/*
* 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 <http://www.gnu.org/licenses/>.
*
*/
package jjil.algorithm;
import jjil.core.Error;
import jjil.core.Gray8Image;
import jjil.core.Image;
import jjil.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.
* <p>
* @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 int[][] nCoeff = {
{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},
};
/**
* 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 jjil.core.Error if cSigma is out of range.
*/
public Gray8CannyVert(int cSigma) throws jjil.core.Error {
this.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 jjil.core.Error if the input is not a Gray8Image.
*/
public void push(Image image) throws jjil.core.Error {
if (!(image instanceof Gray8Image)) {
throw new Error(
Error.PACKAGE.ALGORITHM,
ErrorCodes.IMAGE_NOT_GRAY8IMAGE,
image.toString(),
null,
null);
}
Gray8Image input = (Gray8Image) image;
Gray8Image result = new Gray8Image(image.getWidth(), image.getHeight());
byte[] bIn = input.getData();
byte[] bResult = result.getData();
int[] wCoeff = this.nCoeff[this.cSigma];
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
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 this.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 jjil.core.Error if cSigma is out of range.
*/
public void setSigma(int cSigma) throws jjil.core.Error {
if (cSigma <= 1 || cSigma >= this.nCoeff.length) {
throw new Error(
Error.PACKAGE.ALGORITHM,
ErrorCodes.PARAMETER_OUT_OF_RANGE,
new Integer(cSigma).toString(),
new Integer(1).toString(),
new Integer(this.nCoeff.length).toString());
}
this.cSigma = cSigma;
}
/** returns a string describing this Canny operator.
*
* @return a string describing the Canny operator.
*/
public String toString() {
return super.toString() + " (" + this.cSigma + ")"; //$NON-NLS-1$ //$NON-NLS-2$
}
}