src/main/java/org/apache/xmlgraphics/image/codec/png/PNGImageDecoder.java [1306:1383]:
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        try {
            int length = chunk.getLength() - textIndex;
            byte[] data = chunk.getData();
            InputStream cis =
                new ByteArrayInputStream(data, textIndex, length);
            InputStream iis = new InflaterInputStream(cis);

            int c;
            while ((c = iis.read()) != -1) {
                value.append((char)c);
            }

            ztextKeys.add(key.toString());
            ztextStrings.add(value.toString());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private WritableRaster createRaster(int width, int height, int bands,
                                        int scanlineStride,
                                        int bitDepth) {

        DataBuffer dataBuffer;
        WritableRaster ras = null;
        Point origin = new Point(0, 0);
        if ((bitDepth < 8) && (bands == 1)) {
            dataBuffer = new DataBufferByte(height * scanlineStride);
            ras = Raster.createPackedRaster(dataBuffer,
                                            width, height,
                                            bitDepth,
                                            origin);
        } else if (bitDepth <= 8) {
            dataBuffer = new DataBufferByte(height * scanlineStride);
           ras = Raster.createInterleavedRaster(dataBuffer,
                                                 width, height,
                                                 scanlineStride,
                                                 bands,
                                                 bandOffsets[bands],
                                                 origin);
        } else {
            dataBuffer = new DataBufferUShort(height * scanlineStride);
            ras = Raster.createInterleavedRaster(dataBuffer,
                                                 width, height,
                                                 scanlineStride,
                                                 bands,
                                                 bandOffsets[bands],
                                                 origin);
        }

        return ras;
    }

    // Data filtering methods

    private static void decodeSubFilter(byte[] curr, int count, int bpp) {
        for (int i = bpp; i < count; i++) {
            int val;

            val = curr[i] & 0xff;
            val += curr[i - bpp] & 0xff;

            curr[i] = (byte)val;
        }
    }

    private static void decodeUpFilter(byte[] curr, byte[] prev,
                                       int count) {
        for (int i = 0; i < count; i++) {
            int raw = curr[i] & 0xff;
            int prior = prev[i] & 0xff;

            curr[i] = (byte)(raw + prior);
        }
    }

    private static void decodeAverageFilter(byte[] curr, byte[] prev,
                                            int count, int bpp) {
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src/main/java/org/apache/xmlgraphics/image/codec/png/PNGRed.java [1351:1428]:
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        try {
            int length = chunk.getLength() - textIndex;
            byte[] data = chunk.getData();
            InputStream cis =
                new ByteArrayInputStream(data, textIndex, length);
            InputStream iis = new InflaterInputStream(cis);

            int c;
            while ((c = iis.read()) != -1) {
                value.append((char)c);
            }

            ztextKeys.add(key.toString());
            ztextStrings.add(value.toString());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private WritableRaster createRaster(int width, int height, int bands,
                                        int scanlineStride,
                                        int bitDepth) {

        DataBuffer dataBuffer;
        WritableRaster ras = null;
        Point origin = new Point(0, 0);
        if ((bitDepth < 8) && (bands == 1)) {
            dataBuffer = new DataBufferByte(height * scanlineStride);
            ras = Raster.createPackedRaster(dataBuffer,
                                            width, height,
                                            bitDepth,
                                            origin);
        } else if (bitDepth <= 8) {
            dataBuffer = new DataBufferByte(height * scanlineStride);
           ras = Raster.createInterleavedRaster(dataBuffer,
                                                 width, height,
                                                 scanlineStride,
                                                 bands,
                                                 bandOffsets[bands],
                                                 origin);
        } else {
            dataBuffer = new DataBufferUShort(height * scanlineStride);
            ras = Raster.createInterleavedRaster(dataBuffer,
                                                 width, height,
                                                 scanlineStride,
                                                 bands,
                                                 bandOffsets[bands],
                                                 origin);
        }

        return ras;
    }

    // Data filtering methods

    private static void decodeSubFilter(byte[] curr, int count, int bpp) {
        for (int i = bpp; i < count; i++) {
            int val;

            val = curr[i] & 0xff;
            val += curr[i - bpp] & 0xff;

            curr[i] = (byte)val;
        }
    }

    private static void decodeUpFilter(byte[] curr, byte[] prev,
                                       int count) {
        for (int i = 0; i < count; i++) {
            int raw   = curr[i] & 0xff;
            int prior = prev[i] & 0xff;

            curr[i] = (byte)(raw + prior);
        }
    }

    private static void decodeAverageFilter(byte[] curr, byte[] prev,
                                            int count, int bpp) {
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