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#define IMAGER_NO_CONTEXT
#include "imager.h"
#include "imageri.h"
/*
General convolution for 2d decoupled filters
end effects are acounted for by increasing
scaling the result with the sum of used coefficients
coeff: (double array) coefficients for filter
len: length of filter.. number of coefficients
note that this has to be an odd number
(since the filter is even);
*/
int
i_conv(i_img *im, const double *coeff,int len) {
i_img_dim xo, yo; /* output pixel co-ordinate */
int c, ch, center;
double pc;
double res[MAXCHANNELS];
i_img *timg;
dIMCTXim(im);
im_log((aIMCTX,1,"i_conv(im %p, coeff %p, len %d)\n",im,coeff,len));
im_clear_error(aIMCTX);
if (len < 1) {
im_push_error(aIMCTX, 0, "there must be at least one coefficient");
return 0;
}
center=(len-1)/2;
pc = 0;
for (c = 0; c < len; ++c)
pc += coeff[c];
if (pc == 0) {
i_push_error(0, "sum of coefficients is zero");
return 0;
}
timg = i_sametype(im, im->xsize, im->ysize);
#code im->bits <= 8
IM_COLOR rcolor;
/* don't move the calculation of pc up here, it depends on which pixels
are readable */
for(yo = 0; yo < im->ysize; yo++) {
for(xo = 0; xo < im->xsize; xo++) {
for(ch = 0;ch < im->channels; ch++)
res[ch] = 0;
for(c = 0;c < len; c++) {
i_img_dim xi = xo + c - center;
if (xi < 0)
xi = 0;
else if (xi >= im->xsize)
xi = im->xsize - 1;
if (IM_GPIX(im, xi, yo, &rcolor)!=-1) {
for(ch = 0; ch < im->channels; ch++)
res[ch] += (rcolor.channel[ch]) *coeff[c];
}
}
im_assert(pc != 0);
for(ch = 0; ch < im->channels; ch++) {
double temp = res[ch] / pc;
rcolor.channel[ch] =
temp < 0 ? 0 : temp > IM_SAMPLE_MAX ? IM_SAMPLE_MAX : (IM_SAMPLE_T)temp;
}
IM_PPIX(timg, xo, yo, &rcolor);
}
}
for(xo = 0; xo < im->xsize; xo++) {
for(yo = 0;yo < im->ysize; yo++) {
for(ch = 0; ch < im->channels; ch++)
res[ch] = 0;
for(c = 0; c < len; c++) {
i_img_dim yi = yo + c - center;
if (yi < 0)
yi = 0;
else if (yi >= im->ysize)
yi = im->ysize - 1;
if (IM_GPIX(timg, xo, yi, &rcolor) != -1) {
for(ch = 0;ch < im->channels; ch++)
res[ch] += (rcolor.channel[ch]) * coeff[c];
}
}
im_assert(pc != 0);
for(ch = 0;ch < im->channels; ch++) {
double temp = res[ch] / pc;
rcolor.channel[ch] =
temp < 0 ? 0 : temp > IM_SAMPLE_MAX ? IM_SAMPLE_MAX : (IM_SAMPLE_T)temp;
}
IM_PPIX(im, xo, yo,&rcolor);
}
}
#/code
i_img_destroy(timg);
return 1;
}
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