imgdataconverter.java

jpeg2000算法实现

/*
 * CVS Identifier:
 *
 * $Id: ImgDataConverter.java,v 1.13 2001/02/27 19:16:03 grosbois Exp $ 
 *
 * Interface:           ImgDataConverter
 *
 * Description:         The abstract class for classes that provide
 *                      Image Data Convertres (int -> float, float->int).
 *
 *
 *
 * COPYRIGHT:
 * 
 * This software module was originally developed by Rapha雔 Grosbois and
 * Diego Santa Cruz (Swiss Federal Institute of Technology-EPFL); Joel
 * Askel鰂 (Ericsson Radio Systems AB); and Bertrand Berthelot, David
 * Bouchard, F閘ix Henry, Gerard Mozelle and Patrice Onno (Canon Research
 * Centre France S.A) in the course of development of the JPEG2000
 * standard as specified by ISO/IEC 15444 (JPEG 2000 Standard). This
 * software module is an implementation of a part of the JPEG 2000
 * Standard. Swiss Federal Institute of Technology-EPFL, Ericsson Radio
 * Systems AB and Canon Research Centre France S.A (collectively JJ2000
 * Partners) agree not to assert against ISO/IEC and users of the JPEG
 * 2000 Standard (Users) any of their rights under the copyright, not
 * including other intellectual property rights, for this software module
 * with respect to the usage by ISO/IEC and Users of this software module
 * or modifications thereof for use in hardware or software products
 * claiming conformance to the JPEG 2000 Standard. Those intending to use
 * this software module in hardware or software products are advised that
 * their use may infringe existing patents. The original developers of
 * this software module, JJ2000 Partners and ISO/IEC assume no liability
 * for use of this software module or modifications thereof. No license
 * or right to this software module is granted for non JPEG 2000 Standard
 * conforming products. JJ2000 Partners have full right to use this
 * software module for his/her own purpose, assign or donate this
 * software module to any third party and to inhibit third parties from
 * using this software module for non JPEG 2000 Standard conforming
 * products. This copyright notice must be included in all copies or
 * derivative works of this software module.
 * 
 * Copyright (c) 1999/2000 JJ2000 Partners.
 * */
package jj2000.j2k.image;

import jj2000.j2k.image.*;
import jj2000.j2k.*;

/**
 * This class is responsible of all data type conversions. It should be used,
 * at encoder side, between Tiler and ForwardWT modules and, at decoder side,
 * between InverseWT/CompDemixer and ImgWriter modules. The conversion is
 * realized when a block of data is requested: if source and destination data
 * type are the same one, it does nothing, else appropriate cast is done. All
 * the methods of the 'ImgData' interface are implemented by the
 * 'ImgDataAdapter' class that is the superclass of this one, so they don't
 * need to be reimplemented by subclasses.
 * */
public class ImgDataConverter extends ImgDataAdapter implements BlkImgDataSrc {

    /** The block used to request data from the source in the case that a
     * conversion seems necessary. It can be either int or float at
     * initialization time. It will be checked (and corrected if necessary) by
     * the source whenever necessary */
    private DataBlk srcBlk = new DataBlkInt();

    /** The source of image data */
    private BlkImgDataSrc src;

    /** The number of fraction bits in the casted ints */    
    private int fp;

    /**
     * Constructs a new ImgDataConverter object that operates on the specified
     * source of image data.
     *
     * @param imgSrc The source from where to get the data to be transformed
     *
     * @param fp The number of fraction bits in the casted ints
     *
     * @see BlkImgDataSrc
     * */
    public ImgDataConverter(BlkImgDataSrc imgSrc, int fp) {
        super(imgSrc);
	src = imgSrc;
        this.fp=fp;
    }

    /**
     * Constructs a new ImgDataConverter object that operates on the specified
     * source of image data.
     *
     * @param imgSrc The source from where to get the data to be transformed
     *
     * @see BlkImgDataSrc
     * */
    public ImgDataConverter(BlkImgDataSrc imgSrc) {
        super(imgSrc);
        src = imgSrc;
	fp = 0;
    }

    /**
     * Returns the position of the fixed point in the specified
     * component. This is the position of the least significant integral
     * (i.e. non-fractional) bit, which is equivalent to the number of
     * fractional bits. For instance, for fixed-point values with 2 fractional
     * bits, 2 is returned. For floating-point data this value does not apply
     * and 0 should be returned. Position 0 is the position of the least
     * significant bit in the data.
     *
     * @param c The index of the component.
     *
     * @return The position of the fixed-point, which is the same as the
     * number of fractional bits.
     * */
     public int getFixedPoint(int c){
        return fp;
     }

    /**
     * Returns, in the blk argument, a block of image data containing the
     * specifed rectangular area, in the specified component, using the
     * 'transfer type' specified in the block given as argument. The data is
     * returned, as a copy of the internal data, therefore the returned data
     * can be modified "in place".
     *
     * <P>The rectangular area to return is specified by the 'ulx', 'uly', 'w'
     * and 'h' members of the 'blk' argument, relative to the current
     * tile. These members are not modified by this method. The 'offset' of
     * the returned data is 0, and the 'scanw' is the same as the block's
     * width. See the 'DataBlk' class.
     *
     * <P>This method, in general, is less efficient than the
     * 'getInternCompData()' method since, in general, it copies the
     * data. However if the array of returned data is to be modified by the
     * caller then this method is preferable.
     *
     * <P>If the data array in 'blk' is 'null', then a new one is created. If
     * the data array is not 'null' then it is reused, and it must be large
     * enough to contain the block's data. Otherwise an 'ArrayStoreException'
     * or an 'IndexOutOfBoundsException' is thrown by the Java system.
     *
     * <P>The returned data may have its 'progressive' attribute set. In this
     * case the returned data is only an approximation of the "final" data.
     *
     * @param blk Its coordinates and dimensions specify the area to return,
     * relative to the current tile. If it contains a non-null data array,
     * then it must be large enough. If it contains a null data array a new
     * one is created. Some fields in this object are modified to return the
     * data.
     *
     * @param c The index of the component from which to get the data.
     *
     * @see #getInternCompData
     * */
    public DataBlk getCompData(DataBlk blk, int c){
        return getData(blk,c,false);
    }

    /**
     * Returns, in the blk argument, a block of image data containing the
     * specifed rectangular area, in the specified component, using the
     * 'transfer type' defined in the block given as argument. The data is
     * returned, as a reference to the internal data, if any, instead of as a
     * copy, therefore the returned data should not be modified.
     *
     * <P>The rectangular area to return is specified by the 'ulx', 'uly', 'w'
     * and 'h' members of the 'blk' argument, relative to the current
     * tile. These members are not modified by this method. The 'offset' and
     * 'scanw' of the returned data can be arbitrary. See the 'DataBlk' class.
     *
     * <P> If source data and expected data (blk) are using the same type,
     * block returned without any modification. If not appropriate cast is
     * used.
     *
     * <P>This method, in general, is more efficient than the 'getCompData()'
     * method since it may not copy the data. However if the array of returned
     * data is to be modified by the caller then the other method is probably
     * preferable.
     *
     * <P>If the data array in <tt>blk</tt> is <tt>null</tt>, then a new one
     * is created if necessary. The implementation of this interface may
     * choose to return the same array or a new one, depending on what is more
     * efficient. Therefore, the data array in <tt>blk</tt> prior to the
     * method call should not be considered to contain the returned data, a
     * new array may have been created. Instead, get the array from
     * <tt>blk</tt> after the method has returned.
     *
     * <P>The returned data may have its 'progressive' attribute set. In this
     * case the returned data is only an approximation of the "final" data.
     *
     * @param blk Its coordinates and dimensions specify the area to return,
     * relative to the current tile. Some fields in this object are modified
     * to return the data.
     *
     * @param c The index of the component from which to get the data.
     *
     * @return The requested DataBlk
     *
     * @see #getCompData
     * */
    public final DataBlk getInternCompData(DataBlk blk, int c){
        return getData(blk,c,true);
    }

    /**
     * Implements the 'getInternCompData()' and the 'getCompData()'
     * methods. The 'intern' flag signals which of the two methods should run
     * as.
     *
     * @param blk The data block to get.
     *
     * @param c The index of the component from which to get the data.
     *
     * @param intern If true behave as 'getInternCompData(). Otherwise behave
     * as 'getCompData()'
     *
     * @return The requested data block
     *
     * @see #getInternCompData
     *
     * @see #getCompData
     * */
    private DataBlk getData(DataBlk blk, int c, boolean intern) {
        DataBlk reqBlk;    // Reference to block used in request to source

	// Keep request data type
	int otype = blk.getDataType();

        if (otype == srcBlk.getDataType()) {
            // Probably requested type is same as source type
            reqBlk = blk;
        }
        else {
            // Probably requested type is not the same as source type
            reqBlk = srcBlk;
            // We need to copy requested coordinates and size
            reqBlk.ulx = blk.ulx;
            reqBlk.uly = blk.uly;
            reqBlk.w = blk.w;
            reqBlk.h = blk.h;
        }

	// Get source data block
        if (intern) {
            // We can use the intern variant
            srcBlk = src.getInternCompData(reqBlk,c);
        }
        else {
            // Do not use the intern variant. Note that this is not optimal
            // since if we are going to convert below then we could have used
            // the intern variant. But there is currently no way to know if we
            // will need to do conversion or not before getting the data.
            srcBlk = src.getCompData(reqBlk,c);
        }

	// Check if casting is needed
	if(srcBlk.getDataType()==otype){
	    return srcBlk;
	}

	int i;
	int k,kSrc,kmin;
	float mult;
	int w=srcBlk.w;
	int h=srcBlk.h;

	switch(otype){
	case DataBlk.TYPE_FLOAT: // Cast INT -> FLOAT

	    float farr[];
	    int srcIArr[];

	    // Get data array from resulting blk
	    farr = (float[]) blk.getData();
	    if (farr == null || farr.length < w*h) {
		farr = new float[w*h];
		blk.setData(farr); 
	    }
	    
	    blk.scanw = srcBlk.w;
	    blk.offset = 0;
	    blk.progressive = srcBlk.progressive;
	    srcIArr=(int[]) srcBlk.getData();
	    
	    // Cast data from source to blk
	    fp=src.getFixedPoint(c);
	    if(fp!=0){
		mult=1.0f/(1<<fp);
		for (i=h-1, k=w*h-1, kSrc =
                         srcBlk.offset+(h-1)*srcBlk.scanw+w-1; i>=0; i--) {
		    for (kmin = k-w; k>kmin; k--, kSrc--) {
			farr[k]=((srcIArr[kSrc]*mult));
		    }
		    // Jump to geggining of next line in source
		    kSrc -= srcBlk.scanw - w;
		}
	    }
	    else{
		for (i=h-1, k=w*h-1, kSrc =
                         srcBlk.offset+(h-1)*srcBlk.scanw+w-1; i>=0; i--) {
		    for (kmin = k-w; k>kmin; k--, kSrc--) {
			farr[k]=((float)(srcIArr[kSrc]));
		    }
		    // Jump to geggining of next line in source
		    kSrc -= srcBlk.scanw - w;
		}
	    }
	    break; // End of cast INT-> FLOAT

	case DataBlk.TYPE_INT: // cast FLOAT -> INT
		int iarr[];
		float srcFArr[];
    
		// Get data array from resulting blk
		iarr = (int[]) blk.getData();
		if (iarr == null || iarr.length < w*h) {
		    iarr = new int[w*h];
		    blk.setData(iarr); 
		}
		blk.scanw = srcBlk.w;
		blk.offset = 0;
		blk.progressive = srcBlk.progressive;
		srcFArr=(float[]) srcBlk.getData();
		
		// Cast data from source to blk
		if(fp!=0){
		    mult=(float)(1<<fp);
		    for (i=h-1, k=w*h-1, kSrc =
                             srcBlk.offset+(h-1)*srcBlk.scanw+w-1; i>=0; i--) {
			for (kmin = k-w; k>kmin; k--, kSrc--) {
			    if (srcFArr[kSrc] > 0.0f) {
				iarr[k] = (int) (srcFArr[kSrc]*mult+0.5f);
			    }
			    else {
				iarr[k] = (int) (srcFArr[kSrc]*mult-0.5f);
			    }
			}
			// Jump to geggining of next line in source
			kSrc -= srcBlk.scanw - w;
		    }
		}
		else{
		    for (i=h-1, k=w*h-1, kSrc =
                             srcBlk.offset+(h-1)*srcBlk.scanw+w-1; i>=0; i--) {
			for (kmin = k-w; k>kmin; k--, kSrc--) {
			    if (srcFArr[kSrc] > 0.0f) {
				iarr[k] = (int) (srcFArr[kSrc]+0.5f);
			    }
			    else {
				iarr[k] = (int) (srcFArr[kSrc]-0.5f);
			    }
			}
			// Jump to geggining of next line in source
			kSrc -= srcBlk.scanw - w;
		    }
		}
		break; // End cast FLOAT -> INT
	default:
	    throw
                new IllegalArgumentException("Only integer and float data "+
                                             "are "+
                                             "supported by JJ2000");
	}
	return blk;
    }
}