/*
* PsfGray8.java
*
* Created on November 3, 2007, 2:58 PM
*
* 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 <http://www.gnu.org/licenses/>.
*
*/
package jjil.algorithm;
import jjil.core.Gray8Image;
/**
* Provides point spread functions for use in inverse filtering.
* @author webb
*/
public class PsfGray8 {
/**
* Computes a horizontal bar point spread function, with a given width.
* This corresponds to a horizontal blur. The output image is scaled so the sum
* of all values is 256.
* @param nImageWidth The image width of the image to create. The image is always square so this is
* also the height.
* @param nBarHalfWidth The width of the bar, divided by 2 and rounded down. The actual width is
* twice this width plus 1, centered on the center of the image.
* @return A Gray8Image that can be passed to InverseFilter to remove horizontal blur.
*/
public static Gray8Image horizBar(int nImageWidth, int nBarHalfWidth) {
Gray8Image imResult = new Gray8Image(nImageWidth, nImageWidth, Byte.MIN_VALUE);
byte bData[] = imResult.getData();
int nC = nImageWidth / 2;
int nArea = 2 * nBarHalfWidth + 1;
int nRow = nC * nImageWidth;
for (int j = -nBarHalfWidth; j <= nBarHalfWidth; j++) {
bData[nRow + nC + j] = (byte) (Byte.MAX_VALUE / nArea);
}
return imResult;
}
/**
* Computes a disk-shaped point spread function that can be used to do deblurring
* for circular blur. The output image is scaled so the sum of the values is 256.
* @param nImageWidth The output image width. The image is always square so this is also the
* height.
* @param nRadius The radius of the disk.
* @return A Gray8Image that can be passed to InverseFilter to remove circular blur,
* for example that due to defocus.
*/
public static Gray8Image disk(int nImageWidth, int nRadius) {
Gray8Image imResult = new Gray8Image(nImageWidth, nImageWidth, Byte.MIN_VALUE);
byte bData[] = imResult.getData();
int nC = nImageWidth / 2;
int nRadiusSq = nRadius * nRadius;
int nArea = 0;
// compute area of the disk. The rounding is tricky so I decided
// to just count.
for (int i = -nRadius; i <= nRadius; i++) {
for (int j = -nRadius; j <= nRadius; j++) {
if (i*i + j*j <= nRadiusSq) {
nArea ++;
}
}
}
for (int i = -nRadius; i <= nRadius; i++) {
int nRow = (nC + i) * nImageWidth;
for (int j = -nRadius; j <= nRadius; j++) {
if (i*i + j*j <= nRadiusSq) {
bData[nRow + nC + j] = (byte) (Byte.MAX_VALUE / nArea);
}
}
}
return imResult;
}
}