boofcv.alg.flow.HornSchunck_U8 Maven / Gradle / Ivy
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BoofCV is an open source Java library for real-time computer vision and robotics applications.
/*
* Copyright (c) 2011-2016, Peter Abeles. All Rights Reserved.
*
* This file is part of BoofCV (http://boofcv.org).
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package boofcv.alg.flow;
import boofcv.struct.flow.ImageFlow;
import boofcv.struct.image.GrayF32;
import boofcv.struct.image.GrayS16;
import boofcv.struct.image.GrayU8;
import boofcv.struct.image.ImageType;
/**
* Implementation of {@link HornSchunck} for {@link GrayF32}.
*
* @author Peter Abeles
*/
public class HornSchunck_U8 extends HornSchunck {
public HornSchunck_U8(float alpha, int numIterations) {
super(alpha,numIterations, ImageType.single(GrayS16.class));
}
@Override
protected void computeDerivX(GrayU8 image1, GrayU8 image2, GrayS16 derivX) {
int w = image1.width-1;
int h = image1.height-1;
for( int y = 0; y < h; y++ ) {
int index1 = image1.startIndex + y*image1.stride;
int index2 = image2.startIndex + y*image2.stride;
int indexX = derivX.startIndex + y*derivX.stride;
for( int x = 0; x < w; x++ , index1++ , index2++ , indexX++ ) {
int d0 = (image1.data[index1+1]&0xFF) - (image1.data[index1]&0xFF);
int d2 = (image2.data[index2+1]&0xFF) - (image2.data[index2]&0xFF);
int d1 = (image1.data[index1+1+image1.stride]&0xFF) - (image1.data[index1+image1.stride]&0xFF);
int d3 = (image2.data[index2+1+image2.stride]&0xFF) - (image2.data[index2+image2.stride]&0xFF);
derivX.data[indexX] = (short)((d0 + d1 + d2 + d3)/4);
}
}
for( int y = 0; y < image1.height; y++ ) {
derivX.unsafe_set(w,y, 0);
}
for( int x = 0; x < w; x++ ) {
int d0 = image1.unsafe_get(x+1,h) - image1.unsafe_get(x,h);
int d1 = image2.unsafe_get(x+1,h) - image2.unsafe_get(x,h);
derivX.unsafe_set(x,h, (d0+d1)/2);
}
}
@Override
protected void computeDerivY(GrayU8 image1, GrayU8 image2, GrayS16 derivY) {
int w = image1.width-1;
int h = image1.height-1;
for( int y = 0; y < h; y++ ) {
int index1 = image1.startIndex + y*image1.stride;
int index2 = image2.startIndex + y*image2.stride;
int indexY = derivY.startIndex + y*derivY.stride;
for( int x = 0; x < w; x++ , index1++ , index2++ , indexY++ ) {
int d0 = (image1.data[index1+image1.stride]&0xFF) - (image1.data[index1]&0xFF);
int d2 = (image2.data[index2+image2.stride]&0xFF) - (image2.data[index2]&0xFF);
int d1 = (image1.data[index1+1+image1.stride]&0xFF) - (image1.data[index1+1]&0xFF);
int d3 = (image2.data[index2+1+image2.stride]&0xFF) - (image2.data[index2+1]&0xFF);
derivY.data[indexY] = (short)((d0 + d1 + d2 + d3)/4);
}
}
for( int y = 0; y < h; y++ ) {
int d0 = image1.unsafe_get(w, y + 1) - image1.unsafe_get(w,y);
int d1 = image2.unsafe_get(w, y + 1) - image2.unsafe_get(w,y);
derivY.unsafe_set(w,y, (d0+d1)/2);
}
for( int x = 0; x < w; x++ ) {
derivY.unsafe_set(x, h, 0);
}
}
@Override
protected void computeDerivT(GrayU8 image1, GrayU8 image2, GrayS16 difference) {
int w = image1.width-1;
int h = image1.height-1;
for( int y = 0; y < h; y++ ) {
int index1 = image1.startIndex + y*image1.stride;
int index2 = image2.startIndex + y*image2.stride;
int indexDiff = difference.startIndex + y*difference.stride;
for( int x = 0; x < w; x++ , index1++ , index2++ , indexDiff++ ) {
int d0 = (image2.data[index2]&0xFF) - (image1.data[index1]&0xFF); // (x ,y )
int d1 = (image2.data[index2+1]&0xFF) - (image1.data[index1+1]&0xFF); // (x+1,y )
int d2 = (image2.data[index2+image2.stride]&0xFF) - (image1.data[index1+image1.stride]&0xFF); // (x ,y+1)
int d3 = (image2.data[index2+1+image2.stride]&0xFF) - (image1.data[index1+1+image1.stride]&0xFF);// (x+1,y+1)
difference.data[indexDiff] = (short)((d0 + d1 + d2 + d3)/4);
}
}
for( int y = 0; y < image1.height; y++ ) {
borderDerivT(image1, image2, difference, w, y);
}
for( int x = 0; x < w; x++ ) {
borderDerivT(image1, image2, difference, x, h);
}
}
protected static void borderDerivT(GrayU8 imageA , GrayU8 imageB ,
GrayS16 difference, int x, int y) {
float d0 = getBorderT(imageA, imageB, x , y );
float d1 = getBorderT(imageA, imageB, x + 1, y );
float d2 = getBorderT(imageA, imageB, x , y + 1);
float d3 = getBorderT(imageA, imageB, x + 1, y + 1);
difference.unsafe_set(x,y, (short)((d0+d1+d2+d3)/4));
}
protected static float getBorderT(GrayU8 imageA, GrayU8 imageB, int x, int y) {
if( x < 0 ) x = 0;
else if( x >= imageA.width ) x = imageA.width-1;
if( y < 0 ) y = 0;
else if( y >= imageA.height ) y = imageA.height-1;
return imageB.unsafe_get(x,y) - imageA.unsafe_get(x,y);
}
@Override
protected void findFlow(GrayS16 derivX , GrayS16 derivY ,
GrayS16 derivT , ImageFlow output) {
int N = output.width*output.height;
for( int iter = 0; iter < numIterations; iter++ ) {
borderAverageFlow(output,averageFlow);
innerAverageFlow(output,averageFlow);
for( int i = 0; i < N; i++ ) {
float dx = derivX.data[i];
float dy = derivY.data[i];
float dt = derivT.data[i];
ImageFlow.D aveFlow = averageFlow.data[i];
float u = aveFlow.x;
float v = aveFlow.y;
ImageFlow.D flow = output.data[i];
float r = (dx*u + dy*v + dt)/(alpha2 + dx*dx + dy*dy);
flow.x = u - dx*r;
flow.y = v - dy*r;
}
}
}
}