+/*
+ * Image codec. Author: Svjatoslav Agejenko, svjatoslav@svjatoslav.eu
+ * This project is released under Creative Commons Zero (CC0) license.
+ */
package eu.svjatoslav.imagesqueeze.codec;
/**
* Compressed image pixels decoder.
*/
+import eu.svjatoslav.commons.data.BitInputStream;
+
import java.awt.image.DataBufferByte;
import java.awt.image.WritableRaster;
import java.io.IOException;
-public class ImageDecoder {
-
- int width, height;
- Image image;
+class ImageDecoder {
+
+ private final int width;
+ private final int height;
+ private final Image image;
+ private final byte[] decodedYRangeMap;
+ private final byte[] decodedYMap;
+ private final byte[] decodedURangeMap;
+ private final byte[] decodedUMap;
+ private final byte[] decodedVRangeMap;
+ private final byte[] decodedVMap;
+ private final Approximator approximator;
+ private final BitInputStream bitInputStream;
+ private final OperatingContext context = new OperatingContext();
+
+ public ImageDecoder(final Image image, final BitInputStream bitInputStream) {
+ approximator = new Approximator();
+
+ this.image = image;
+ this.bitInputStream = bitInputStream;
+
+ width = image.metaData.width;
+ height = image.metaData.height;
+
+ decodedYRangeMap = new byte[width * height];
+ decodedYRangeMap[0] = (byte) (255);
+ decodedYMap = new byte[width * height];
+
+ decodedURangeMap = new byte[width * height];
+ decodedURangeMap[0] = (byte) (255);
+ decodedUMap = new byte[width * height];
+
+ decodedVRangeMap = new byte[width * height];
+ decodedVRangeMap[0] = (byte) (255);
+ decodedVMap = new byte[width * height];
- byte [] decodedYRangeMap;
- byte [] decodedYMap;
-
- byte [] decodedURangeMap;
- byte [] decodedUMap;
-
- byte [] decodedVRangeMap;
- byte [] decodedVMap;
-
- Color tmpColor = new Color();
-
- Approximator approximator;
- BitInputStream bitInputStream;
-
- ColorStats colorStats = new ColorStats();
- OperatingContext context = new OperatingContext();
-
- public ImageDecoder (Image image, BitInputStream bitInputStream) {
- approximator = new Approximator();
-
- this.image = image;
- this.bitInputStream = bitInputStream;
-
- width = image.metaData.width;
- height = image.metaData.height;
-
- decodedYRangeMap = new byte[width * height];
- decodedYRangeMap[0] = (byte)(255);
- decodedYMap = new byte[width * height];
-
- decodedURangeMap = new byte[width * height];
- decodedURangeMap[0] = (byte)(255);
- decodedUMap = new byte[width * height];
-
- decodedVRangeMap = new byte[width * height];
- decodedVRangeMap[0] = (byte)(255);
- decodedVMap = new byte[width * height];
-
- }
-
-
- public void decode() throws IOException {
- approximator.load(bitInputStream);
- approximator.computeLookupTables();
-
- WritableRaster raster = image.bufferedImage.getRaster();
- DataBufferByte dbi = (DataBufferByte)raster.getDataBuffer();
- byte [] pixels = dbi.getData();
+ }
- // load top-, left-most pixel.
- decodedYMap[0] = (byte)bitInputStream.readBits(8);
- decodedUMap[0] = (byte)bitInputStream.readBits(8);
- decodedVMap[0] = (byte)bitInputStream.readBits(8);
-
- Color color = new Color();
- color.y = ImageEncoder.byteToInt(decodedYMap[0]);
- color.u = ImageEncoder.byteToInt(decodedUMap[0]);
- color.v = ImageEncoder.byteToInt(decodedVMap[0]);
-
- color.YUV2RGB();
-
- pixels[0] = (byte)color.r;
- pixels[0+1] = (byte)color.g;
- pixels[0+2] = (byte)color.b;
-
-
- // detect initial step
- int largestDimension;
- int initialStep = 2;
- if (width > height) {
- largestDimension = width;
- } else {
- largestDimension = height;
- }
-
- while (initialStep < largestDimension){
- initialStep = initialStep * 2;
- }
-
- grid(initialStep, pixels);
- }
-
-
- public void grid(int step, byte [] pixels) throws IOException {
-
- gridDiagonal(step / 2, step / 2, step, pixels);
- gridSquare(step / 2, 0, step, pixels);
- gridSquare(0, step / 2, step, pixels);
-
- if (step > 2) grid(step / 2, pixels);
- }
-
-
- public void gridSquare(int offsetX, int offsetY, int step, byte [] pixels) throws IOException{
-
- for (int y = offsetY; y < height; y = y + step){
- for (int x = offsetX; x < width; x = x + step){
-
-
- int halfStep = step / 2;
-
- context.initialize(image, decodedYMap, decodedUMap, decodedVMap);
- context.measureNeighborEncode(x - halfStep, y);
- context.measureNeighborEncode(x + halfStep, y);
- context.measureNeighborEncode(x, y - halfStep);
- context.measureNeighborEncode(x, y + halfStep);
-
- loadPixel(step, offsetX, offsetY, x, y, pixels,
- context.colorStats.getAverageY(),
- context.colorStats.getAverageU(),
- context.colorStats.getAverageV());
-
- }
- }
- }
-
-
- public void gridDiagonal(int offsetX, int offsetY, int step, byte [] pixels) throws IOException{
-
- for (int y = offsetY; y < height; y = y + step){
- for (int x = offsetX; x < width; x = x + step){
-
- int halfStep = step / 2;
-
- context.initialize(image, decodedYMap, decodedUMap, decodedVMap);
- context.measureNeighborEncode(x - halfStep, y - halfStep);
- context.measureNeighborEncode(x + halfStep, y - halfStep);
- context.measureNeighborEncode(x - halfStep, y + halfStep);
- context.measureNeighborEncode(x + halfStep, y + halfStep);
-
- loadPixel(step, offsetX, offsetY, x, y, pixels,
- context.colorStats.getAverageY(),
- context.colorStats.getAverageU(),
- context.colorStats.getAverageV());
-
- }
- }
- }
-
-
- public void loadPixel(int step, int offsetX, int offsetY, int x, int y, byte[] pixels,
- int averageDecodedY, int averageDecodedU, int averageDecodedV)
- throws IOException{
-
- int index = (y * width) + x;
-
- int halfStep = step / 2;
-
- int parentIndex;
- if (offsetX > 0){
- if (offsetY > 0){
- // diagonal approach
- parentIndex = ((y - halfStep) * width) + (x - halfStep);
- } else {
- // take left pixel
- parentIndex = (y * width) + (x - halfStep);
- }
- } else {
- // take upper pixel
- parentIndex = ((y - halfStep) * width) + x;
- }
+ public static int readIntegerCompressed8(final BitInputStream inputStream)
+ throws IOException {
+ if (inputStream.readBits(1) == 0)
+ return inputStream.readBits(8);
+ else
+ return inputStream.readBits(32);
+ }
+ public void decode() throws IOException {
+ approximator.load(bitInputStream);
+ approximator.computeLookupTables();
- int colorBufferIndex = index * 3;
+ final WritableRaster raster = image.bufferedImage.getRaster();
+ final DataBufferByte dbi = (DataBufferByte) raster.getDataBuffer();
+ final byte[] pixels = dbi.getData();
- Color color = new Color();
- color.y = loadChannel(decodedYRangeMap, decodedYMap, approximator.yTable, averageDecodedY, index, parentIndex);
- color.u = loadChannel(decodedURangeMap, decodedUMap, approximator.uTable, averageDecodedU, index, parentIndex);
- color.v = loadChannel(decodedVRangeMap, decodedVMap, approximator.vTable, averageDecodedV, index, parentIndex);
-
- color.YUV2RGB();
-
- pixels[colorBufferIndex] = (byte)color.r;
- pixels[colorBufferIndex+1] = (byte)color.g;
- pixels[colorBufferIndex+2] = (byte)color.b;
+ // load top-, left-most pixel.
+ decodedYMap[0] = (byte) bitInputStream.readBits(8);
+ decodedUMap[0] = (byte) bitInputStream.readBits(8);
+ decodedVMap[0] = (byte) bitInputStream.readBits(8);
- }
+ final Color color = new Color();
+ color.y = ImageEncoder.byteToInt(decodedYMap[0]);
+ color.u = ImageEncoder.byteToInt(decodedUMap[0]);
+ color.v = ImageEncoder.byteToInt(decodedVMap[0]);
+ color.YUV2RGB();
- private int loadChannel(byte [] decodedRangeMap, byte [] decodedMap, Table table, int averageDecodedValue, int index,
- int parentIndex) throws IOException {
- int decodedValue = averageDecodedValue;
+ pixels[0] = (byte) color.r;
+ pixels[0 + 1] = (byte) color.g;
+ pixels[0 + 2] = (byte) color.b;
- int inheritedRange = ImageEncoder.byteToInt(decodedRangeMap[parentIndex]);
- int computedRange = inheritedRange;
+ // detect initial step
+ int largestDimension;
+ int initialStep = 2;
+ if (width > height)
+ largestDimension = width;
+ else
+ largestDimension = height;
+
+ while (initialStep < largestDimension)
+ initialStep = initialStep * 2;
- int bitCount = table.proposeBitcountForRange(inheritedRange);
- int computedRangeBitCount = 0;
- if ( bitCount > 0){
+ grid(initialStep, pixels);
+ }
+
+ private void grid(final int step, final byte[] pixels) throws IOException {
+
+ gridDiagonal(step / 2, step / 2, step, pixels);
+ gridSquare(step / 2, 0, step, pixels);
+ gridSquare(0, step / 2, step, pixels);
- int rangeDecreases = bitInputStream.readBits(1);
- if (rangeDecreases != 0){
- computedRange = table.proposeDecreasedRange(inheritedRange);
- }
-
- decodedRangeMap[index] = (byte)computedRange;
- computedRangeBitCount = table.proposeBitcountForRange(computedRange);
-
- if (computedRangeBitCount > 0){
-
- int encodedDifference = bitInputStream.readBits(computedRangeBitCount);
-
- int decodedDifference = ImageEncoder.decodeValueFromGivenBits(encodedDifference, computedRange, computedRangeBitCount);
+ if (step > 2)
+ grid(step / 2, pixels);
+ }
+
+ private void gridDiagonal(final int offsetX, final int offsetY,
+ final int step, final byte[] pixels) throws IOException {
+
+ for (int y = offsetY; y < height; y = y + step)
+ for (int x = offsetX; x < width; x = x + step) {
+
+ final int halfStep = step / 2;
+
+ context.initialize(image, decodedYMap, decodedUMap, decodedVMap);
+ context.measureNeighborEncode(x - halfStep, y - halfStep);
+ context.measureNeighborEncode(x + halfStep, y - halfStep);
+ context.measureNeighborEncode(x - halfStep, y + halfStep);
+ context.measureNeighborEncode(x + halfStep, y + halfStep);
+
+ loadPixel(step, offsetX, offsetY, x, y, pixels,
+ context.colorStats.getAverageY(),
+ context.colorStats.getAverageU(),
+ context.colorStats.getAverageV());
+
+ }
+ }
+
+ private void gridSquare(final int offsetX, final int offsetY,
+ final int step, final byte[] pixels) throws IOException {
+
+ for (int y = offsetY; y < height; y = y + step)
+ for (int x = offsetX; x < width; x = x + step) {
+
+ final int halfStep = step / 2;
+
+ context.initialize(image, decodedYMap, decodedUMap, decodedVMap);
+ context.measureNeighborEncode(x - halfStep, y);
+ context.measureNeighborEncode(x + halfStep, y);
+ context.measureNeighborEncode(x, y - halfStep);
+ context.measureNeighborEncode(x, y + halfStep);
+
+ loadPixel(step, offsetX, offsetY, x, y, pixels,
+ context.colorStats.getAverageY(),
+ context.colorStats.getAverageU(),
+ context.colorStats.getAverageV());
+
+ }
+ }
+
+ private int loadChannel(final byte[] decodedRangeMap,
+ final byte[] decodedMap, final Table table,
+ final int averageDecodedValue, final int index,
+ final int parentIndex) throws IOException {
+ int decodedValue = averageDecodedValue;
+
+ final int inheritedRange = ImageEncoder
+ .byteToInt(decodedRangeMap[parentIndex]);
+ int computedRange = inheritedRange;
+
+ final int bitCount = table.proposeBitcountForRange(inheritedRange);
+ int computedRangeBitCount;
+ if (bitCount > 0) {
+
+ final int rangeDecreases = bitInputStream.readBits(1);
+ if (rangeDecreases != 0)
+ computedRange = table.proposeDecreasedRange(inheritedRange);
+
+ decodedRangeMap[index] = (byte) computedRange;
+ computedRangeBitCount = table
+ .proposeBitcountForRange(computedRange);
+
+ if (computedRangeBitCount > 0) {
+
+ final int encodedDifference = bitInputStream
+ .readBits(computedRangeBitCount);
+
+ final int decodedDifference = ImageEncoder
+ .decodeValueFromGivenBits(encodedDifference,
+ computedRange, computedRangeBitCount);
+
+ decodedValue = averageDecodedValue - decodedDifference;
+ if (decodedValue > 255)
+ decodedValue = 255;
+ if (decodedValue < 0)
+ decodedValue = 0;
+ }
+ } else
+ decodedRangeMap[index] = (byte) inheritedRange;
+ decodedMap[index] = (byte) decodedValue;
+ return decodedValue;
+ }
- decodedValue = averageDecodedValue - decodedDifference;
- if (decodedValue > 255) decodedValue = 255;
- if (decodedValue < 0) decodedValue = 0;
- }
- } else {
- decodedRangeMap[index] = (byte)inheritedRange;
- }
- decodedMap[index] = (byte)decodedValue;
- return decodedValue;
- }
+ private void loadPixel(final int step, final int offsetX, final int offsetY,
+ final int x, final int y, final byte[] pixels,
+ final int averageDecodedY, final int averageDecodedU,
+ final int averageDecodedV) throws IOException {
+
+ final int index = (y * width) + x;
+
+ final int halfStep = step / 2;
+
+ int parentIndex;
+ if (offsetX > 0) {
+ if (offsetY > 0)
+ // diagonal approach
+ parentIndex = ((y - halfStep) * width) + (x - halfStep);
+ else
+ // take left pixel
+ parentIndex = (y * width) + (x - halfStep);
+ } else
+ // take upper pixel
+ parentIndex = ((y - halfStep) * width) + x;
+
+ final int colorBufferIndex = index * 3;
+
+ final Color color = new Color();
+ color.y = loadChannel(decodedYRangeMap, decodedYMap,
+ approximator.yTable, averageDecodedY, index, parentIndex);
+ color.u = loadChannel(decodedURangeMap, decodedUMap,
+ approximator.uTable, averageDecodedU, index, parentIndex);
+ color.v = loadChannel(decodedVRangeMap, decodedVMap,
+ approximator.vTable, averageDecodedV, index, parentIndex);
+
+ color.YUV2RGB();
+
+ pixels[colorBufferIndex] = (byte) color.r;
+ pixels[colorBufferIndex + 1] = (byte) color.g;
+ pixels[colorBufferIndex + 2] = (byte) color.b;
+
+ }
}
projects / imagesqueeze.git / blobdiff