pass image as reference

src/descriptors/dct.rs

@@ -101,7 +101,7 @@ impl DCT {
 }
 
 impl Descriptor for DCT {
-    fn describe(&self, img: image::DynamicImage) -> u64 {
+    fn describe(&self, img: &image::DynamicImage) -> u64 {
         let resized = self.resize(img);
         let mut dct_values = self.dct(&resized);
         debug!("DCT-coefficients:\n {}", print_matrix(dct_values));

src/descriptors/mod.rs

@@ -2,10 +2,10 @@ pub trait Descriptor {
     fn info(&self) -> String {
         "Descriptor".to_string()
     }
-    fn resize(&self, img: image::DynamicImage) -> image::DynamicImage {
+    fn resize(&self, img: &image::DynamicImage) -> image::DynamicImage {
         img.grayscale().thumbnail_exact(8, 8)
     }
-    fn describe(&self, img: image::DynamicImage) -> u64;
+    fn describe(&self, img: &image::DynamicImage) -> u64;
     fn distance(&self, a: u64, b: u64) -> u64 {
         (a^b).count_ones().into()
     }