private void constructHistograms(double c_x, double c_y, double scale, double orientation) {
double c = Math.cos(orientation);
double s = Math.sin(orientation);
int gridRadius = gridWidth / 2;
// This is the distance between samples
// The size is computed by finding the width of one block in the grid, then dividing by the
// number of samples along that side
double sampleUnit = (2.0 * scale * sigmaToRadius) / numSamples;
// how wide a grid cell is in pixels
double gridCellLength = numSamples * sampleUnit;
int gridCellLengthI = (int) (gridCellLength + 0.5); // round to int
// System.out.println("-----------------------------------------");
// System.out.println(" cell length "+gridCellLength);
// System.out.println(" sampleUnit "+sampleUnit);
int allSampleIndex = 0;
for (int gy = 0; gy < gridWidth; gy++) {
double gridY = (gy - gridRadius) * gridCellLength;
for (int gx = 0; gx < gridWidth; gx++) {
// top left coordinate of grid in pixels
double gridX = (gx - gridRadius) * gridCellLength;
// TODO Sample all pixels here
for (int sy = 0; sy < numSamples; sy++) {
double y = sy * sampleUnit + gridY;
for (int sx = 0; sx < numSamples; sx++, allSampleIndex++) {
// Sample point in pixels in grid coordinate system
double x = sx * sampleUnit + gridX;
// Rotate and translate into image pixel coordinates, then round
int px = (int) (x * c - y * s + c_x + 0.5);
int py = (int) (x * s + y * c + c_y + 0.5);
if (image.isInBounds(px, py)) {
double dx = derivX.unsafe_get(px, py);
double dy = derivY.unsafe_get(px, py);
// Gaussian weighting applied to whole sample area
double w = gridWeights[allSampleIndex];
// rotate derivative into grid coordinate system
double adjX = (dx * c + dy * s) * w;
double adjY = (-dx * s + dy * c) * w;
addToHistograms(
gx - gridRadius,
gy - gridRadius,
x / gridCellLength,
y / gridCellLength,
adjX,
adjY);
}
}
}
}
}
}
/** Sets a rectangle inside the image with the specified value. */
public static void fillRectangle(
ImageFloat32 img, float value, int x0, int y0, int width, int height) {
int x1 = x0 + width;
int y1 = y0 + height;
for (int y = y0; y < y1; y++) {
for (int x = x0; x < x1; x++) {
if (img.isInBounds(x, y)) img.set(x, y, value);
}
}
}
public void checkBorder(ImageFloat32 image, int c_x, int c_y, int w, int h) {
ImplDescribePointPixelRegion_F32 alg = new ImplDescribePointPixelRegion_F32(w, h);
TupleDesc_F32 desc = new TupleDesc_F32(alg.getDescriptorLength());
alg.setImage(image);
alg.process(c_x, c_y, desc);
int index = 0;
int y0 = c_y - h / 2;
int x0 = c_x - w / 2;
for (int y = y0; y < y0 + h; y++) {
for (int x = x0; x < x0 + w; x++, index++) {
if (image.isInBounds(x, y)) assertEquals(image.get(x, y), desc.value[index], 1e-4);
else assertEquals(0, desc.value[index], 1e-4);
}
}
}
