fast mode

1 files changed, 15 insertions, 7 deletions

diff --git a/evc/src/helpers/pixel.rs b/evc/src/helpers/pixel.rs
index 964040d..816d7dc 100644
--- a/evc/src/helpers/pixel.rs
+++ b/evc/src/helpers/pixel.rs
@@ -27,17 +27,16 @@ impl Pixel {
             a.r.abs_diff(b.r) as usize,
             a.r.abs_diff(b.r) as usize,
         );
+        // fast_sqrt(rd * rd + gd * gd + bd * bd)
         SQRT[rd + gd + bd]
     }
-    
+
     #[inline]
     pub fn average(a: Pixel, b: Pixel) -> Pixel {
-        //? this functions is broken
-        // TODO dont loose accuracy
         Pixel {
-            r: (a.r >> 1) + (b.r >> 1),
-            g: (a.g >> 1) + (b.g >> 1),
-            b: (a.b >> 1) + (b.b >> 1),
+            r: ((a.r as u16 + b.r as u16) >> 1) as u8,
+            g: ((a.g as u16 + b.g as u16) >> 1) as u8,
+            b: ((a.b as u16 + b.b as u16) >> 1) as u8,
         }
     }
 
@@ -51,7 +50,7 @@ impl Pixel {
     }
 }
 
-const SQRT: [usize; 256 * 3] = gen_sqrt_lookup();
+pub const SQRT: [usize; 256 * 3] = gen_sqrt_lookup();
 
 const fn gen_sqrt_lookup<const N: usize>() -> [usize; N] {
     let mut arr = [0; N];
@@ -70,3 +69,12 @@ const fn sqrt(x: f32) -> f32 {
     let a = (a + x / a) * 0.5;
     a
 }
+
+pub fn fast_sqrt(x: usize) -> usize {
+    let a = 1;
+    let a = (a + x / (a + 1)) / 2;
+    let a = (a + x / (a + 1)) / 2;
+    // let a = (a + x / (a + 1)) / 2;
+    // let a = (a + x / (a + 1)) / 2;
+    a
+}