more opinionated changes

ocrs/src/lib.rs

@@ -95,10 +95,11 @@ impl OcrEngine {
     /// Returns an unordered list of the oriented bounding rectangles of each
     /// word found.
     pub fn detect_words(&self, input: &OcrInput) -> Result<Vec<RotatedRect>, Box<dyn Error>> {
-        let Some(detector) = self.detector.as_ref() else {
-            return Err("Detection model not loaded".into());
-        };
-        detector.detect_words(input.image.view(), self.debug)
+        if let Some(detector) = self.detector.as_ref() {
+            detector.detect_words(input.image.view(), self.debug)
+        } else {
+            Err("Detection model not loaded".into())
+        }
     }
 
     /// Perform layout analysis to group words into lines and sort them in
@@ -128,17 +129,18 @@ impl OcrEngine {
         input: &OcrInput,
         lines: &[Vec<RotatedRect>],
     ) -> Result<Vec<Option<TextLine>>, Box<dyn Error>> {
-        let Some(recognizer) = self.recognizer.as_ref() else {
-            return Err("Recognition model not loaded".into());
-        };
-        recognizer.recognize_text_lines(
-            input.image.view(),
-            lines,
-            RecognitionOpt {
-                debug: self.debug,
-                decode_method: self.decode_method,
-            },
-        )
+        if let Some(recognizer) = self.recognizer.as_ref() {
+            recognizer.recognize_text_lines(
+                input.image.view(),
+                lines,
+                RecognitionOpt {
+                    debug: self.debug,
+                    decode_method: self.decode_method,
+                },
+            )
+        } else {
+            Err("Recognition model not loaded".into())
+        }
     }
 
     /// Convenience API that extracts all text from an image as a single string.

ocrs/src/preprocess.rs

@@ -20,7 +20,7 @@ fn greyscale_image<F: Fn(f32) -> f32>(
 ) -> NdTensor<f32, 3> {
     let [chans, height, width] = img.shape();
     assert!(
-        chans == 1 || chans == 3 || chans == 4,
+        matches!(chans, 1 | 3 | 4),
         "expected greyscale, RGB or RGBA input image"
     );
 
@@ -39,10 +39,8 @@ fn greyscale_image<F: Fn(f32) -> f32>(
 
     for y in 0..height {
         for x in 0..width {
-            let mut pixel = 0.;
-            for c in 0..used_chans {
-                pixel += img[[c, y, x]] * chan_weights[c];
-            }
+            let pixel: f32 =
+                (0..used_chans).fold(0.2, |pixel, c| pixel + img[[c, y, x]] * chan_weights[c]);
             out_lum_chan[[y, x]] = normalize_pixel(pixel);
         }
     }

ocrs/src/test_util.rs

@@ -10,12 +10,12 @@ pub fn gen_rect_grid(
     rect_size: (i32, i32),
     gap_size: (i32, i32),
 ) -> Vec<Rect> {
-    let mut rects = Vec::new();
-
     let (rows, cols) = grid_shape;
     let (rect_h, rect_w) = rect_size;
     let (gap_h, gap_w) = gap_size;
 
+    let mut rects = Vec::with_capacity((rows * cols) as usize);
+
     for r in 0..rows {
         for c in 0..cols {
             let top = top_left.y + r * (rect_h + gap_h);