/*
* 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 <http://www.gnu.org/licenses/>.
*
*/
package jjil.algorithm;
import jjil.core.Error;
import jjil.core.Gray8Image;
import jjil.core.Image;
import jjil.core.PipelineStage;
import jjil.core.RgbImage;
import jjil.core.RgbVal;
/**
* Thresholds an RgbImage based on a given RGB value and another
* RGB value that represents the masimum RGB distance from the
* first value that a pixel can lie in to be considered within
* the threshold.
* The computation is analogous to a vector distance from a given
* point. It can be described as </br>
* (rgb - rgbTarget) · rgbVec < threshold
* @author webb
*/
public class RgbVecThresh extends PipelineStage {
private int nR, nG, nB;
private int nRVec, nGVec, nBVec;
private int nThresh;
private boolean bWithin;
/**
* Initialize class to filter based on given target rgb value
* and vector distance from the target value measured along
* a particular vector. The bWithin parameter allows the
* threshold test to be reversed -- bWithin = false causes
* true (Byte.MAX_VALUE) to be output for rgb values > than
* the test.
* @param rgbTarget target RGB value
* @param rgbVec direction and distance of test
* @param nThresh threshold to compare with
* @param bWithin if true result is true if < test; if false,
* result is true if > than the test.
*/
public RgbVecThresh(int rgbTarget, int rgbVec, int nThresh, boolean bWithin) {
this.nR = RgbVal.getR(rgbTarget) - Byte.MIN_VALUE;
this.nG = RgbVal.getG(rgbTarget) - Byte.MIN_VALUE;
this.nB = RgbVal.getB(rgbTarget) - Byte.MIN_VALUE;
this.nRVec = RgbVal.getR(rgbVec);
this.nGVec = RgbVal.getG(rgbVec);
this.nBVec = RgbVal.getB(rgbVec);
this.nThresh = nThresh;
this.bWithin = bWithin;
}
/**
* Perform thresholding operation. Output is a gray image.
* @param imageInput input RgbImage to be thresholded.
* @throws jjil.core.Error if input is not an RgbImage.
*/
public void push(Image imageInput) throws Error {
if (!(imageInput instanceof RgbImage)) {
throw new Error(
Error.PACKAGE.ALGORITHM,
ErrorCodes.IMAGE_NOT_RGBIMAGE,
imageInput.toString(),
null,
null);
}
RgbImage rgb = (RgbImage) imageInput;
int[] nData = rgb.getData();
Gray8Image imageResult = new Gray8Image(rgb.getWidth(), rgb.getHeight());
byte[] bData = imageResult.getData();
for (int i=0; i<rgb.getWidth()*rgb.getHeight(); i++) {
int nRCurr = RgbVal.getR(nData[i]) - Byte.MIN_VALUE;
int nGCurr = RgbVal.getG(nData[i]) - Byte.MIN_VALUE;
int nBCurr = RgbVal.getB(nData[i]) - Byte.MIN_VALUE;
int nRDiff = nRCurr - this.nR;
int nGDiff = nGCurr - this.nG;
int nBDiff = nBCurr - this.nB;
int nDot = Math.abs(nRDiff * this.nRVec +
nGDiff * this.nGVec +
nBDiff * this.nBVec);
bData[i] = ((nDot < this.nThresh) == this.bWithin)
? Byte.MAX_VALUE : Byte.MIN_VALUE;
}
super.setOutput(imageResult);
}
}