fix foolishness

Signed-off-by: Larry Gritz <lg@larrygritz.com>
AcademySoftwareFoundation · Jun 27, 2024 · ddf61cd · ddf61cd
1 parent 9c4d882
commit ddf61cd
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Showing 3 changed files with 23 additions and 19 deletions.
diff --git a/src/png.imageio/pnginput.cpp b/src/png.imageio/pnginput.cpp
@@ -236,27 +236,31 @@ PNGInput::associateAlpha(T* data, int size, int channels, int alpha_channel,
                 for (int c = 0; c < channels; c++) {
                     if (c != alpha_channel) {
                         float f = sRGB_to_linear(val[c]);
-                        val[c] = linear_to_sRGB(f * alpha);
+                        val[c]  = linear_to_sRGB(f * alpha);
                     }
                 }
             }
         }
     } else if (gamma == 1.0f) {
-        T max = std::numeric_limits<T>::max();
-        for (int x = 0; x < size; ++x, data += channels)
-            for (int c = 0; c < channels; c++)
-                if (c != alpha_channel) {
-                    unsigned int f = data[c];
-                    data[c]        = (f * data[alpha_channel]) / max;
-                }
+        for (int x = 0; x < size; ++x, data += channels) {
+            DataArrayProxy<T, float> val(data);
+            float alpha = val[alpha_channel];
+            if (alpha != 0.0f && alpha != 1.0f) {
+                for (int c = 0; c < channels; c++)
+                    if (c != alpha_channel)
+                        data[c] = data[c] * alpha;
+            }
+        }
     } else {  // With gamma correction
         float inv_gamma = 1.0f / gamma;
         for (int x = 0; x < size; ++x, data += channels) {
             DataArrayProxy<T, float> val(data);
             float alpha = val[alpha_channel];
-            for (int c = 0; c < channels; c++)
-                if (c != alpha_channel)
-                    val[c] = powf((powf(data[c], inv_gamma)) * alpha, gamma);
+            if (alpha != 0.0f && alpha != 1.0f) {
+                for (int c = 0; c < channels; c++)
+                    if (c != alpha_channel)
+                        val[c] = powf((powf(val[c], gamma)) * alpha, inv_gamma);
+            }
         }
     }
 }

diff --git a/testsuite/png/ref/out-libpng15.txt b/testsuite/png/ref/out-libpng15.txt
@@ -36,15 +36,15 @@ exif.png             :   64 x   64, 3 channel, uint8 png
     Exif:ImageHistory: "oiiotool -no-autopremult SLEEP_MM.png -cut 1x1+227+1211 -o kaka.png"
     oiio:ColorSpace: "Gamma2.2"
     oiio:Gamma: 2.2
-    Stats Min: 185 185 185 127 (of 255)
-    Stats Max: 185 185 185 127 (of 255)
-    Stats Avg: 185.00 185.00 185.00 127.00 (of 255)
+    Stats Min: 186 186 186 127 (of 255)
+    Stats Max: 186 186 186 127 (of 255)
+    Stats Avg: 186.00 186.00 186.00 127.00 (of 255)
     Stats StdDev: 0.00 0.00 0.00 0.00 (of 255)
     Stats NanCount: 0 0 0 0 
     Stats InfCount: 0 0 0 0 
     Stats FiniteCount: 1 1 1 1 
     Constant: Yes
-    Constant Color: 185.00 185.00 185.00 127.00 (of 255)
+    Constant Color: 186.00 186.00 186.00 127.00 (of 255)
     Monochrome: No
 smallalpha.png       :    1 x    1, 4 channel, uint8 png
     Pixel (0, 0): 240 108 119 1 (0.94117653 0.42352945 0.4666667 0.003921569)

diff --git a/testsuite/png/ref/out.txt b/testsuite/png/ref/out.txt
@@ -40,15 +40,15 @@ exif.png             :   64 x   64, 3 channel, uint8 png
     Exif:ImageHistory: "oiiotool -no-autopremult SLEEP_MM.png -cut 1x1+227+1211 -o kaka.png"
     oiio:ColorSpace: "Gamma2.2"
     oiio:Gamma: 2.2
-    Stats Min: 185 185 185 127 (of 255)
-    Stats Max: 185 185 185 127 (of 255)
-    Stats Avg: 185.00 185.00 185.00 127.00 (of 255)
+    Stats Min: 186 186 186 127 (of 255)
+    Stats Max: 186 186 186 127 (of 255)
+    Stats Avg: 186.00 186.00 186.00 127.00 (of 255)
     Stats StdDev: 0.00 0.00 0.00 0.00 (of 255)
     Stats NanCount: 0 0 0 0 
     Stats InfCount: 0 0 0 0 
     Stats FiniteCount: 1 1 1 1 
     Constant: Yes
-    Constant Color: 185.00 185.00 185.00 127.00 (of 255)
+    Constant Color: 186.00 186.00 186.00 127.00 (of 255)
     Monochrome: No
 smallalpha.png       :    1 x    1, 4 channel, uint8 png
     Pixel (0, 0): 240 108 119 1 (0.94117653 0.42352945 0.4666667 0.003921569)