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Bilinear interpolation for resampling

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This commit is contained in:
Simon Robertshaw 2011-06-03 23:36:26 +01:00
parent 417a57b57a
commit 45e91c15b2
1 changed files with 28 additions and 5 deletions
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23
src/graphics.c
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@ -147,11 +147,34 @@ pixel *resample_img(pixel *src, int sw, int sh, int rw, int rh)
pixel *q;
q = malloc(rw*rh*PIXELSIZE);
//TODO: Actual resampling, this is just cheap nearest pixel crap
if(rw > sw && rh > sh){
float fx, fy, fyc, fxc, intp;
pixel tr, tl, br, bl;
//Bilinear interpolation for upscaling
for (y=0; y<rh; y++)
for (x=0; x<rw; x++)
{
fx = ((float)x)*((float)sw)/((float)rw);
fy = ((float)y)*((float)sh)/((float)rh);
fxc = modf(fx, &intp);
fyc = modf(fy, &intp);
tr = src[sw*(int)floor(fy)+(int)ceil(fx)];
tl = src[sw*(int)floor(fy)+(int)floor(fx)];
br = src[sw*(int)ceil(fy)+(int)ceil(fx)];
bl = src[sw*(int)ceil(fy)+(int)floor(fx)];
q[rw*y+x] = PIXRGB(
(int)(((((float)PIXR(tl))*(1.0f-fxc))+(((float)PIXR(tr))*(fxc)))*(1.0f-fyc) + ((((float)PIXR(bl))*(1.0f-fxc))+(((float)PIXR(br))*(fxc)))*(fyc)),
(int)(((((float)PIXG(tl))*(1.0f-fxc))+(((float)PIXG(tr))*(fxc)))*(1.0f-fyc) + ((((float)PIXG(bl))*(1.0f-fxc))+(((float)PIXG(br))*(fxc)))*(fyc)),
(int)(((((float)PIXB(tl))*(1.0f-fxc))+(((float)PIXB(tr))*(fxc)))*(1.0f-fyc) + ((((float)PIXB(bl))*(1.0f-fxc))+(((float)PIXB(br))*(fxc)))*(fyc))
);
}
} else {
for (y=0; y<rh; y++)
for (x=0; x<rw; x++)
{
q[rw*y+x] = src[sw*(y*sh/rh)+(x*sw/rw)];
}
}
//*qw = w;
//*qh = h;
return q;