better dct maybe

src/descriptors.rs

@@ -51,24 +51,24 @@ impl Descriptor for DCT {
     fn describe(&self, img: image::DynamicImage) -> u64 {
         let mut dct_values: [f64; 64] = [0.0; 64];
         let img = self.resize(img);
-        let mut _total_sum: f64 = 0.0;
-
-        for j in 0..7 {
-            for i in 0..7 {
+        for v in 0..7 {
+            for u in 0..7 {
+                let k = (u*8)+v;
+                let v: f64 = v as f64;
+                let u: f64 = u as f64;
                 let mut sum: f64 = 0.0;
-                let k = (i*8)+j;
                 for (x, y, pix) in img.pixels() {
-                    let n: f64 = ((y*8)+x).into();
-                    let pixel: i16 = pix[0] as i16 - 127;
-                    sum += pixel as f64 * (PI/64.0 * (n + 0.5) * k as f64).cos();
+                    let x: f64 = 1.0 + 2.0 * x as f64;
+                    let y: f64 = 1.0 + 2.0 * y as f64;
+                    let pixel = (pix[0] as i16 - 127) as f64;
+                    sum +=
+                        pixel * 
+                        (x*u*PI/16.0).cos() *
+                        (y*v*PI/16.0).cos()
                 }
                 dct_values[k] = sum;
-                _total_sum += sum;
-                //println!("{sum}");
             }
         }
-        _total_sum /= 64.0;
-
         let mut mask: u64 = 0;
         for dct in dct_values {
             if dct > 0.0 {