/*
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *  under the License.
 */

package org.apache.commons.imaging.formats.jpeg.decoder;

import static org.apache.commons.imaging.common.BinaryFunctions.read2Bytes;
import static org.apache.commons.imaging.common.BinaryFunctions.readBytes;

import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.DataBuffer;
import java.awt.image.DirectColorModel;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Properties;

import org.apache.commons.imaging.ImagingException;
import org.apache.commons.imaging.bytesource.ByteSource;
import org.apache.commons.imaging.color.ColorConversions;
import org.apache.commons.imaging.common.Allocator;
import org.apache.commons.imaging.common.BinaryFileParser;
import org.apache.commons.imaging.formats.jpeg.JpegConstants;
import org.apache.commons.imaging.formats.jpeg.JpegUtils;
import org.apache.commons.imaging.formats.jpeg.segments.DhtSegment;
import org.apache.commons.imaging.formats.jpeg.segments.DhtSegment.HuffmanTable;
import org.apache.commons.imaging.formats.jpeg.segments.DqtSegment;
import org.apache.commons.imaging.formats.jpeg.segments.DqtSegment.QuantizationTable;
import org.apache.commons.imaging.formats.jpeg.segments.SofnSegment;
import org.apache.commons.imaging.formats.jpeg.segments.SosSegment;

public class JpegDecoder extends BinaryFileParser implements JpegUtils.Visitor {

    private static final int[] BAND_MASK_ARGB = { 0x00ff0000, 0x0000ff00, 0x000000ff, 0xff000000 };
    private static final int[] BAND_MASK_RGB = { 0x00ff0000, 0x0000ff00, 0x000000ff };

    /*
     * JPEG is an advanced image format that takes significant computation to decode. Keep decoding fast: - Don't allocate memory inside loops, allocate it once
     * and reuse. - Minimize calculations per pixel and per block (using lookup tables for YCbCr->RGB conversion doubled performance). - Math.round() is slow,
     * use (int)(x+0.5f) instead for positive numbers.
     */

    private static int fastRound(final float x) {
        return (int) (x + 0.5f);
    }

    /**
     * Returns the positions of where each interval in the provided array starts. The number of start positions is also the count of intervals while the number
     * of restart markers found is equal to the number of start positions minus one (because restart markers are between intervals).
     *
     * @param scanPayload array to examine
     * @return the start positions
     */
    static List<Integer> getIntervalStartPositions(final int[] scanPayload) {
        final List<Integer> intervalStarts = new ArrayList<>();
        intervalStarts.add(0);
        boolean foundFF = false;
        boolean foundD0toD7 = false;
        int pos = 0;
        while (pos < scanPayload.length) {
            if (foundFF) {
                // found 0xFF D0 .. 0xFF D7 => RST marker
                if (scanPayload[pos] >= (0xff & JpegConstants.RST0_MARKER) && scanPayload[pos] <= (0xff & JpegConstants.RST7_MARKER)) {
                    foundD0toD7 = true;
                } else { // found 0xFF followed by something else => no RST marker
                    foundFF = false;
                }
            }

            if (scanPayload[pos] == 0xFF) {
                foundFF = true;
            }

            // true if one of the RST markers was found
            if (foundFF && foundD0toD7) {
                // we need to add the position after the current position because
                // we had already read 0xFF and are now at 0xDn
                intervalStarts.add(pos + 1);
                foundFF = foundD0toD7 = false;
            }
            pos++;
        }
        return intervalStarts;
    }

    /**
     * Returns an array of JpegInputStream where each field contains the JpegInputStream for one interval.
     *
     * @param scanPayload array to read intervals from
     * @return JpegInputStreams for all intervals, at least one stream is always provided
     */
    static JpegInputStream[] splitByRstMarkers(final int[] scanPayload) {
        final List<Integer> intervalStarts = getIntervalStartPositions(scanPayload);
        // get number of intervals in payload to init an array of appropriate length
        final int intervalCount = intervalStarts.size();
        final JpegInputStream[] streams = Allocator.array(intervalCount, JpegInputStream[]::new, JpegInputStream.SHALLOW_SIZE);
        for (int i = 0; i < intervalCount; i++) {
            final int from = intervalStarts.get(i);
            final int to;
            if (i < intervalCount - 1) {
                // because each restart marker needs two bytes the end of
                // this interval is two bytes before the next interval starts
                to = intervalStarts.get(i + 1) - 2;
            } else { // the last interval ends with the array
                to = scanPayload.length;
            }
            final int[] interval = Arrays.copyOfRange(scanPayload, from, to);
            streams[i] = new JpegInputStream(interval);
        }
        return streams;
    }

    private final DqtSegment.QuantizationTable[] quantizationTables = new DqtSegment.QuantizationTable[4];
    private final DhtSegment.HuffmanTable[] huffmanDCTables = new DhtSegment.HuffmanTable[4];
    private final DhtSegment.HuffmanTable[] huffmanACTables = new DhtSegment.HuffmanTable[4];
    private SofnSegment sofnSegment;
    private SosSegment sosSegment;
    private final float[][] scaledQuantizationTables = new float[4][];
    private BufferedImage image;
    private ImagingException imageReadException;
    private IOException ioException;

    private final int[] zz = new int[64];

    private final int[] blockInt = new int[64];

    private final float[] block = new float[64];

    private boolean useTiffRgb;

    /**
     * Constructs a new instance with the default, big-endian, byte order.
     */
    public JpegDecoder() {
        // empty
    }

    private Block[] allocateMcuMemory() throws ImagingException {
        final Block[] mcu = Allocator.array(sosSegment.numberOfComponents, Block[]::new, Block.SHALLOW_SIZE);
        for (int i = 0; i < sosSegment.numberOfComponents; i++) {
            final SosSegment.Component scanComponent = sosSegment.getComponents(i);
            SofnSegment.Component frameComponent = null;
            for (int j = 0; j < sofnSegment.numberOfComponents; j++) {
                if (sofnSegment.getComponents(j).componentIdentifier == scanComponent.scanComponentSelector) {
                    frameComponent = sofnSegment.getComponents(j);
                    break;
                }
            }
            if (frameComponent == null) {
                throw new ImagingException("Invalid component");
            }
            final Block fullBlock = new Block(8 * frameComponent.horizontalSamplingFactor, 8 * frameComponent.verticalSamplingFactor);
            mcu[i] = fullBlock;
        }
        return mcu;
    }

    @Override
    public boolean beginSos() {
        return true;
    }

    public BufferedImage decode(final ByteSource byteSource) throws IOException, ImagingException {
        final JpegUtils jpegUtils = new JpegUtils();
        jpegUtils.traverseJfif(byteSource, this);
        if (imageReadException != null) {
            throw imageReadException;
        }
        if (ioException != null) {
            throw ioException;
        }
        return image;
    }

    private int decode(final JpegInputStream is, final DhtSegment.HuffmanTable huffmanTable) throws ImagingException {
        // "DECODE", section F.2.2.3, figure F.16, page 109 of T.81
        int i = 1;
        int code = is.nextBit();
        while (code > huffmanTable.getMaxCode(i)) {
            i++;
            code = code << 1 | is.nextBit();
        }
        int j = huffmanTable.getValPtr(i);
        j += code - huffmanTable.getMinCode(i);
        return huffmanTable.getHuffVal(j);
    }

    private int extend(int v, final int t) {
        // "EXTEND", section F.2.2.1, figure F.12, page 105 of T.81
        int vt = 1 << t - 1;
        if (v < vt) {
            vt = (-1 << t) + 1;
            v += vt;
        }
        return v;
    }

    private void readMcu(final JpegInputStream is, final int[] preds, final Block[] mcu) throws ImagingException {
        for (int i = 0; i < sosSegment.numberOfComponents; i++) {
            final SosSegment.Component scanComponent = sosSegment.getComponents(i);
            SofnSegment.Component frameComponent = null;
            for (int j = 0; j < sofnSegment.numberOfComponents; j++) {
                if (sofnSegment.getComponents(j).componentIdentifier == scanComponent.scanComponentSelector) {
                    frameComponent = sofnSegment.getComponents(j);
                    break;
                }
            }
            if (frameComponent == null) {
                throw new ImagingException("Invalid component");
            }
            final Block fullBlock = mcu[i];
            for (int y = 0; y < frameComponent.verticalSamplingFactor; y++) {
                for (int x = 0; x < frameComponent.horizontalSamplingFactor; x++) {
                    Arrays.fill(zz, 0);
                    // page 104 of T.81
                    final int t = decode(is, huffmanDCTables[scanComponent.dcCodingTableSelector]);
                    int diff = receive(t, is);
                    diff = extend(diff, t);
                    zz[0] = preds[i] + diff;
                    preds[i] = zz[0];

                    // "Decode_AC_coefficients", figure F.13, page 106 of T.81
                    int k = 1;
                    while (true) {
                        final int rs = decode(is, huffmanACTables[scanComponent.acCodingTableSelector]);
                        final int ssss = rs & 0xf;
                        final int rrrr = rs >> 4;
                        final int r = rrrr;

                        if (ssss == 0) {
                            if (r != 15) {
                                break;
                            }
                            k += 16;
                        } else {
                            k += r;

                            // "Decode_ZZ(k)", figure F.14, page 107 of T.81
                            zz[k] = receive(ssss, is);
                            zz[k] = extend(zz[k], ssss);

                            if (k == 63) {
                                break;
                            }
                            k++;
                        }
                    }

                    final int shift = 1 << sofnSegment.precision - 1;
                    final int max = (1 << sofnSegment.precision) - 1;

                    final float[] scaledQuantizationTable = scaledQuantizationTables[frameComponent.quantTabDestSelector];
                    ZigZag.zigZagToBlock(zz, blockInt);
                    for (int j = 0; j < 64; j++) {
                        block[j] = blockInt[j] * scaledQuantizationTable[j];
                    }
                    Dct.inverseDct8x8(block);

                    int dstRowOffset = 8 * y * 8 * frameComponent.horizontalSamplingFactor + 8 * x;
                    int srcNext = 0;
                    for (int yy = 0; yy < 8; yy++) {
                        for (int xx = 0; xx < 8; xx++) {
                            float sample = block[srcNext++];
                            sample += shift;
                            final int result;
                            if (sample < 0) {
                                result = 0;
                            } else if (sample > max) {
                                result = max;
                            } else {
                                result = fastRound(sample);
                            }
                            fullBlock.samples[dstRowOffset + xx] = result;
                        }
                        dstRowOffset += 8 * frameComponent.horizontalSamplingFactor;
                    }
                }
            }
        }
    }

    private int receive(final int ssss, final JpegInputStream is) throws ImagingException {
        // "RECEIVE", section F.2.2.4, figure F.17, page 110 of T.81
        int i = 0;
        int v = 0;
        while (i != ssss) {
            i++;
            v = (v << 1) + is.nextBit();
        }
        return v;
    }

    private void rescaleMcu(final Block[] dataUnits, final int hSize, final int vSize, final Block[] ret) {
        for (int i = 0; i < dataUnits.length; i++) {
            final Block dataUnit = dataUnits[i];
            if (dataUnit.width == hSize && dataUnit.height == vSize) {
                System.arraycopy(dataUnit.samples, 0, ret[i].samples, 0, hSize * vSize);
            } else {
                final int hScale = hSize / dataUnit.width;
                final int vScale = vSize / dataUnit.height;
                if (hScale == 2 && vScale == 2) {
                    int srcRowOffset = 0;
                    int dstRowOffset = 0;
                    for (int y = 0; y < dataUnit.height; y++) {
                        for (int x = 0; x < hSize; x++) {
                            final int sample = dataUnit.samples[srcRowOffset + (x >> 1)];
                            ret[i].samples[dstRowOffset + x] = sample;
                            ret[i].samples[dstRowOffset + hSize + x] = sample;
                        }
                        srcRowOffset += dataUnit.width;
                        dstRowOffset += 2 * hSize;
                    }
                } else {
                    // FIXME: optimize
                    int dstRowOffset = 0;
                    for (int y = 0; y < vSize; y++) {
                        for (int x = 0; x < hSize; x++) {
                            ret[i].samples[dstRowOffset + x] = dataUnit.samples[y / vScale * dataUnit.width + x / hScale];
                        }
                        dstRowOffset += hSize;
                    }
                }
            }
        }
    }

    /**
     * Sets the decoder to treat incoming data as using the RGB color model. This extension to the JPEG specification is intended to support TIFF files that use
     * JPEG compression.
     */
    public void setTiffRgb() {
        useTiffRgb = true;
    }

    @Override
    public boolean visitSegment(final int marker, final byte[] markerBytes, final int segmentLength, final byte[] segmentLengthBytes, final byte[] segmentData)
            throws ImagingException, IOException {
        final int[] sofnSegments = { JpegConstants.SOF0_MARKER, JpegConstants.SOF1_MARKER, JpegConstants.SOF2_MARKER, JpegConstants.SOF3_MARKER,
                JpegConstants.SOF5_MARKER, JpegConstants.SOF6_MARKER, JpegConstants.SOF7_MARKER, JpegConstants.SOF9_MARKER, JpegConstants.SOF10_MARKER,
                JpegConstants.SOF11_MARKER, JpegConstants.SOF13_MARKER, JpegConstants.SOF14_MARKER, JpegConstants.SOF15_MARKER, };

        if (Arrays.binarySearch(sofnSegments, marker) >= 0) {
            if (marker != JpegConstants.SOF0_MARKER) {
                throw new ImagingException("Only sequential, baseline JPEGs " + "are supported at the moment");
            }
            sofnSegment = new SofnSegment(marker, segmentData);
        } else if (marker == JpegConstants.DQT_MARKER) {
            final DqtSegment dqtSegment = new DqtSegment(marker, segmentData);
            for (final QuantizationTable table : dqtSegment.quantizationTables) {
                if (0 > table.destinationIdentifier || table.destinationIdentifier >= quantizationTables.length) {
                    throw new ImagingException("Invalid quantization table identifier " + table.destinationIdentifier);
                }
                quantizationTables[table.destinationIdentifier] = table;
                final int mSize = 64;
                final int[] quantizationMatrixInt = Allocator.intArray(mSize);
                ZigZag.zigZagToBlock(table.getElements(), quantizationMatrixInt);
                final float[] quantizationMatrixFloat = Allocator.floatArray(mSize);
                for (int j = 0; j < mSize; j++) {
                    quantizationMatrixFloat[j] = quantizationMatrixInt[j];
                }
                Dct.scaleDequantizationMatrix(quantizationMatrixFloat);
                scaledQuantizationTables[table.destinationIdentifier] = quantizationMatrixFloat;
            }
        } else if (marker == JpegConstants.DHT_MARKER) {
            final DhtSegment dhtSegment = new DhtSegment(marker, segmentData);
            for (final HuffmanTable table : dhtSegment.huffmanTables) {
                final DhtSegment.HuffmanTable[] tables;
                if (table.tableClass == 0) {
                    tables = huffmanDCTables;
                } else if (table.tableClass == 1) {
                    tables = huffmanACTables;
                } else {
                    throw new ImagingException("Invalid huffman table class " + table.tableClass);
                }
                if (0 > table.destinationIdentifier || table.destinationIdentifier >= tables.length) {
                    throw new ImagingException("Invalid huffman table identifier " + table.destinationIdentifier);
                }
                tables[table.destinationIdentifier] = table;
            }
        }
        return true;
    }

    @Override
    public void visitSos(final int marker, final byte[] markerBytes, final byte[] imageData) {
        try (ByteArrayInputStream is = new ByteArrayInputStream(imageData)) {
            // read the scan header
            final int segmentLength = read2Bytes("segmentLength", is, "Not a Valid JPEG File", getByteOrder());
            final byte[] sosSegmentBytes = readBytes("SosSegment", is, segmentLength - 2, "Not a Valid JPEG File");
            sosSegment = new SosSegment(marker, sosSegmentBytes);
            // read the payload of the scan, this is the remainder of image data after the header
            // the payload contains the entropy-encoded segments (or ECS) divided by RST markers
            // or only one ECS if the entropy-encoded data is not divided by RST markers
            // length of payload = length of image data - length of data already read
            final int[] scanPayload = Allocator.intArray(imageData.length - segmentLength);
            int payloadReadCount = 0;
            while (payloadReadCount < scanPayload.length) {
                scanPayload[payloadReadCount] = is.read();
                payloadReadCount++;
            }

            int hMax = 0;
            int vMax = 0;
            for (int i = 0; i < sofnSegment.numberOfComponents; i++) {
                hMax = Math.max(hMax, sofnSegment.getComponents(i).horizontalSamplingFactor);
                vMax = Math.max(vMax, sofnSegment.getComponents(i).verticalSamplingFactor);
            }
            final int hSize = 8 * hMax;
            final int vSize = 8 * vMax;

            final int xMCUs = (sofnSegment.width + hSize - 1) / hSize;
            final int yMCUs = (sofnSegment.height + vSize - 1) / vSize;
            final Block[] mcu = allocateMcuMemory();
            final Block[] scaledMCU = Allocator.array(mcu.length, Block[]::new, Block.SHALLOW_SIZE);
            Arrays.setAll(scaledMCU, i -> new Block(hSize, vSize));
            final int[] preds = Allocator.intArray(sofnSegment.numberOfComponents);
            final ColorModel colorModel;
            final WritableRaster raster;
            Allocator.check(Integer.BYTES * sofnSegment.width * sofnSegment.height);
            switch (sofnSegment.numberOfComponents) {
            case 4:
                // Special handling for the application-RGB case: TIFF files with
                // JPEG compression can support an alpha channel. This extension
                // to the JPEG standard is implemented by specifying a color model
                // with a fourth channel for alpha.
                if (useTiffRgb) {
                    colorModel = new DirectColorModel(32, 0x00ff0000, 0x0000ff00, 0x000000ff, 0xff000000);
                    raster = Raster.createPackedRaster(DataBuffer.TYPE_INT, sofnSegment.width, sofnSegment.height, BAND_MASK_ARGB, null);
                } else {
                    colorModel = new DirectColorModel(24, 0x00ff0000, 0x0000ff00, 0x000000ff);
                    raster = Raster.createPackedRaster(DataBuffer.TYPE_INT, sofnSegment.width, sofnSegment.height, BAND_MASK_RGB, null);
                }

                break;
            case 3:
                colorModel = new DirectColorModel(24, 0x00ff0000, 0x0000ff00, 0x000000ff);
                raster = Raster.createPackedRaster(DataBuffer.TYPE_INT, sofnSegment.width, sofnSegment.height, new int[] { 0x00ff0000, 0x0000ff00, 0x000000ff },
                        null);
                break;
            case 1:
                colorModel = new DirectColorModel(24, 0x00ff0000, 0x0000ff00, 0x000000ff);
                raster = Raster.createPackedRaster(DataBuffer.TYPE_INT, sofnSegment.width, sofnSegment.height, new int[] { 0x00ff0000, 0x0000ff00, 0x000000ff },
                        null);
                // FIXME: why do images come out too bright with CS_GRAY?
                // colorModel = new ComponentColorModel(
                // ColorSpace.getInstance(ColorSpace.CS_GRAY), false, true,
                // Transparency.OPAQUE, DataBuffer.TYPE_BYTE);
                // raster = colorModel.createCompatibleWritableRaster(
                // sofnSegment.width, sofnSegment.height);
                break;
            default:
                throw new ImagingException(sofnSegment.numberOfComponents + " components are invalid or unsupported");
            }
            final DataBuffer dataBuffer = raster.getDataBuffer();

            final JpegInputStream[] bitInputStreams = splitByRstMarkers(scanPayload);
            int bitInputStreamCount = 0;
            JpegInputStream bitInputStream = bitInputStreams[0];

            for (int y1 = 0; y1 < vSize * yMCUs; y1 += vSize) {
                for (int x1 = 0; x1 < hSize * xMCUs; x1 += hSize) {
                    // Provide the next interval if an interval is read until it's end
                    // as long there are unread intervals available
                    if (!bitInputStream.hasNext()) {
                        bitInputStreamCount++;
                        if (bitInputStreamCount < bitInputStreams.length) {
                            bitInputStream = bitInputStreams[bitInputStreamCount];
                        }
                    }

                    readMcu(bitInputStream, preds, mcu);
                    rescaleMcu(mcu, hSize, vSize, scaledMCU);
                    int srcRowOffset = 0;
                    int dstRowOffset = y1 * sofnSegment.width + x1;

                    // The TIFF-RGB logic was adapted from the original x2,y2 loops
                    // but special handling was added for TIFF-JPEG RGB colorspace
                    // and conditional checks were reorganized for efficiency
                    if (useTiffRgb && (scaledMCU.length == 3 || scaledMCU.length == 4)) {
                        // The original (legacy) coding for the x2 and y2 loop was:
                        // for(y2 = 0; y2 < vSize && y1 + y2 < sofnSegment.height; y2++)
                        // for(x2 = 0; x2 < hSize && x1 + x2 < sofnSegment.width; x2++)
                        // Here, we pre-compute the limits of the loop to reduce the
                        // overhead for the loop conditional evaluation.
                        final int x2Limit;
                        if (x1 + hSize <= sofnSegment.width) {
                            x2Limit = hSize;
                        } else {
                            x2Limit = sofnSegment.width - x1;
                        }
                        final int y2Limit;
                        if (y1 + vSize <= sofnSegment.height) {
                            y2Limit = vSize;
                        } else {
                            y2Limit = sofnSegment.height - y1;
                        }

                        if (scaledMCU.length == 4) {
                            // RGBA colorspace
                            // Although conventional JPEGs don't include an alpha channel
                            // TIFF images that use JPEG encoding may do so. For example,
                            // we have seen this variation in some false-color satellite images
                            // from the U.S. National Weather Service. Ordinary JPEG files
                            // may include an APP14 marker of type Unknowm indicating that
                            // the scaledMCU.length of 3 should be interpreted as the RGB colorspace
                            // and the 4-channel variation is interpreted as CYMK. But TIFF files
                            // use their own tags to specify colorspace and do not include the APP14 marker.
                            for (int y2 = 0; y2 < y2Limit; y2++) {
                                for (int x2 = 0; x2 < x2Limit; x2++) {
                                    final int r = scaledMCU[0].samples[srcRowOffset + x2];
                                    final int g = scaledMCU[1].samples[srcRowOffset + x2];
                                    final int b = scaledMCU[2].samples[srcRowOffset + x2];
                                    final int a = scaledMCU[3].samples[srcRowOffset + x2];
                                    final int rgb = a << 24 | r << 16 | g << 8 | b;
                                    dataBuffer.setElem(dstRowOffset + x2, rgb);
                                }
                                srcRowOffset += hSize;
                                dstRowOffset += sofnSegment.width;
                            }
                        } else {
                            // scaledMCU.length == 3, standard RGB
                            for (int y2 = 0; y2 < y2Limit; y2++) {
                                for (int x2 = 0; x2 < x2Limit; x2++) {
                                    final int r = scaledMCU[0].samples[srcRowOffset + x2];
                                    final int g = scaledMCU[1].samples[srcRowOffset + x2];
                                    final int b = scaledMCU[2].samples[srcRowOffset + x2];
                                    final int rgb = r << 16 | g << 8 | b;
                                    dataBuffer.setElem(dstRowOffset + x2, rgb);
                                }
                                srcRowOffset += hSize;
                                dstRowOffset += sofnSegment.width;
                            }
                        }
                    } else {
                        for (int y2 = 0; y2 < vSize && y1 + y2 < sofnSegment.height; y2++) {
                            for (int x2 = 0; x2 < hSize && x1 + x2 < sofnSegment.width; x2++) {
                                if (scaledMCU.length == 4) {
                                    final int c = scaledMCU[0].samples[srcRowOffset + x2];
                                    final int m = scaledMCU[1].samples[srcRowOffset + x2];
                                    final int y = scaledMCU[2].samples[srcRowOffset + x2];
                                    final int k = scaledMCU[3].samples[srcRowOffset + x2];
                                    final int rgb = ColorConversions.convertCmykToRgb(c, m, y, k);
                                    dataBuffer.setElem(dstRowOffset + x2, rgb);
                                } else if (scaledMCU.length == 3) {
                                    final int y = scaledMCU[0].samples[srcRowOffset + x2];
                                    final int cb = scaledMCU[1].samples[srcRowOffset + x2];
                                    final int cr = scaledMCU[2].samples[srcRowOffset + x2];
                                    final int rgb = YCbCrConverter.convertYCbCrToRgb(y, cb, cr);
                                    dataBuffer.setElem(dstRowOffset + x2, rgb);
                                } else if (mcu.length == 1) {
                                    final int y = scaledMCU[0].samples[srcRowOffset + x2];
                                    dataBuffer.setElem(dstRowOffset + x2, y << 16 | y << 8 | y);
                                } else {
                                    throw new ImagingException("Unsupported JPEG with " + mcu.length + " components");
                                }
                            }
                            srcRowOffset += hSize;
                            dstRowOffset += sofnSegment.width;
                        }
                    }
                }
            }
            image = new BufferedImage(colorModel, raster, colorModel.isAlphaPremultiplied(), new Properties());
            // byte[] remainder = super.getStreamBytes(is);
            // for (int i = 0; i < remainder.length; i++)
            // {
            // System.out.println("" + i + " = " +
            // Integer.toHexString(remainder[i]));
            // }
        } catch (final ImagingException imageReadEx) {
            imageReadException = imageReadEx;
        } catch (final IOException ioEx) {
            ioException = ioEx;
        } catch (final RuntimeException ex) {
            // Corrupt images can throw NPE and IOOBE
            imageReadException = new ImagingException("Error parsing JPEG", ex);
        }
    }
}
