Package com.twelvemonkeys.imageio.plugins.hdr

Class RGBE

java.lang.Object

com.twelvemonkeys.imageio.plugins.hdr.RGBE

final class RGBE
extends java.lang.Object

This file contains code to read and write four byte rgbe file format developed by Greg Ward. It handles the conversions between rgbe and pixels consisting of floats. The data is assumed to be an array of floats. By default there are three floats per pixel in the order red, green, blue. (RGBE_DATA_??? values control this.) Only the mimimal header reading and writing is implemented. Each routine does error checking and will return a status value as defined below. This code is intended as a skeleton so feel free to modify it to suit your needs.

Ported to Java and restructured by Kenneth Russell. posted to www.graphics.cornell.edu/~bjw/ written by Bruce Walter (bjw@graphics.cornell.edu) 5/26/95 based on code written by Greg Ward

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Source

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static class	RGBE.FracExp
static class	RGBE.Header

Field Summary

Fields

Modifier and Type	Field	Description
private static java.lang.String	exposureString
private static java.lang.String	gammaString
private static double	huge
private static double	tiny
private static double	two54
private static double	twom54
private static int	VALID_EXPOSURE
private static int	VALID_GAMMA
private static int	VALID_PROGRAMTYPE
private static java.util.regex.Pattern	widthHeightPattern

Constructor Summary

Constructors

Constructor	Description
RGBE()

Method Summary

Modifier and Type	Method	Description
private static double	copysign(double x, double y)	copysign(double x, double y) copysign(x,y) returns a value with the magnitude of x and with the sign bit of y.
private static boolean	finite(double x)
static void	float2rgbe(byte[] rgbe, float red, float green, float blue)	Standard conversion from float pixels to rgbe pixels.
private static RGBE.FracExp	frexp(double x)
private static double	fromhilo(int hi, int lo)
private static int	hi(double x)
static double	ldexp(double value, int exp)
private static int	lo(double x)
static void	main(java.lang.String[] args)
static RGBE.Header	readHeader(java.io.DataInput in)
static void	readPixels(java.io.DataInput in, float[] data, int numpixels)	Simple read routine.
static void	readPixelsRaw(java.io.DataInput in, byte[] data, int offset, int numpixels)
static void	readPixelsRawRLE(java.io.DataInput in, byte[] data, int offset, int scanline_width, int num_scanlines)
static void	rgbe2float(float[] rgb, byte[] rgbe, int startRGBEOffset)	Standard conversion from rgbe to float pixels.
private static double	scalbn(double x, int n)	scalbn (double x, int n) scalbn(x,n) returns x* 2**n computed by exponent manipulation rather than by actually performing an exponentiation or a multiplication.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

VALID_PROGRAMTYPE

private static final int VALID_PROGRAMTYPE

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Constant Field Values

VALID_GAMMA

private static final int VALID_GAMMA

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Constant Field Values

VALID_EXPOSURE

private static final int VALID_EXPOSURE

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Constant Field Values

gammaString

private static final java.lang.String gammaString

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Constant Field Values

exposureString

private static final java.lang.String exposureString

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Constant Field Values

widthHeightPattern

private static final java.util.regex.Pattern widthHeightPattern

two54

private static final double two54

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Constant Field Values

twom54

private static final double twom54

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Constant Field Values

huge

private static final double huge

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Constant Field Values

tiny

private static final double tiny

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Constant Field Values

Constructor Detail

RGBE

RGBE()

Method Detail

readHeader

public static RGBE.Header readHeader(java.io.DataInput in)
                              throws java.io.IOException

Throws:

java.io.IOException

readPixels

public static void readPixels(java.io.DataInput in,
                              float[] data,
                              int numpixels)
                       throws java.io.IOException

Simple read routine. Will not correctly handle run length encoding.

Throws:

java.io.IOException

readPixelsRaw

public static void readPixelsRaw(java.io.DataInput in,
                                 byte[] data,
                                 int offset,
                                 int numpixels)
                          throws java.io.IOException

Throws:

java.io.IOException

readPixelsRawRLE

public static void readPixelsRawRLE(java.io.DataInput in,
                                    byte[] data,
                                    int offset,
                                    int scanline_width,
                                    int num_scanlines)
                             throws java.io.IOException

Throws:

java.io.IOException

float2rgbe

public static void float2rgbe(byte[] rgbe,
                              float red,
                              float green,
                              float blue)

Standard conversion from float pixels to rgbe pixels.

rgbe2float

public static void rgbe2float(float[] rgb,
                              byte[] rgbe,
                              int startRGBEOffset)

Standard conversion from rgbe to float pixels. Note: Ward uses ldexp(col+0.5,exp-(128+8)). However we wanted pixels in the range [0,1] to map back into the range [0,1].

ldexp

public static double ldexp(double value,
                           int exp)

hi

private static int hi(double x)

lo

private static int lo(double x)

fromhilo

private static double fromhilo(int hi,
                               int lo)

frexp

private static RGBE.FracExp frexp(double x)

finite

private static boolean finite(double x)

copysign

private static double copysign(double x,
                               double y)

copysign(double x, double y)
copysign(x,y) returns a value with the magnitude of x and with the sign bit of y.

scalbn

private static double scalbn(double x,
                             int n)

scalbn (double x, int n)
scalbn(x,n) returns x* 2**n computed by exponent manipulation rather than by actually performing an exponentiation or a multiplication.

main

public static void main(java.lang.String[] args)