/* Given a sample from the image gradient, place it in the index array.
*/
void AddSample(
float index[IndexSize][IndexSize][OriSize], keypoint& key,
const flimage& grad, const flimage& orim,
float r, float c, float rpos, float cpos, float rx, float cx,siftPar &par)
{
/* Clip at image boundaries. */
if (r < 0 || r >= grad.nheight() || c < 0 || c >= grad.nwidth())
return;
/* Compute Gaussian weight for sample, as function of radial distance
from center. Sigma is relative to half-width of index. */
float sigma = par.IndexSigma * 0.5 * IndexSize,
weight = exp(- (rpos * rpos + cpos * cpos) / (2.0 * sigma * sigma)),
// mag = weight * grad(c,r);
mag = weight * grad((int)c,(int)r); // Guoshen Yu, explicitely cast to int to avoid warning
/* Subtract keypoint orientation to give ori relative to keypoint. */
// float ori = orim(c,r) - key.angle;
float ori = orim((int)c,(int)r) - key.angle; // Guoshen Yu, explicitely cast to int to avoid warning
/* Put orientation in range [0, 2*PI]. If sign of gradient is to
be ignored, then put in range [0, PI]. */
if (par.IgnoreGradSign) {
while (ori > PI ) ori -= PI;
while (ori < 0.0) ori += PI;
} else {
while (ori > 2.0*PI) ori -= 2.0*PI;
while (ori < 0.0 ) ori += 2.0*PI;
}
PlaceInIndex(index, mag, ori, rx, cx,par);
}
/* Given a sample from the image gradient, place it in the index array.
*/
void AddSample(
float index[IndexSize][IndexSize][OriSize], keypoint& key,
const flimage& grad,
int r, int c, float rpos, float cpos, float rx, float cx,siftPar &par)
{
/* Clip at image boundaries. */
if (r < 0 || r >= grad.h || c < 0 || c >= grad.w)
return;
const float* g = grad.pixel(c,r);
/* Compute Gaussian weight for sample, as function of radial distance
from center. Sigma is relative to half-width of index. */
float sigma = par.IndexSigma * 0.5f * IndexSize,
weight = exp(- (rpos * rpos + cpos * cpos) / (2.0f * sigma * sigma)),
mag = weight * g[0];
/* Subtract keypoint orientation to give ori relative to keypoint. */
float ori = g[1] - key.angle;
/* Put orientation in range [0, 2*PI]. If sign of gradient is to
be ignored, then put in range [0, PI]. */
if (par.IgnoreGradSign) {
while (ori > M_PI ) ori -= M_PI;
while (ori < 0.0f) ori += M_PI;
} else {
while (ori > 2.0f*M_PI) ori -= 2.0f*M_PI;
while (ori < 0.0f ) ori += 2.0f*M_PI;
}
PlaceInIndex(index, mag, ori, rx, cx,par);
}
/* Given a sample from the image gradient, place it in the index array.
*/
void AddSample(float index[IndexSize][IndexSize][OriSize], KKeypoint k,
Image grad, Image orim, int r, int c, float rpos, float cpos,
float rx, float cx)
{
float mag, ori, sigma, weight;
/* Clip at image boundaries. */
if (r < 0 || r >= grad->rows || c < 0 || c >= grad->cols)
return;
/* Compute Gaussian weight for sample, as function of radial distance
from center. Sigma is relative to half-width of index.
*/
sigma = IndexSigma * 0.5 * IndexSize;
weight = exp(- (rpos * rpos + cpos * cpos) / (2.0 * sigma * sigma));
mag = weight * grad->pixels[r][c];
/* Subtract keypoint orientation to give ori relative to keypoint. */
ori = orim->pixels[r][c] - k->ori;
/* Put orientation in range [0, 2*PII]. If sign of gradient is to
be ignored, then put in range [0, PII].
*/
if (IgnoreGradSign) {
while (ori > PII)
ori -= PII;
while (ori < 0.0)
ori += PII;
} else {
while (ori > 2*PII)
ori -= 2*PII;
while (ori < 0.0)
ori += 2*PII;
}
PlaceInIndex(index, mag, ori, rx, cx);
}
