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/*
 * Gray8CannyVert.java
 *
 * Created on August 27, 2006, 4:32, PM
 *
 * To change this templatef, 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.Gray8Image;
import com.github.ojil.core.Image;
import com.github.ojil.core.ImageError;
import com.github.ojil.core.PipelineStage;

/**
 * Computes the vertical Canny operator for an input gray image. The sigma value
 * for the operator is set in the constructor or setSigma. All calculations are
 * done in integer (per CLDC 1.0) and the sigma value is specified as multiplied
 * by 10.0. The minimum value for the unmultiplied sigma is 0.1; the maximum
 * value is about 10.0. Larger sigma values give an operator which is less
 * sensitive to high frequencies and more sensitive to low frequencies.
 * 

* * @author webb */ public class Gray8CannyVert extends PipelineStage { /** * cSigma is the sigma value we'll be using. It has been multiplied by 10.0 * and converted to integer because CLDC 1.0 doesn't allow floating point. * The minimum legal value for cSigma is 1; the maximum is given by the * length of nCoeff below. */ private int cSigma; /** * nCoeff row i is the precomputed Canny coefficients for sigma = i/10.0. * They have been scaled by 256 and converted to integer because CLDC 1.0 * doesn't allow floating point. The coefficients have been scaled and * normalized so the sum is 0 and the sum of the absolute values is 256 * (counting both sides of the Canny operator -- the operator is symmetric * so we just give one side below.) The number of coefficients was * determined by generating them out to the point at which the unscaled * coefficient was less than a threshold, here 0.05. */ private final Integer[][] nCoeff = {// @formatter:off {0}, {-127, 21, 21, 21}, {-127, 21, 21, 21}, {-127, 25, 19, 19}, {-128, 42, 10, 10}, {-127, 56, 3, 3}, {-128, 57, 5}, {-128, 48, 15}, {-128, 32, 29, 1}, {-128, 16, 42, 5}, {-128, 0, 51, 11}, {-104, -11, 45, 16, 1}, {-89, -19, 39, 20, 3}, {-79, -24, 33, 24, 5}, {-72, -27, 27, 26, 8, 1}, {-67, -30, 21, 27, 11, 2}, {-63, -32, 16, 27, 14, 4}, {-61, -33, 12, 27, 17, 6}, {-58, -34, 8, 26, 20, 8}, {-56, -35, 4, 25, 22, 11}, {-55, -36, 0, 22, 22, 12, 4, 1}, {-51, -35, -2, 19, 22, 14, 6, 2}, {-48, -34, -5, 16, 21, 15, 7, 2}, {-45, -33, -7, 13, 20, 16, 9, 3}, {-43, -32, -9, 11, 19, 17, 10, 5}, {-41, -32, -10, 9, 18, 17, 11, 6}, {-40, -31, -11, 7, 17, 18, 13, 7}, {-39, -31, -12, 5, 16, 18, 14, 8}, {-38, -31, -13, 4, 15, 18, 15, 10}, {-37, -30, -14, 2, 14, 18, 16, 11}, {-36, -30, -15, 1, 13, 18, 17, 12}, {-34, -29, -16, -1, 10, 15, 15, 11, 7, 4}, {-33, -28, -16, -2, 9, 14, 15, 12, 8, 4}, {-32, -27, -16, -3, 7, 13, 14, 12, 8, 5}, {-31, -27, -16, -4, 6, 13, 14, 13, 9, 6}, {-30, -26, -17, -4, 5, 12, 14, 13, 10, 7}, {-29, -26, -17, -5, 4, 11, 14, 13, 11, 7}, {-29, -25, -17, -6, 3, 11, 14, 14, 11, 8}, {-28, -25, -17, -6, 3, 10, 14, 14, 12, 9}, {-27, -25, -17, -7, 2, 9, 13, 14, 13, 10}, {-27, -24, -17, -7, 1, 9, 13, 14, 13, 11}, {-26, -23, -17, -9, 0, 6, 11, 12, 11, 9, 7, 5}, {-25, -23, -17, -9, 0, 5, 10, 12, 11, 10, 7, 5}, {-25, -22, -17, -9, -1, 5, 9, 11, 11, 10, 8, 6}, {-24, -22, -17, -9, -2, 4, 9, 11, 11, 10, 8, 6}, {-23, -22, -17, -10, -2, 4, 8, 11, 12, 11, 9, 7}, {-23, -21, -17, -10, -3, 3, 8, 11, 12, 11, 9, 7}, {-23, -21, -16, -10, -3, 3, 7, 10, 12, 11, 10, 8}, {-22, -21, -16, -10, -3, 2, 7, 10, 12, 11, 10, 8}, {-22, -20, -16, -10, -4, 2, 7, 10, 12, 12, 10, 9}, {-22, -20, -16, -11, -4, 1, 6, 10, 11, 12, 11, 9}, {-21, -19, -16, -11, -5, 0, 4, 8, 9, 10, 9, 8, 6, 5}, {-20, -19, -16, -11, -5, 0, 4, 7, 9, 10, 9, 8, 7, 5}, {-20, -19, -16, -11, -6, 0, 3, 7, 9, 10, 10, 8, 7, 6}, {-20, -19, -16, -11, -6, -1, 3, 7, 9, 10, 10, 9, 7, 6}, {-19, -18, -15, -11, -6, -1, 3, 6, 9, 10, 10, 9, 8, 6}, {-19, -18, -15, -11, -6, -1, 2, 6, 8, 10, 10, 9, 8, 7}, {-19, -18, -15, -11, -6, -1, 2, 6, 8, 10, 10, 9, 8, 7}, {-18, -18, -15, -11, -7, -2, 2, 5, 8, 9, 10, 10, 9, 7}, {-18, -17, -15, -11, -7, -2, 1, 5, 8, 9, 10, 10, 9, 8}, {-18, -17, -15, -11, -7, -2, 1, 5, 8, 9, 10, 10, 9, 8}, {-17, -17, -14, -11, -7, -3, 0, 3, 6, 8, 8, 8, 8, 7, 6, 5}, {-17, -16, -14, -11, -7, -3, 0, 3, 6, 7, 8, 8, 8, 7, 6, 5}, {-17, -16, -14, -11, -8, -4, 0, 3, 5, 7, 8, 9, 8, 7, 6, 5}, {-17, -16, -14, -11, -8, -4, 0, 2, 5, 7, 8, 9, 8, 8, 7, 6}, {-16, -16, -14, -11, -8, -4, 0, 2, 5, 7, 8, 9, 8, 8, 7, 6}, {-16, -16, -14, -11, -8, -4, 0, 2, 5, 7, 8, 9, 8, 8, 7, 6}, {-16, -15, -14, -11, -8, -4, -1, 2, 4, 6, 8, 8, 9, 8, 7, 6}, {-16, -15, -14, -11, -8, -4, -1, 1, 4, 6, 8, 8, 9, 8, 8, 7}, {-16, -15, -13, -11, -8, -4, -1, 1, 4, 6, 8, 8, 9, 8, 8, 7}, {-15, -15, -13, -11, -8, -5, -1, 1, 4, 6, 8, 8, 9, 9, 8, 7}, {-15, -14, -13, -11, -8, -5, -2, 0, 3, 5, 6, 7, 7, 7, 7, 6, 5, 5}, {-15, -14, -13, -11, -8, -5, -2, 0, 2, 4, 6, 7, 7, 7, 7, 6, 6, 5}, {-15, -14, -13, -11, -8, -5, -2, 0, 2, 4, 6, 7, 7, 7, 7, 7, 6, 5}, {-14, -14, -13, -11, -8, -5, -2, 0, 2, 4, 6, 7, 7, 8, 7, 7, 6, 5}, {-14, -14, -13, -11, -8, -5, -3, 0, 2, 4, 6, 7, 7, 8, 7, 7, 6, 6}, {-14, -14, -12, -11, -8, -6, -3, 0, 2, 4, 5, 7, 7, 8, 7, 7, 6, 6}, {-14, -14, -12, -11, -8, -6, -3, 0, 1, 4, 5, 7, 7, 8, 8, 7, 7, 6}, {-14, -13, -12, -11, -8, -6, -3, 0, 1, 3, 5, 6, 7, 8, 8, 7, 7, 6}, {-14, -13, -12, -10, -8, -6, -3, 0, 1, 3, 5, 6, 7, 8, 8, 7, 7, 6}, {-13, -13, -12, -10, -8, -6, -3, -1, 1, 3, 5, 6, 7, 8, 8, 8, 7, 7}, {-13, -13, -12, -10, -8, -6, -4, -1, 0, 2, 4, 5, 6, 6, 7, 7, 6, 6, 5, 4}, {-13, -13, -12, -10, -8, -6, -4, -1, 0, 2, 4, 5, 6, 6, 7, 7, 6, 6, 5, 5}, {-13, -12, -12, -10, -8, -6, -4, -1, 0, 2, 3, 5, 6, 6, 7, 7, 6, 6, 5, 5}, {-13, -12, -11, -10, -8, -6, -4, -2, 0, 2, 3, 5, 6, 6, 7, 7, 6, 6, 6, 5}, {-13, -12, -11, -10, -8, -6, -4, -2, 0, 1, 3, 5, 6, 6, 7, 7, 7, 6, 6, 5}, {-12, -12, -11, -10, -8, -6, -4, -2, 0, 1, 3, 4, 6, 6, 7, 7, 7, 6, 6, 5}, {-12, -12, -11, -10, -8, -6, -4, -2, 0, 1, 3, 4, 5, 6, 7, 7, 7, 6, 6, 5}, {-12, -12, -11, -10, -8, -6, -4, -2, 0, 1, 3, 4, 5, 6, 7, 7, 7, 7, 6, 6}, {-12, -12, -11, -10, -8, -6, -4, -2, 0, 1, 3, 4, 5, 6, 7, 7, 7, 7, 6, 6}, {-12, -12, -11, -10, -8, -6, -4, -2, 0, 1, 3, 4, 5, 6, 7, 7, 7, 7, 6, 6}, {-12, -11, -11, -10, -8, -6, -5, -3, -1, 0, 2, 3, 4, 5, 6, 6, 6, 6, 6, 5, 5, 4}, {-11, -11, -11, -10, -8, -6, -5, -3, -1, 0, 2, 3, 4, 5, 6, 6, 6, 6, 6, 5, 5, 4}, {-11, -11, -11, -9, -8, -6, -5, -3, -1, 0, 1, 3, 4, 5, 6, 6, 6, 6, 6, 5, 5, 4}, {-11, -11, -10, -9, -8, -6, -5, -3, -1, 0, 1, 3, 4, 5, 6, 6, 6, 6, 6, 6, 5, 5}, {-11, -11, -10, -9, -8, -7, -5, -3, -1, 0, 1, 3, 4, 5, 5, 6, 6, 6, 6, 6, 5, 5}, {-11, -11, -10, -9, -8, -7, -5, -3, -1, 0, 1, 3, 4, 5, 5, 6, 6, 6, 6, 6, 5, 5}, {-11, -11, -10, -9, -8, -7, -5, -3, -1, 0, 1, 2, 4, 5, 5, 6, 6, 6, 6, 6, 5, 5}, {-11, -11, -10, -9, -8, -7, -5, -3, -1, 0, 1, 2, 4, 5, 5, 6, 6, 6, 6, 6, 6, 5}, {-11, -11, -10, -9, -8, -7, -5, -3, -1, 0, 1, 2, 4, 5, 5, 6, 6, 6, 6, 6, 6, 5}, };// @formatter:on /** * Creates a new instance of Gray8CannyVert * * @param cSigma * the sigma value for the operator, which is the sigma in the * Gaussian distribution multipied by 10.0 and converted to * integer. * @throws ImageError * if cSigma is out of range. */ public Gray8CannyVert(final int cSigma) throws ImageError { setSigma(cSigma); } /** * Apply the Canny operator vertically to the input input image. The sigma * value for the operator is set in the class constructor. We handle the * borders of the image a little carefully to avoid creating spurious edges * at them. The image value at the border is reflected so that image(0,-1), * for example, is made equal to image(0,1). * * @param image * the input Gray8Image * @throws ImageError * if the input is not a Gray8Image. */ @Override public void push(final Image image) throws ImageError { if (!(image instanceof Gray8Image)) { throw new ImageError(ImageError.PACKAGE.ALGORITHM, AlgorithmErrorCodes.IMAGE_NOT_GRAY8IMAGE, image.toString(), null, null); } final Gray8Image input = (Gray8Image) image; final Gray8Image result = new Gray8Image<>(image.getWidth(), image.getHeight()); final Byte[] bIn = input.getData(); final Byte[] bResult = result.getData(); final Integer[] wCoeff = nCoeff[cSigma]; final int cWidth = input.getWidth(); for (int j = 0; j < cWidth; j++) { for (int i = 0; i < input.getHeight(); i++) { /* top side of Canny operator */ int wSum = 0; /* * Use Math.abs to mirror the index at the border */ for (int k = 1; k < wCoeff.length; k++) { wSum += wCoeff[k] * bIn[(Math.abs(i - k) * cWidth) + j]; } /* bottom side of Canny operator */ for (int k = 0; k < wCoeff.length; k++) { if ((i + k) < input.getHeight()) { wSum += wCoeff[k] * bIn[((i + k) * cWidth) + j]; } else { // reflect at border. j + k >= cWidth so // 2*cWidth - (j + k + 1) < cWidth final int cPos = (2 * input.getHeight()) - (i + k + 1); wSum += wCoeff[k] * bIn[(cPos * cWidth) + j]; } } /* * Canny coefficients are scaled so sum of absolute values is * 256. */ wSum = wSum >> 8; bResult[(i * cWidth) + j] = (byte) wSum; } } super.setOutput(result); } /** * Returns the current value of sigma. * * @return the sigma value */ public int getSigma() { return cSigma; } /** * sets a new value for sigma. Sigma controls the frequency of edges that * the operator responds to. A small sigma value gives higher frequency * edges, while a larger sigma gives lower frequency edges. * * @param cSigma * the new sigma value * @throws ImageError * if cSigma is out of range. */ public void setSigma(final int cSigma) throws ImageError { if ((cSigma <= 1) || (cSigma >= nCoeff.length)) { throw new ImageError(ImageError.PACKAGE.ALGORITHM, AlgorithmErrorCodes.PARAMETER_OUT_OF_RANGE, new Integer(cSigma).toString(), new Integer(1).toString(), new Integer(nCoeff.length).toString()); } this.cSigma = cSigma; } /** * returns a string describing this Canny operator. * * @return a string describing the Canny operator. */ @Override public String toString() { return super.toString() + " (" + cSigma + ")"; //$NON-NLS-1$ //$NON-NLS-2$ } }





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