Class LogLuvConversion


  • public class LogLuvConversion
    extends Object
    Convert from LogLuv color representation to RGB color space and from LogL to grayscale.

    This implementation is based on the file tif_luv.c which is part of the TIFF library libtiff. The original implementation was written by Greg W. Larson.

    Learn more about the color type and its encoding on Greg's page LogLuv Encoding for TIFF Images.

    Since:
    0.10.0
    Author:
    Marco Schmidt
    • Constructor Detail

      • LogLuvConversion

        private LogLuvConversion()
    • Method Detail

      • convertLogL10toY

        public static double convertLogL10toY​(int p10)
        Converts an unsigned 10 bit value (the argument must lie in the interval 0 to 1023) to a double luminance (brightness) value between 0.0 and 1.0. This conversion is needed by both LogLuv to XYZ and LogL to grayscale.
        Parameters:
        p10 - input LogL value
        Returns:
        double value with luminance, between 0 and 1
      • convertLogL16toY

        public static double convertLogL16toY​(int p16)
        Converts a signed 16 bit value (the argument must lie in the interval -32768 to 32767) to a double luminance (brightness) value between 0.0 and 1.0. This conversion is needed by both LogLuv to XYZ and LogL to grayscale.
        Parameters:
        p16 - input LogL value
        Returns:
        double value with luminance, between 0 and 1
      • convertDoubleToByte

        private static byte convertDoubleToByte​(double d)
      • convertLogLuv24InterleavedtoRGB24Planar

        public static void convertLogLuv24InterleavedtoRGB24Planar​(byte[] logluv,
                                                                   byte[] red,
                                                                   byte[] green,
                                                                   byte[] blue,
                                                                   int num)
        Converts a number of 24 bit LogLuv pixels to 24 bit RGB pixels. Each LogLuv pixel is stored as three consecutive bytes in the logluv byte array. The first byte and the top two bits of the second are the LogL value, the remaining 14 bits are an index that encodes u and v.
        Parameters:
        logluv - byte array with LogLuv data, must be at least num * 3 bytes large
        red - the byte samples for the red channel will be written to this array
        green - the byte samples for the green channel will be written to this array
        blue - the byte samples for the blue channel will be written to this array
        num - number of pixels to be converted
      • convertLogLuv32InterleavedtoRGB24Planar

        public static void convertLogLuv32InterleavedtoRGB24Planar​(byte[] logluv,
                                                                   byte[] red,
                                                                   byte[] green,
                                                                   byte[] blue,
                                                                   int num)
        Converts a number of 32 bit LogLuv pixels to 24 bit RGB pixels. Each LogLuv pixel is stored as four consecutive bytes in the logluv byte array. The first two bytes represent the LogL value (most significant bytefirst), followed by the u value and then the v value.
        Parameters:
        logluv - byte array with LogLuv data, must be at least num * 4 bytes large
        red - the byte samples for the red channel will be written to this array
        green - the byte samples for the green channel will be written to this array
        blue - the byte samples for the blue channel will be written to this array
        num - number of pixels to be converted
      • convertLogL16toGray8

        public static void convertLogL16toGray8​(byte[] logl,
                                                byte[] gray,
                                                int num)
        Converts a number of 16 bit LogL samples to 8 bit grayscale samples.
        Parameters:
        logl - byte array with LogL samples, each 16 bit sample is stored as two consecutive bytes in order most-significant-byte least-significant-byte (network byte order); the array must be at least num * 2 entries large
        gray - the byte array to which the converted samples will be written
        num - the number of samples to be converted