求解释这段模糊算法?

xieyangxuejun

由 xieyangxuejun 发布于 2017年03月30日

无人欣赏。

int *blur_ARGB_8888(int *pix, int w, int h, int radius) {
int wm = w - 1;
int hm = h - 1;
int wh = w * h;
int div = radius + radius + 1;
short *r = (short *) malloc(wh * sizeof(short));
short *g = (short *) malloc(wh * sizeof(short));
short *b = (short *) malloc(wh * sizeof(short));
int rsum, gsum, bsum, x, y, i, p, yp, yi, yw;
int *vmin = (int *) malloc(MAX(w, h) * sizeof(int));
int divsum = (div + 1) >> 1;
divsum *= divsum;
short *dv = (short *) malloc(256 * divsum * sizeof(short));
for (i = 0; i < 256 * divsum; i++) {
 dv[i] = (short) (i / divsum);
}
yw = yi = 0;
int(*stack)[3] = (int (*)[3]) malloc(div * 3 * sizeof(int));
int stackpointer;
int stackstart;
int *sir;
int rbs;
int r1 = radius + 1;
int routsum, goutsum, boutsum;
int rinsum, ginsum, binsum;
for (y = 0; y < h; y++) {
 rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
 for (i = -radius; i <= radius; i++) {
 p = pix[yi + (MIN(wm, MAX(i, 0)))];
 sir = stack[i + radius];
 sir[0] = (p & 0xff0000) >> 16;
 sir[1] = (p & 0x00ff00) >> 8;
 sir[2] = (p & 0x0000ff);
 rbs = r1 - ABS(i);
 rsum += sir[0] * rbs;
 gsum += sir[1] * rbs;
 bsum += sir[2] * rbs;
 if (i > 0) {
 rinsum += sir[0];
 ginsum += sir[1];
 binsum += sir[2];
 }
 else {
 routsum += sir[0];
 goutsum += sir[1];
 boutsum += sir[2];
 }
 }
 stackpointer = radius;
 for (x = 0; x < w; x++) {
 r[yi] = dv[rsum];
 g[yi] = dv[gsum];
 b[yi] = dv[bsum];
 rsum -= routsum;
 gsum -= goutsum;
 bsum -= boutsum;
 stackstart = stackpointer - radius + div;
 sir = stack[stackstart % div];
 routsum -= sir[0];
 goutsum -= sir[1];
 boutsum -= sir[2];
 if (y == 0) {
 vmin[x] = MIN(x + radius + 1, wm);
 }
 p = pix[yw + vmin[x]];
 sir[0] = (p & 0xff0000) >> 16;
 sir[1] = (p & 0x00ff00) >> 8;
 sir[2] = (p & 0x0000ff);
 rinsum += sir[0];
 ginsum += sir[1];
 binsum += sir[2];
 rsum += rinsum;
 gsum += ginsum;
 bsum += binsum;
 stackpointer = (stackpointer + 1) % div;
 sir = stack[(stackpointer) % div];
 routsum += sir[0];
 goutsum += sir[1];
 boutsum += sir[2];
 rinsum -= sir[0];
 ginsum -= sir[1];
 binsum -= sir[2];
 yi++;
 }
 yw += w;
}
for (x = 0; x < w; x++) {
 rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
 yp = -radius * w;
 for (i = -radius; i <= radius; i++) {
 yi = MAX(0, yp) + x;
 sir = stack[i + radius];
 sir[0] = r[yi];
 sir[1] = g[yi];
 sir[2] = b[yi];
 rbs = r1 - ABS(i);
 rsum += r[yi] * rbs;
 gsum += g[yi] * rbs;
 bsum += b[yi] * rbs;
 if (i > 0) {
 rinsum += sir[0];
 ginsum += sir[1];
 binsum += sir[2];
 }
 else {
 routsum += sir[0];
 goutsum += sir[1];
 boutsum += sir[2];
 }
 if (i < hm) {
 yp += w;
 }
 }
 yi = x;
 stackpointer = radius;
 for (y = 0; y < h; y++) {
 // Preserve alpha channel: ( 0xff000000 & pix[yi] )
 pix[yi] = (0xff000000 & pix[yi]) | (dv[rsum] << 16) | (dv[gsum] << 8) | dv[bsum];
 rsum -= routsum;
 gsum -= goutsum;
 bsum -= boutsum;
 stackstart = stackpointer - radius + div;
 sir = stack[stackstart % div];
 routsum -= sir[0];
 goutsum -= sir[1];
 boutsum -= sir[2];
 if (x == 0) {
 vmin[y] = MIN(y + r1, hm) * w;
 }
 p = x + vmin[y];
 sir[0] = r[p];
 sir[1] = g[p];
 sir[2] = b[p];
 rinsum += sir[0];
 ginsum += sir[1];
 binsum += sir[2];
 rsum += rinsum;
 gsum += ginsum;
 bsum += binsum;
 stackpointer = (stackpointer + 1) % div;
 sir = stack[stackpointer];
 routsum += sir[0];
 goutsum += sir[1];
 boutsum += sir[2];
 rinsum -= sir[0];
 ginsum -= sir[1];
 binsum -= sir[2];
 yi += w;
 }
}
free(r);
free(g);
free(b);
free(vmin);
free(dv);
free(stack);
return (pix);

}

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