From: Urban Wallasch <urban.wallasch@freenet.de>
Date: Sun, 6 Jun 2021 13:24:24 +0000 (+0200)
Subject: * Sped up perceptual hashing by switching from Gaussian to Box blur.
X-Git-Url: https://git.packet-gain.de/?a=commitdiff_plain;h=11e96905854c41236bd447f4c679e4c8cddf068a;p=imgdupe.git

* Sped up perceptual hashing by switching from Gaussian to Box blur.
---

diff --git a/README.md b/README.md
index f8e2ee6..6871076 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,7 @@ The perceptual hash for an image is calculated by:
 
   * flattening the image (merging layers/frames)
   * transforming the color space to gray scale
-  * resizing to 16 by 16 pixel while applying Gaussian blur
+  * resizing to 16 by 16 pixel using box blur
   * normalizing contrast and brightness
   * conversion to monochromatic image
   * interpreting the pixel values as 256 bit hash value
diff --git a/db.c b/db.c
index 644a350..4990d8e 100644
--- a/db.c
+++ b/db.c
@@ -47,7 +47,7 @@ static int phash(db_entry_t *p, double blur) {
         goto ERR2;
     wand2 = MagickFlattenImages(wand);
     MagickSetImageColorspace(wand2, GRAYColorspace);
-    MagickResizeImage(wand2, 16, 16, GaussianFilter, blur);
+    MagickResizeImage(wand2, 16, 16, BoxFilter, blur);
     MagickNormalizeImage(wand2);
     MagickGetImagePixels(wand2, 0, 0, 16, 16, "I", CharPixel, pix);
     uint64_t h = 0;