From 31351ea91ddeab7df2cddfd4545f4c1c6e1ad3ba Mon Sep 17 00:00:00 2001
From: Mark Hoekveen <mark@hoekveen.net>
Date: Tue, 7 May 2024 01:31:26 +0200
Subject: [PATCH] refactor idct

---
 src/descriptors/dct.rs | 66 +++++++++++++++++++++++-------------------
 1 file changed, 37 insertions(+), 29 deletions(-)

diff --git a/src/descriptors/dct.rs b/src/descriptors/dct.rs
index 39b33e7..de0d91f 100644
--- a/src/descriptors/dct.rs
+++ b/src/descriptors/dct.rs
@@ -38,6 +38,41 @@ impl DCT {
         }
         quantization_matrix
     }
+
+	/// TODO
+	// pub fn dct(&self, img: image::DynamicImage) -> [f64; 64] {
+	// }
+
+	pub fn idct(&self, dct_values: [f64; 64]) -> [u8; 64] {
+        let mut reconstructed: [u8; 64] = [0; 64];
+        for k in 0..64  {
+            let x = (k%8) as f64;
+            let y = (k/8) as f64;
+            let mut sum = 0.0;
+            for u in 0..8 {
+                for v in 0..8 {
+                    let mut alpha = 1.0;
+                    if u == 0 {
+                        alpha = alpha / SQRT_2
+                    }
+                    if v == 0 {
+                        alpha = alpha / SQRT_2
+                    }
+                    let uv = (v*8)+u;
+                    let v = v as f64;
+                    let u = u as f64;
+                    sum +=
+                        alpha *
+                        dct_values[uv] *
+                        ((2.0 * x + 1.0) * u * PI / 16.0).cos() *
+                        ((2.0 * y + 1.0) * v * PI / 16.0).cos()
+                }
+            }
+            sum = 127.0 + (0.25 * sum).round();
+            reconstructed[k] = std::cmp::min(255_u8, sum as u8);
+        }
+		reconstructed
+	}
 }
 
 impl Descriptor for DCT {
@@ -48,7 +83,6 @@ impl Descriptor for DCT {
         println!("Base quantization matrix:\n{}", print_matrix(self.quantization_matrix));
         println!("Q-{} quantization matrix:\n{}", quality, print_matrix(qmatrix));
         let mut dct_values: [f64; 64] = [0.0; 64];
-        let mut reconstructed: [u8; 64] = [0; 64];
         let img = self.resize(img);
         img.save("resize.png").expect("Error saving file");
         for u in 0..8 {
@@ -88,34 +122,8 @@ impl Descriptor for DCT {
             dct_values[i] = dct_values[i] * qmatrix[i] as f64;
         }
         println!("DCT-coefficients, de-quantized:\n {}", print_matrix(dct_values));
-        for k in 0..64  {
-            let x = (k%8) as f64;
-            let y = (k/8) as f64;
-            let mut sum = 0.0;
-            for u in 0..8 {
-                for v in 0..8 {
-                    let mut alpha = 1.0;
-                    if u == 0 {
-                        alpha = alpha / SQRT_2
-                    }
-                    if v == 0 {
-                        alpha = alpha / SQRT_2
-                    }
-                    let uv = (v*8)+u;
-                    let v = v as f64;
-                    let u = u as f64;
-                    sum +=
-                        alpha *
-                        dct_values[uv] *
-                        ((2.0 * x + 1.0) * u * PI / 16.0).cos() *
-                        ((2.0 * y + 1.0) * v * PI / 16.0).cos()
-                }
-            }
-            sum = 127.0 + (0.25 * sum).round();
-            //println!("Reconstructed pixel: {}", sum);
-            reconstructed[k] = std::cmp::min(255_u8, sum as u8);
-        }
-        //println!("{}", print_matrix(reconstructed));
+		let reconstructed = self.idct(dct_values);
+        println!("Reconstructed pixel values:\n{}", print_matrix(reconstructed));
         save_buffer(
             "reconstructed.png",
             &reconstructed,