even better image resizing logic

src/img.rs

@@ -22,11 +22,15 @@ impl ImgInfo {
         // resize so that the larger dimension is 512
         let (mut w, mut h) = resize_dimensions(img.width(), img.height(), IMG_DIM, IMG_DIM, false);
 
+        let img = img.resize_exact(w, h, FilterType::Triangle);
+
         // make both dimensions divisible by 16 (SSDV requirement)
-        w -= w % 16;
-        h -= h % 16;
+        let wdiff = w % 16;
+        let hdiff = h % 16;
+        w -= wdiff;
+        h -= hdiff;
 
-        let img = img.resize_exact(w, h, FilterType::Triangle);
+        let img = img.crop_imm(wdiff / 2, hdiff / 2, w, h);
 
         let mut bytes = vec![];