodeBits = 0;
WritableRaster huffmanMetaCodes = null;
if (readMetaCodes && lsbBitReader.readBit() == 1) {
//read in meta codes
metaCodeBits = (int) lsbBitReader.readBits(3) + 2;
huffmanXSize = subSampleSize(xSize, metaCodeBits);
huffmanYSize = subSampleSize(ySize, metaCodeBits);
//Raster with elements as BARG (only the RG components encode the meta group)
WritableRaster packedRaster = Raster.createPackedRaster(DataBuffer.TYPE_INT, huffmanXSize, huffmanYSize,
new int[] {0x0000ff00, 0x000000ff, 0xff000000, 0x00ff0000}, null);
readVP8Lossless(asByteRaster(packedRaster), false);
int[] data = ((DataBufferInt) packedRaster.getDataBuffer()).getData();
//Max metaGroup is number of meta groups
int maxCode = Integer.MIN_VALUE;
for (int code : data) {
maxCode = max(maxCode, code & 0xffff);
}
huffmanGroupNum = maxCode + 1;
/*
New Raster with just RG components exposed as single band allowing simple access of metaGroupIndex with
x,y lookup
*/
huffmanMetaCodes = Raster.createPackedRaster(packedRaster.getDataBuffer(), huffmanXSize, huffmanYSize,
huffmanXSize, new int[] {0xffff}, null);
}
HuffmanCodeGroup[] huffmanGroups = new HuffmanCodeGroup[huffmanGroupNum];
for (int i = 0; i < huffmanGroups.length; i++) {
huffmanGroups[i] = new HuffmanCodeGroup(lsbBitReader, colorCacheBits);
}
return new HuffmanInfo(huffmanMetaCodes, metaCodeBits, huffmanGroups);
}
private static int subSampleSize(final int size, final int samplingBits) {

25
imageio/imageio-webp/src/main/java/com/twelvemonkeys/imageio/plugins/webp/lossless/huffman/HuffmanCodeGroup.java Normal file
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@ -0,0 +1,25 @@
package com.twelvemonkeys.imageio.plugins.webp.lossless.huffman;
import com.twelvemonkeys.imageio.plugins.webp.LSBBitReader;
import java.io.IOException;
public class HuffmanCodeGroup {
/**
* Used for green, backward reference length and color cache
*/
public final HuffmanTable mainCode;
public final HuffmanTable redCode;
public final HuffmanTable blueCode;
public final HuffmanTable alphaCode;
public final HuffmanTable distanceCode;
public HuffmanCodeGroup(LSBBitReader lsbBitReader, int colorCacheBits) throws IOException {
mainCode = new HuffmanTable(lsbBitReader, 256 + 24 + (colorCacheBits > 0 ? 1 << colorCacheBits : 0));
redCode = new HuffmanTable(lsbBitReader, 256);
blueCode = new HuffmanTable(lsbBitReader, 256);
alphaCode = new HuffmanTable(lsbBitReader, 256);
distanceCode = new HuffmanTable(lsbBitReader, 40);
}
}

17
imageio/imageio-webp/src/main/java/com/twelvemonkeys/imageio/plugins/webp/lossless/huffman/HuffmanInfo.java Normal file
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@ -0,0 +1,17 @@
package com.twelvemonkeys.imageio.plugins.webp.lossless.huffman;
import java.awt.image.*;
public class HuffmanInfo {
public Raster huffmanMetaCodes; //Raster allows intuitive lookup by x and y
public int metaCodeBits;
public HuffmanCodeGroup[] huffmanGroups;
public HuffmanInfo(Raster huffmanMetaCodes, int metaCodeBits, HuffmanCodeGroup[] huffmanGroups) {
this.huffmanMetaCodes = huffmanMetaCodes;
this.metaCodeBits = metaCodeBits;
this.huffmanGroups = huffmanGroups;
}
}

16
imageio/imageio-webp/src/main/java/com/twelvemonkeys/imageio/plugins/webp/lossless/huffman/HuffmanTable.java Normal file
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@ -0,0 +1,16 @@
package com.twelvemonkeys.imageio.plugins.webp.lossless.huffman;
import com.twelvemonkeys.imageio.plugins.webp.LSBBitReader;
import java.io.IOException;
public class HuffmanTable {
public HuffmanTable(LSBBitReader lsbBitReader, int alphabetSize) throws IOException {
}
}