Changeset 24481 for trunk/psLib/src/imageops/psImageBackground.c

Timestamp:

Jun 17, 2009, 8:46:53 PM (17 years ago)

Author:

eugene

Message:

min,max incorrectly calculated; for Nsubset > Npixels, loop directly over pixels

File:

• trunk/psLib/src/imageops/psImageBackground.c (modified) (1 diff)

trunk/psLib/src/imageops/psImageBackground.c

@@ -52 +52 @@
 
     // Minimum and maximum values
-    float min = values->data.F32[0];
-    float max = values->data.F32[0];
+    float min = +PS_MAX_F32;
+    float max = -PS_MAX_F32;
 
     // select a subset of the image pixels to measure the stats
     long n = 0;                         // Number of actual pixels in subset
-    for (long i = 0; i < Nsubset; i++) {
-        double frnd = psRandomUniform(rng);
-        int pixel = Npixels * frnd;
-        int ix = pixel % nx;
-        int iy = pixel / nx;
+    if (Nsubset >= Npixels) {
+        // if we have an image smaller than Nsubset, just loop over the image pixels
+        for (int iy = 0; iy < ny; iy++) {
+            for (int ix = 0; ix < nx; ix++) {
+                if (!isfinite(image->data.F32[iy][ix]) || (mask && mask->data.PS_TYPE_IMAGE_MASK_DATA[iy][ix] & maskValue)) {
+                    continue;
+                }
 
-        if (!isfinite(image->data.F32[iy][ix]) || (mask && mask->data.PS_TYPE_IMAGE_MASK_DATA[iy][ix] & maskValue)) {
-            continue;
-        }
+                float value = image->data.F32[iy][ix];
+                min = PS_MIN(value, min);
+                max = PS_MAX(value, max);
+                values->data.F32[n] = value;
+                n++;
+            }
+        }
+    } else {
+        for (long i = 0; i < Nsubset; i++) {
+            double frnd = psRandomUniform(rng);
+            int pixel = Npixels * frnd;
+            int ix = pixel % nx;
+            int iy = pixel / nx;
 
-        float value = image->data.F32[iy][ix];
-        min = PS_MIN(value, min);
-        max = PS_MIN(value, max);
-        values->data.F32[n] = value;
-        n++;
+            if (!isfinite(image->data.F32[iy][ix]) || (mask && mask->data.PS_TYPE_IMAGE_MASK_DATA[iy][ix] & maskValue)) {
+                continue;
+            }
+
+            float value = image->data.F32[iy][ix];
+            min = PS_MIN(value, min);
+            max = PS_MAX(value, max);
+            values->data.F32[n] = value;
+            n++;
+        }
     }
     if (n < 0.01*Nsubset) {