    001/*
    002 *  Licensed under the Apache License, Version 2.0 (the "License");
    003 *  you may not use this file except in compliance with the License.
    004 *  You may obtain a copy of the License at
    005 *
    006 *       http://www.apache.org/licenses/LICENSE-2.0
    007 *
    008 *  Unless required by applicable law or agreed to in writing, software
    009 *  distributed under the License is distributed on an "AS IS" BASIS,
    010 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    011 *  See the License for the specific language governing permissions and
    012 *  limitations under the License.
    013 *  under the License.
    014 */
    015
    016package org.apache.commons.imaging.formats.jpeg.decoder;
    017
    018import static org.apache.commons.imaging.common.BinaryFunctions.read2Bytes;
    019import static org.apache.commons.imaging.common.BinaryFunctions.readBytes;
    020
    021import java.awt.image.BufferedImage;
    022import java.awt.image.ColorModel;
    023import java.awt.image.DataBuffer;
    024import java.awt.image.DirectColorModel;
    025import java.awt.image.Raster;
    026import java.awt.image.WritableRaster;
    027import java.io.ByteArrayInputStream;
    028import java.io.IOException;
    029import java.util.ArrayList;
    030import java.util.Arrays;
    031import java.util.List;
    032import java.util.Properties;
    033
    034import org.apache.commons.imaging.ImageReadException;
    035import org.apache.commons.imaging.color.ColorConversions;
    036import org.apache.commons.imaging.common.BinaryFileParser;
    037import org.apache.commons.imaging.common.bytesource.ByteSource;
    038import org.apache.commons.imaging.formats.jpeg.JpegConstants;
    039import org.apache.commons.imaging.formats.jpeg.JpegUtils;
    040import org.apache.commons.imaging.formats.jpeg.segments.DhtSegment;
    041import org.apache.commons.imaging.formats.jpeg.segments.DhtSegment.HuffmanTable;
    042import org.apache.commons.imaging.formats.jpeg.segments.DqtSegment;
    043import org.apache.commons.imaging.formats.jpeg.segments.DqtSegment.QuantizationTable;
    044import org.apache.commons.imaging.formats.jpeg.segments.SofnSegment;
    045import org.apache.commons.imaging.formats.jpeg.segments.SosSegment;
    046
    047public class JpegDecoder extends BinaryFileParser implements JpegUtils.Visitor {
    048    /*
    049     * JPEG is an advanced image format that takes significant computation to
    050     * decode. Keep decoding fast: - Don't allocate memory inside loops,
    051     * allocate it once and reuse. - Minimize calculations per pixel and per
    052     * block (using lookup tables for YCbCr->RGB conversion doubled
    053     * performance). - Math.round() is slow, use (int)(x+0.5f) instead for
    054     * positive numbers.
    055     */
    056
    057    private final DqtSegment.QuantizationTable[] quantizationTables = new DqtSegment.QuantizationTable[4];
    058    private final DhtSegment.HuffmanTable[] huffmanDCTables = new DhtSegment.HuffmanTable[4];
    059    private final DhtSegment.HuffmanTable[] huffmanACTables = new DhtSegment.HuffmanTable[4];
    060    private SofnSegment sofnSegment;
    061    private SosSegment sosSegment;
    062    private final float[][] scaledQuantizationTables = new float[4][];
    063    private BufferedImage image;
    064    private ImageReadException imageReadException;
    065    private IOException ioException;
    066    private final int[] zz = new int[64];
    067    private final int[] blockInt = new int[64];
    068    private final float[] block = new float[64];
    069
    070    @Override
    071    public boolean beginSOS() {
    072        return true;
    073    }
    074
    075    @Override
    076    public void visitSOS(final int marker, final byte[] markerBytes, final byte[] imageData) {
    077        final ByteArrayInputStream is = new ByteArrayInputStream(imageData);
    078        try {
    079            // read the scan header
    080            final int segmentLength = read2Bytes("segmentLength", is,"Not a Valid JPEG File", getByteOrder());
    081            final byte[] sosSegmentBytes = readBytes("SosSegment", is, segmentLength - 2, "Not a Valid JPEG File");
    082            sosSegment = new SosSegment(marker, sosSegmentBytes);
    083            // read the payload of the scan, this is the remainder of image data after the header
    084            // the payload contains the entropy-encoded segments (or ECS) divided by RST markers
    085            // or only one ECS if the entropy-encoded data is not divided by RST markers
    086            // length of payload = length of image data - length of data already read
    087            final int[] scanPayload = new int[imageData.length - segmentLength];
    088            int payloadReadCount = 0;
    089            while (payloadReadCount < scanPayload.length) {
    090                scanPayload[payloadReadCount] = is.read();
    091                payloadReadCount++;
    092            }
    093
    094            int hMax = 0;
    095            int vMax = 0;
    096            for (int i = 0; i < sofnSegment.numberOfComponents; i++) {
    097                hMax = Math.max(hMax,
    098                        sofnSegment.getComponents(i).horizontalSamplingFactor);
    099                vMax = Math.max(vMax,
    100                        sofnSegment.getComponents(i).verticalSamplingFactor);
    101            }
    102            final int hSize = 8 * hMax;
    103            final int vSize = 8 * vMax;
    104
    105            final int xMCUs = (sofnSegment.width + hSize - 1) / hSize;
    106            final int yMCUs = (sofnSegment.height + vSize - 1) / vSize;
    107            final Block[] mcu = allocateMCUMemory();
    108            final Block[] scaledMCU = new Block[mcu.length];
    109            for (int i = 0; i < scaledMCU.length; i++) {
    110                scaledMCU[i] = new Block(hSize, vSize);
    111            }
    112            final int[] preds = new int[sofnSegment.numberOfComponents];
    113            ColorModel colorModel;
    114            WritableRaster raster;
    115            switch (sofnSegment.numberOfComponents) {
    116            case 4:
    117                colorModel = new DirectColorModel(24, 0x00ff0000, 0x0000ff00, 0x000000ff);
    118                final int[] bandMasks = new int[] { 0x00ff0000, 0x0000ff00, 0x000000ff };
    119                raster = Raster.createPackedRaster(DataBuffer.TYPE_INT, sofnSegment.width, sofnSegment.height, bandMasks, null);
    120                break;
    121            case 3:
    122                colorModel = new DirectColorModel(24, 0x00ff0000, 0x0000ff00,
    123                        0x000000ff);
    124                raster = Raster.createPackedRaster(DataBuffer.TYPE_INT,
    125                        sofnSegment.width, sofnSegment.height, new int[] {
    126                                0x00ff0000, 0x0000ff00, 0x000000ff }, null);
    127                break;
    128            case 1:
    129                colorModel = new DirectColorModel(24, 0x00ff0000, 0x0000ff00,
    130                        0x000000ff);
    131                raster = Raster.createPackedRaster(DataBuffer.TYPE_INT,
    132                        sofnSegment.width, sofnSegment.height, new int[] {
    133                                0x00ff0000, 0x0000ff00, 0x000000ff }, null);
    134                // FIXME: why do images come out too bright with CS_GRAY?
    135                // colorModel = new ComponentColorModel(
    136                // ColorSpace.getInstance(ColorSpace.CS_GRAY), false, true,
    137                // Transparency.OPAQUE, DataBuffer.TYPE_BYTE);
    138                // raster = colorModel.createCompatibleWritableRaster(
    139                // sofnSegment.width, sofnSegment.height);
    140                break;
    141            default:
    142                throw new ImageReadException(sofnSegment.numberOfComponents
    143                        + " components are invalid or unsupported");
    144            }
    145            final DataBuffer dataBuffer = raster.getDataBuffer();
    146
    147            final JpegInputStream[] bitInputStreams = splitByRstMarkers(scanPayload);
    148            int bitInputStreamCount = 0;
    149            JpegInputStream bitInputStream = bitInputStreams[0];
    150
    151            for (int y1 = 0; y1 < vSize * yMCUs; y1 += vSize) {
    152                for (int x1 = 0; x1 < hSize * xMCUs; x1 += hSize) {
    153                    // Provide the next interval if an interval is read until it's end
    154                    // as long there are unread intervals available
    155                    if (!bitInputStream.hasNext()) {
    156                        bitInputStreamCount++;
    157                        if (bitInputStreamCount < bitInputStreams.length) {
    158                            bitInputStream = bitInputStreams[bitInputStreamCount];
    159                        }
    160                    }
    161
    162                    readMCU(bitInputStream, preds, mcu);
    163                    rescaleMCU(mcu, hSize, vSize, scaledMCU);
    164                    int srcRowOffset = 0;
    165                    int dstRowOffset = y1 * sofnSegment.width + x1;
    166                    for (int y2 = 0; y2 < vSize && y1 + y2 < sofnSegment.height; y2++) {
    167                        for (int x2 = 0; x2 < hSize
    168                                && x1 + x2 < sofnSegment.width; x2++) {
    169                            if (scaledMCU.length == 4) {
    170                                final int C = scaledMCU[0].samples[srcRowOffset + x2];
    171                                final int M = scaledMCU[1].samples[srcRowOffset + x2];
    172                                final int Y = scaledMCU[2].samples[srcRowOffset + x2];
    173                                final int K = scaledMCU[3].samples[srcRowOffset + x2];
    174                                final int rgb = ColorConversions.convertCMYKtoRGB(C, M, Y, K);
    175                                dataBuffer.setElem(dstRowOffset + x2, rgb);
    176                            } else if (scaledMCU.length == 3) {
    177                                final int Y = scaledMCU[0].samples[srcRowOffset + x2];
    178                                final int Cb = scaledMCU[1].samples[srcRowOffset + x2];
    179                                final int Cr = scaledMCU[2].samples[srcRowOffset + x2];
    180                                final int rgb = YCbCrConverter.convertYCbCrToRGB(Y,
    181                                        Cb, Cr);
    182                                dataBuffer.setElem(dstRowOffset + x2, rgb);
    183                            } else if (mcu.length == 1) {
    184                                final int Y = scaledMCU[0].samples[srcRowOffset + x2];
    185                                dataBuffer.setElem(dstRowOffset + x2, (Y << 16)
    186                                        | (Y << 8) | Y);
    187                            } else {
    188                                throw new ImageReadException(
    189                                        "Unsupported JPEG with " + mcu.length
    190                                                + " components");
    191                            }
    192                        }
    193                        srcRowOffset += hSize;
    194                        dstRowOffset += sofnSegment.width;
    195                    }
    196                }
    197            }
    198            image = new BufferedImage(colorModel, raster,
    199                    colorModel.isAlphaPremultiplied(), new Properties());
    200            // byte[] remainder = super.getStreamBytes(is);
    201            // for (int i = 0; i < remainder.length; i++)
    202            // {
    203            // System.out.println("" + i + " = " +
    204            // Integer.toHexString(remainder[i]));
    205            // }
    206        } catch (final ImageReadException imageReadEx) {
    207            imageReadException = imageReadEx;
    208        } catch (final IOException ioEx) {
    209            ioException = ioEx;
    210        } catch (final RuntimeException ex) {
    211            // Corrupt images can throw NPE and IOOBE
    212            imageReadException = new ImageReadException("Error parsing JPEG",ex);
    213        }
    214    }
    215
    216    @Override
    217    public boolean visitSegment(final int marker, final byte[] markerBytes,
    218            final int segmentLength, final byte[] segmentLengthBytes, final byte[] segmentData)
    219            throws ImageReadException, IOException {
    220        final int[] sofnSegments = {
    221                JpegConstants.SOF0_MARKER,
    222                JpegConstants.SOF1_MARKER,
    223                JpegConstants.SOF2_MARKER,
    224                JpegConstants.SOF3_MARKER,
    225                JpegConstants.SOF5_MARKER,
    226                JpegConstants.SOF6_MARKER,
    227                JpegConstants.SOF7_MARKER,
    228                JpegConstants.SOF9_MARKER,
    229                JpegConstants.SOF10_MARKER,
    230                JpegConstants.SOF11_MARKER,
    231                JpegConstants.SOF13_MARKER,
    232                JpegConstants.SOF14_MARKER,
    233                JpegConstants.SOF15_MARKER,
    234        };
    235
    236        if (Arrays.binarySearch(sofnSegments, marker) >= 0) {
    237            if (marker != JpegConstants.SOF0_MARKER) {
    238                throw new ImageReadException("Only sequential, baseline JPEGs "
    239                        + "are supported at the moment");
    240            }
    241            sofnSegment = new SofnSegment(marker, segmentData);
    242        } else if (marker == JpegConstants.DQT_MARKER) {
    243            final DqtSegment dqtSegment = new DqtSegment(marker, segmentData);
    244            for (final QuantizationTable table : dqtSegment.quantizationTables) {
    245                if (0 > table.destinationIdentifier
    246                        || table.destinationIdentifier >= quantizationTables.length) {
    247                    throw new ImageReadException(
    248                            "Invalid quantization table identifier "
    249                                    + table.destinationIdentifier);
    250                }
    251                quantizationTables[table.destinationIdentifier] = table;
    252                final int[] quantizationMatrixInt = new int[64];
    253                ZigZag.zigZagToBlock(table.getElements(), quantizationMatrixInt);
    254                final float[] quantizationMatrixFloat = new float[64];
    255                for (int j = 0; j < 64; j++) {
    256                    quantizationMatrixFloat[j] = quantizationMatrixInt[j];
    257                }
    258                Dct.scaleDequantizationMatrix(quantizationMatrixFloat);
    259                scaledQuantizationTables[table.destinationIdentifier] = quantizationMatrixFloat;
    260            }
    261        } else if (marker == JpegConstants.DHT_MARKER) {
    262            final DhtSegment dhtSegment = new DhtSegment(marker, segmentData);
    263            for (final HuffmanTable table : dhtSegment.huffmanTables) {
    264                DhtSegment.HuffmanTable[] tables;
    265                if (table.tableClass == 0) {
    266                    tables = huffmanDCTables;
    267                } else if (table.tableClass == 1) {
    268                    tables = huffmanACTables;
    269                } else {
    270                    throw new ImageReadException("Invalid huffman table class "
    271                            + table.tableClass);
    272                }
    273                if (0 > table.destinationIdentifier
    274                        || table.destinationIdentifier >= tables.length) {
    275                    throw new ImageReadException(
    276                            "Invalid huffman table identifier "
    277                                    + table.destinationIdentifier);
    278                }
    279                tables[table.destinationIdentifier] = table;
    280            }
    281        }
    282        return true;
    283    }
    284
    285    private void rescaleMCU(final Block[] dataUnits, final int hSize, final int vSize, final Block[] ret) {
    286        for (int i = 0; i < dataUnits.length; i++) {
    287            final Block dataUnit = dataUnits[i];
    288            if (dataUnit.width == hSize && dataUnit.height == vSize) {
    289                System.arraycopy(dataUnit.samples, 0, ret[i].samples, 0, hSize
    290                        * vSize);
    291            } else {
    292                final int hScale = hSize / dataUnit.width;
    293                final int vScale = vSize / dataUnit.height;
    294                if (hScale == 2 && vScale == 2) {
    295                    int srcRowOffset = 0;
    296                    int dstRowOffset = 0;
    297                    for (int y = 0; y < dataUnit.height; y++) {
    298                        for (int x = 0; x < hSize; x++) {
    299                            final int sample = dataUnit.samples[srcRowOffset + (x >> 1)];
    300                            ret[i].samples[dstRowOffset + x] = sample;
    301                            ret[i].samples[dstRowOffset + hSize + x] = sample;
    302                        }
    303                        srcRowOffset += dataUnit.width;
    304                        dstRowOffset += 2 * hSize;
    305                    }
    306                } else {
    307                    // FIXME: optimize
    308                    int dstRowOffset = 0;
    309                    for (int y = 0; y < vSize; y++) {
    310                        for (int x = 0; x < hSize; x++) {
    311                            ret[i].samples[dstRowOffset + x] = dataUnit.samples[(y / vScale)
    312                                    * dataUnit.width + (x / hScale)];
    313                        }
    314                        dstRowOffset += hSize;
    315                    }
    316                }
    317            }
    318        }
    319    }
    320
    321    private Block[] allocateMCUMemory() throws ImageReadException {
    322        final Block[] mcu = new Block[sosSegment.numberOfComponents];
    323        for (int i = 0; i < sosSegment.numberOfComponents; i++) {
    324            final SosSegment.Component scanComponent = sosSegment.getComponents(i);
    325            SofnSegment.Component frameComponent = null;
    326            for (int j = 0; j < sofnSegment.numberOfComponents; j++) {
    327                if (sofnSegment.getComponents(j).componentIdentifier == scanComponent.scanComponentSelector) {
    328                    frameComponent = sofnSegment.getComponents(j);
    329                    break;
    330                }
    331            }
    332            if (frameComponent == null) {
    333                throw new ImageReadException("Invalid component");
    334            }
    335            final Block fullBlock = new Block(
    336                    8 * frameComponent.horizontalSamplingFactor,
    337                    8 * frameComponent.verticalSamplingFactor);
    338            mcu[i] = fullBlock;
    339        }
    340        return mcu;
    341    }
    342
    343    private void readMCU(final JpegInputStream is, final int[] preds, final Block[] mcu)
    344            throws ImageReadException {
    345        for (int i = 0; i < sosSegment.numberOfComponents; i++) {
    346            final SosSegment.Component scanComponent = sosSegment.getComponents(i);
    347            SofnSegment.Component frameComponent = null;
    348            for (int j = 0; j < sofnSegment.numberOfComponents; j++) {
    349                if (sofnSegment.getComponents(j).componentIdentifier == scanComponent.scanComponentSelector) {
    350                    frameComponent = sofnSegment.getComponents(j);
    351                    break;
    352                }
    353            }
    354            if (frameComponent == null) {
    355                throw new ImageReadException("Invalid component");
    356            }
    357            final Block fullBlock = mcu[i];
    358            for (int y = 0; y < frameComponent.verticalSamplingFactor; y++) {
    359                for (int x = 0; x < frameComponent.horizontalSamplingFactor; x++) {
    360                    Arrays.fill(zz, 0);
    361                    // page 104 of T.81
    362                    final int t = decode(
    363                            is,
    364                            huffmanDCTables[scanComponent.dcCodingTableSelector]);
    365                    int diff = receive(t, is);
    366                    diff = extend(diff, t);
    367                    zz[0] = preds[i] + diff;
    368                    preds[i] = zz[0];
    369
    370                    // "Decode_AC_coefficients", figure F.13, page 106 of T.81
    371                    int k = 1;
    372                    while (true) {
    373                        final int rs = decode(
    374                                is,
    375                                huffmanACTables[scanComponent.acCodingTableSelector]);
    376                        final int ssss = rs & 0xf;
    377                        final int rrrr = rs >> 4;
    378                        final int r = rrrr;
    379
    380                        if (ssss == 0) {
    381                            if (r != 15) {
    382                                break;
    383                            }
    384                            k += 16;
    385                        } else {
    386                            k += r;
    387
    388                            // "Decode_ZZ(k)", figure F.14, page 107 of T.81
    389                            zz[k] = receive(ssss, is);
    390                            zz[k] = extend(zz[k], ssss);
    391
    392                            if (k == 63) {
    393                                break;
    394                            }
    395                            k++;
    396                        }
    397                    }
    398
    399                    final int shift = (1 << (sofnSegment.precision - 1));
    400                    final int max = (1 << sofnSegment.precision) - 1;
    401
    402                    final float[] scaledQuantizationTable = scaledQuantizationTables[frameComponent.quantTabDestSelector];
    403                    ZigZag.zigZagToBlock(zz, blockInt);
    404                    for (int j = 0; j < 64; j++) {
    405                        block[j] = blockInt[j] * scaledQuantizationTable[j];
    406                    }
    407                    Dct.inverseDCT8x8(block);
    408
    409                    int dstRowOffset = 8 * y * 8
    410                            * frameComponent.horizontalSamplingFactor + 8 * x;
    411                    int srcNext = 0;
    412                    for (int yy = 0; yy < 8; yy++) {
    413                        for (int xx = 0; xx < 8; xx++) {
    414                            float sample = block[srcNext++];
    415                            sample += shift;
    416                            int result;
    417                            if (sample < 0) {
    418                                result = 0;
    419                            } else if (sample > max) {
    420                                result = max;
    421                            } else {
    422                                result = fastRound(sample);
    423                            }
    424                            fullBlock.samples[dstRowOffset + xx] = result;
    425                        }
    426                        dstRowOffset += 8 * frameComponent.horizontalSamplingFactor;
    427                    }
    428                }
    429            }
    430        }
    431    }
    432
    433    /**
    434     * Returns an array of JpegInputStream where each field contains the JpegInputStream
    435     * for one interval.
    436     * @param scanPayload array to read intervals from
    437     * @return JpegInputStreams for all intervals, at least one stream is always provided
    438     */
    439    static JpegInputStream[] splitByRstMarkers(final int[] scanPayload) {
    440        final List<Integer> intervalStarts = getIntervalStartPositions(scanPayload);
    441        // get number of intervals in payload to init an array of appropriate length
    442        final int intervalCount = intervalStarts.size();
    443        final JpegInputStream[] streams = new JpegInputStream[intervalCount];
    444        for (int i = 0; i < intervalCount; i++) {
    445            final int from = intervalStarts.get(i);
    446            int to;
    447            if (i < intervalCount - 1) {
    448                // because each restart marker needs two bytes the end of
    449                // this interval is two bytes before the next interval starts
    450                to = intervalStarts.get(i + 1) - 2;
    451            } else { // the last interval ends with the array
    452                to = scanPayload.length;
    453            }
    454            final int[] interval = Arrays.copyOfRange(scanPayload, from, to);
    455            streams[i] = new JpegInputStream(interval);
    456        }
    457        return streams;
    458    }
    459
    460    /**
    461     * Returns the positions of where each interval in the provided array starts. The number
    462     * of start positions is also the count of intervals while the number of restart markers
    463     * found is equal to the number of start positions minus one (because restart markers
    464     * are between intervals).
    465     *
    466     * @param scanPayload array to examine
    467     * @return the start positions
    468     */
    469    static List<Integer> getIntervalStartPositions(final int[] scanPayload) {
    470        final List<Integer> intervalStarts = new ArrayList<>();
    471        intervalStarts.add(0);
    472        boolean foundFF = false;
    473        boolean foundD0toD7 = false;
    474        int pos = 0;
    475        while (pos < scanPayload.length) {
    476            if (foundFF) {
    477                // found 0xFF D0 .. 0xFF D7 => RST marker
    478                if (scanPayload[pos] >= (0xff & JpegConstants.RST0_MARKER) &&
    479                    scanPayload[pos] <= (0xff & JpegConstants.RST7_MARKER)) {
    480                    foundD0toD7 = true;
    481                } else { // found 0xFF followed by something else => no RST marker
    482                    foundFF = false;
    483                }
    484            }
    485
    486            if (scanPayload[pos] == 0xFF) {
    487                foundFF = true;
    488            }
    489
    490            // true if one of the RST markers was found
    491            if (foundFF && foundD0toD7) {
    492                // we need to add the position after the current position because
    493                // we had already read 0xFF and are now at 0xDn
    494                intervalStarts.add(pos + 1);
    495                foundFF = foundD0toD7 = false;
    496            }
    497            pos++;
    498        }
    499        return intervalStarts;
    500    }
    501
    502    private static int fastRound(final float x) {
    503        return (int) (x + 0.5f);
    504    }
    505
    506    private int extend(int v, final int t) {
    507        // "EXTEND", section F.2.2.1, figure F.12, page 105 of T.81
    508        int vt = (1 << (t - 1));
    509        if (v < vt) {
    510            vt = (-1 << t) + 1;
    511            v += vt;
    512        }
    513        return v;
    514    }
    515
    516    private int receive(final int ssss, final JpegInputStream is) throws ImageReadException {
    517        // "RECEIVE", section F.2.2.4, figure F.17, page 110 of T.81
    518        int i = 0;
    519        int v = 0;
    520        while (i != ssss) {
    521            i++;
    522            v = (v << 1) + is.nextBit();
    523        }
    524        return v;
    525    }
    526
    527    private int decode(final JpegInputStream is, final DhtSegment.HuffmanTable huffmanTable)
    528            throws ImageReadException {
    529        // "DECODE", section F.2.2.3, figure F.16, page 109 of T.81
    530        int i = 1;
    531        int code = is.nextBit();
    532        while (code > huffmanTable.getMaxCode(i)) {
    533            i++;
    534            code = (code << 1) | is.nextBit();
    535        }
    536        int j = huffmanTable.getValPtr(i);
    537        j += code - huffmanTable.getMinCode(i);
    538        return huffmanTable.getHuffVal(j);
    539    }
    540
    541    public BufferedImage decode(final ByteSource byteSource) throws IOException,
    542            ImageReadException {
    543        final JpegUtils jpegUtils = new JpegUtils();
    544        jpegUtils.traverseJFIF(byteSource, this);
    545        if (imageReadException != null) {
    546            throw imageReadException;
    547        }
    548        if (ioException != null) {
    549            throw ioException;
    550        }
    551        return image;
    552    }
    553}