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/*
 * Gray8QmSum.java
 *
 * Created on August 27, 2006, 9:02 AM
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 *
 * Copyright 2007 by Jon A. Webb
 *     This program is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU Lesser General Public License as published by
 *    the Free Software Foundation, either version 3 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Lesser General Public License for more details.
 *
 *    You should have received a copy of the Lesser GNU General Public License
 *    along with this program.  If not, see .
 *
 */

package com.github.ojil.algorithm;
import com.github.ojil.core.Error;
import com.github.ojil.core.Gray32Image;
import com.github.ojil.core.Gray8Image;
import com.github.ojil.core.Image;
import com.github.ojil.core.PipelineStage;
/**
 * Gray8QmSum forms the cumulative sum of an image.
 *  Output(i,j) = ∑_{k ≤ i, l ≤ j} Input(k,l). 
 *  Output is a 32-bit gray image.
 *  Input is an 8-bit gray image.
 * Note that since the output is 32 bits the input image cannot have more than
 * 2²⁴ pixels without risking overflow. For example, an image larger than
 * 4096 × 4096 (=2¹² × 2¹²) might overflow.
 * @author webb
 */
public class Gray8QmSum extends PipelineStage {
    
    /**
     * Creates a new instance of Gray8QmSum
     */
    public Gray8QmSum() {
    }
    
    /** Forms the cumulative sum of an image.
     *  Output(i,j) = ∑_{k ≤ i, l ≤ j} Input(k,l)).
     *  Output is 32-bit gray image.
     *  Input is 8-bit gray image.
     *
     * @param image the input image.
     * @throws com.github.ojil.core.Error if the input is not a Gray8Image
     */
    public void push(Image image) throws com.github.ojil.core.Error {
        if (!(image instanceof Gray8Image)) {
            throw new Error(
            				Error.PACKAGE.ALGORITHM,
            				ErrorCodes.IMAGE_NOT_GRAY8IMAGE,
            				image.toString(),
            				null,
            				null);
        }
        Gray8Image gray = (Gray8Image) image;
        Gray32Image gray32 = new Gray32Image(image.getWidth(), image.getHeight());
        Byte[] grayData = gray.getData();
        Integer[] gray32Data = gray32.getData();
        // First row
        int nSum = 0;
        for (int j=0; j