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Stairstepping for downscaling

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This commit is contained in:
Simon Robertshaw 2011-06-04 12:37:24 +01:00
parent b850abe347
commit 8a5e566b77
1 changed files with 45 additions and 13 deletions
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58
src/graphics.c
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@ -144,13 +144,12 @@ pixel *resample_img(pixel *src, int sw, int sh, int rw, int rh)
{
int y, x;
//int i,j,x,y,w,h,r,g,b,c;
pixel *q;
q = malloc(rw*rh*PIXELSIZE);
pixel *q = NULL;
//TODO: Actual resampling, this is just cheap nearest pixel crap
//if(rw > sw && rh > sh){
//if(1){
if(rw > sw && rh > sh){
float fx, fy, fyc, fxc, intp;
pixel tr, tl, br, bl;
q = malloc(rw*rh*PIXELSIZE);
//Bilinear interpolation for upscaling
for (y=0; y<rh; y++)
for (x=0; x<rw; x++)
@ -169,15 +168,48 @@ pixel *resample_img(pixel *src, int sw, int sh, int rw, int rh)
(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;
} else {
//Stairstepping
float fx, fy, fyc, fxc, intp;
pixel tr, tl, br, bl;
int rrw = rw, rrh = rh;
pixel * oq;
oq = malloc(sw*sh*PIXELSIZE);
memcpy(oq, src, sw*sh*PIXELSIZE);
rw = sw;
rh = sh;
while(rrw != rw && rrh != rh){
rw *= 0.7;
rh *= 0.7;
if(rw <= rrw || rh <= rrh){
rw = rrw;
rh = rrh;
}
q = malloc(rw*rh*PIXELSIZE);
//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 = oq[sw*(int)floor(fy)+(int)ceil(fx)];
tl = oq[sw*(int)floor(fy)+(int)floor(fx)];
br = oq[sw*(int)ceil(fy)+(int)ceil(fx)];
bl = oq[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))
);
}
free(oq);
oq = q;
sw = rw;
sh = rh;
}
}
return q;
}