Apply normalisation before flatten

shaojing1779 · May 21, 2022 · cb1df11 · cb1df11
1 parent b4c7a1d
commit cb1df11
Showing 1 changed file with 6 additions and 5 deletions.
diff --git a/test/api/similar_image.cpp b/test/api/similar_image.cpp
@@ -1,13 +1,11 @@
 #include "similar_image.h"
 
+#include <array>
 #include <iomanip>
 
 VImage SimilarImage::normalize(const VImage &image) const {
     // Get original colorspace
     VipsInterpretation type_before_normalize = image.interpretation();
-    if (type_before_normalize == VIPS_INTERPRETATION_RGB) {
-        type_before_normalize = VIPS_INTERPRETATION_sRGB;
-    }
 
     // Convert to LAB colorspace
     VImage lab = image.colourspace(VIPS_INTERPRETATION_LAB);
@@ -57,6 +55,9 @@ std::string SimilarImage::dhash(const VImage &image) const {
     VImage thumbnail =
         image.thumbnail_image(9, thumbnail_options).copy_memory();
 
+    // Apply normalisation - stretch luminance to cover full dynamic range.
+    thumbnail = normalize(thumbnail);
+
     // Flatten it to mid-gray before generating a fingerprint.
     if (image.has_alpha()) {
         std::vector<double> background{128, 128, 128};  // #808080
@@ -65,9 +66,9 @@ std::string SimilarImage::dhash(const VImage &image) const {
             thumbnail.flatten(VImage::option()->set("background", background));
     }
 
-    thumbnail = normalize(thumbnail).colourspace(VIPS_INTERPRETATION_B_W)[0];
+    thumbnail = thumbnail.colourspace(VIPS_INTERPRETATION_B_W)[0];
 
-    auto dhash_image =
+    auto *dhash_image =
         static_cast<uint8_t *>(thumbnail.write_to_memory(nullptr));
 
     // Calculate dHash