com.github.ojil.algorithm.RgbMinDiff Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of ojil-core Show documentation
Open Java Imaging Library.
There is a newer version: 0.0.11
/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package com.github.ojil.algorithm;

import com.github.ojil.core.Error;
import com.github.ojil.core.Gray8Image;
import com.github.ojil.core.Image;
import com.github.ojil.core.PipelineStage;
import com.github.ojil.core.RgbImage;
import com.github.ojil.core.RgbVal;

/**
 * Compute the Gray8Image that is the minimum absolute difference in red, green,
 * or blue between the RgbImage specified in the constructor and the RgbImage
 * supplied to the pipeline stage. This is intended to be used as part of a 
 * pipeline for separating out a fixed background from the new input. Since
 * the background can vary due to lighting conditions we find the maximum 
 * difference in any color channel and output that, making it easier to find
 * objects that may match the background in one or two channels.
 * @author webb
 */
public class RgbMinDiff extends PipelineStage {
    private RgbImage rgbBack;

    /**
     * Set background image.
     * @param rgbBack background RgbImage.
     */
    public RgbMinDiff(RgbImage rgbBack) {
        this.rgbBack = rgbBack;
    }
    
    /**
     * Process a foreground RgbImage and produce a Gray8Image in which each
     * pixel is the maximum of the differences between the input image and
     * the background image in the three color channels.
     * @param imInput input RgbImage
     * @throws com.github.ojil.core.Error if imInput is not an RgbImage or is not the same
     * size as the background image set in the constructor.
     */
    public void push(Image imInput) throws Error {
        {
        if (!(imInput instanceof RgbImage)) 
            throw new Error(
                			Error.PACKAGE.ALGORITHM,
                			ErrorCodes.IMAGE_NOT_RGBIMAGE,
                			imInput.toString(),
                			null,
                			null);
        }
        if (imInput.getWidth() != this.rgbBack.getWidth() ||
        	imInput.getHeight() != this.rgbBack.getHeight()) {
        	throw new Error(
        				Error.PACKAGE.ALGORITHM,
        				ErrorCodes.IMAGE_SIZES_DIFFER,
        				imInput.toString(),
        				this.rgbBack.toString(),
        				null);
        
        }

        Integer[] wInput = ((RgbImage)imInput).getData();
        Integer[] wBack = this.rgbBack.getData();
        Gray8Image grayOut = new Gray8Image(
                this.rgbBack.getWidth(), 
                this.rgbBack.getHeight());        
        Byte[] bGray = grayOut.getData();
        for (int i=0; i