Changeset 2619 for libpipi/trunk/pipi/filter/blur.c

Timestamp:

08/01/08 00:02:30 (5 years ago)

Author:

sam

Message:

• filter/blur.c: avoid annoying side effects with very small or negative blur radii.

File:

• libpipi/trunk/pipi/filter/blur.c (modified) (4 diffs)

libpipi/trunk/pipi/filter/blur.c

@@ -28 +28 @@
 #include "pipi_internals.h"
 
+/* Any standard deviation below this value will be rounded up, in order
+ * to avoid ridiculously low values. exp(-1/(2*0.2*0.2)) is < 10^-5 so
+ * there is little chance that any value below 0.2 will be useful. */
+#define BLUR_EPSILON 0.2
+
 pipi_image_t *pipi_gaussian_blur(pipi_image_t *src, float radius)
 {
@@ -43 +48 @@
     int x, y, i, w, h, kr, kw;
 
+    if(rx < BLUR_EPSILON) rx = BLUR_EPSILON;
+    if(ry < BLUR_EPSILON) ry = BLUR_EPSILON;
+
     w = src->w;
     h = src->h;
@@ -55 +63 @@
     buffer = malloc(w * h * 4 * sizeof(double));
 
-    kr = (int)(3. * rx + 0.99999);
+    kr = (int)(3. * rx + 1.99999);
     kw = 2 * kr + 1;
     K = -1. / (2. * rx * rx);
@@ -92 +100 @@
     free(kernel);
 
-    kr = (int)(3. * ry + 0.99999);
+    kr = (int)(3. * ry + 1.99999);
     kw = 2 * kr + 1;
     K = -1. / (2. * ry * ry);