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Precompute coefficients for all x

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This commit is contained in:
homm 2014-10-25 05:37:33 +04:00
parent 40f9f48680
commit b77521bd6c
1 changed files with 40 additions and 5 deletions
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45
libImaging/Antialias.c
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@ -88,8 +88,8 @@ ImagingStretchHorizaontal(Imaging imOut, Imaging imIn, int filter)
struct filter *filterp;
float support, scale, filterscale;
float center, ww, ss, xmin, xmax;
int xx, yy, x, b;
float *k;
int xx, yy, x, b, kmax;
float *k, *kk, *xbounds;
/* check modes */
if (!imOut || !imIn || strcmp(imIn->mode, imOut->mode) != 0)
@ -132,11 +132,45 @@ ImagingStretchHorizaontal(Imaging imOut, Imaging imIn, int filter)
support = support * filterscale;
/* maximum number of coofs */
kmax = (int) ceil(support) * 2 + 1;
/* coefficient buffer (with rounding safety margin) */
k = malloc(((int) support * 2 + 10) * sizeof(float));
if (!k)
kk = malloc(imOut->xsize * kmax * sizeof(float));
if ( ! kk)
return (Imaging) ImagingError_MemoryError();
xbounds = malloc(imOut->xsize * 3 * sizeof(float));
if ( ! xbounds) {
free(kk);
return (Imaging) ImagingError_MemoryError();
}
for (xx = 0; xx < imOut->xsize; xx++) {
k = &kk[xx * kmax];
center = (xx + 0.5) * scale;
ww = 0.0;
ss = 1.0 / filterscale;
xmin = floor(center - support);
if (xmin < 0.0)
xmin = 0.0;
xmax = ceil(center + support);
if (xmax > (float) imIn->xsize)
xmax = (float) imIn->xsize;
for (x = (int) xmin; x < (int) xmax; x++) {
float w = filterp->filter((x - center + 0.5) * ss) * ss;
k[x - (int) xmin] = w;
ww = ww + w;
}
if (ww == 0.0)
ww = 1.0;
else
ww = 1.0 / ww;
xbounds[xx * 3 + 0] = xmin;
xbounds[xx * 3 + 1] = xmax;
xbounds[xx * 3 + 2] = ww;
}
ImagingSectionEnter(&cookie);
/* horizontal stretch */
for (xx = 0; xx < imOut->xsize; xx++) {
@ -218,7 +252,8 @@ ImagingStretchHorizaontal(Imaging imOut, Imaging imIn, int filter)
}
ImagingSectionLeave(&cookie);
free(k);
free(kk);
free(xbounds);
return imOut;
}