Revert some changes that made the pipeline slower.

src/pipeline/steps/alignment.rs

@@ -280,21 +280,15 @@ fn apply_affine_transform(
         let r = (p00[0] as f32 * (1.0 - dx) * (1.0 - dy)
             + p10[0] as f32 * dx * (1.0 - dy)
             + p01[0] as f32 * (1.0 - dx) * dy
-            + p11[0] as f32 * dx * dy)
-            .round()
-            .clamp(0.0, 255.0) as u8;
+            + p11[0] as f32 * dx * dy) as u8;
         let g = (p00[1] as f32 * (1.0 - dx) * (1.0 - dy)
             + p10[1] as f32 * dx * (1.0 - dy)
             + p01[1] as f32 * (1.0 - dx) * dy
-            + p11[1] as f32 * dx * dy)
-            .round()
-            .clamp(0.0, 255.0) as u8;
+            + p11[1] as f32 * dx * dy) as u8;
         let b = (p00[2] as f32 * (1.0 - dx) * (1.0 - dy)
             + p10[2] as f32 * dx * (1.0 - dy)
             + p01[2] as f32 * (1.0 - dx) * dy
-            + p11[2] as f32 * dx * dy)
-            .round()
-            .clamp(0.0, 255.0) as u8;
+            + p11[2] as f32 * dx * dy) as u8;
 
         Rgb([r, g, b])
     });

src/pipeline/steps/brightness.rs

@@ -10,7 +10,7 @@ use crate::pipeline::{
     ProcessingStep, StepOutcome,
 };
 use async_trait::async_trait;
-use image::{DynamicImage, Rgb};
+use image::{DynamicImage, GenericImageView, Rgb};
 
 /// Validates image brightness and skips images outside acceptable range.
 ///
@@ -35,8 +35,7 @@ impl BrightnessStep {
         x2: u32,
         y2: u32,
     ) -> f32 {
-        let luma = image.to_luma8();
-        let (img_width, img_height) = luma.dimensions();
+        let (img_width, img_height) = image.dimensions();
 
         // Clamp coordinates to image bounds
         let x1 = x1.min(img_width.saturating_sub(1));
@@ -44,26 +43,25 @@ impl BrightnessStep {
         let x2 = x2.min(img_width);
         let y2 = y2.min(img_height);
 
-        // Ensure valid region
         if x2 <= x1 || y2 <= y1 {
             return 0.0;
         }
 
-        let width = x2 - x1;
-        let height = y2 - y1;
-        let pixel_count = width as u64 * height as u64;
-
+        let pixel_count = (x2 - x1) as u64 * (y2 - y1) as u64;
         if pixel_count == 0 {
             return 0.0;
         }
 
-        // Sum luminance values from the pre-computed luma image
-        // (to_luma8 uses the standard Y = 0.299*R + 0.587*G + 0.114*B conversion)
+        // Convert only the face region to RGB (avoids converting the full image).
+        // to_rgb8() on an already-RGB8 image is a cheap clone.
+        let rgb = image.crop_imm(x1, y1, x2 - x1, y2 - y1).to_rgb8();
+
+        // Sum luminance using standard Y = 0.299*R + 0.587*G + 0.114*B.
+        // Iterate over raw bytes directly to avoid per-pixel get_pixel overhead.
         let mut total_luminance: u64 = 0;
-        for y in y1..y2 {
-            for x in x1..x2 {
-                total_luminance += luma.get_pixel(x, y)[0] as u64;
-            }
+        for chunk in rgb.as_raw().chunks_exact(3) {
+            total_luminance +=
+                (299 * chunk[0] as u64 + 587 * chunk[1] as u64 + 114 * chunk[2] as u64) / 1000;
         }
 
         (total_luminance as f32 / pixel_count as f32) / 255.0

src/pipeline/steps/head_pose.rs

@@ -235,19 +235,13 @@ impl ProcessingStep for HeadPoseStep {
             image.clone()
         };
 
-        // Run inference on the face crop (blocking CPU work offloaded from async runtime)
-        let pose = match tokio::task::spawn_blocking(move || model.estimate(&face_image)).await {
-            Ok(Ok(p)) => p,
-            Ok(Err(e)) => {
-                return StepOutcome::Error {
-                    ctx,
-                    error: format!("Head pose estimation failed: {}", e),
-                };
-            }
+        // Run inference on the face crop
+        let pose = match model.estimate(&face_image) {
+            Ok(p) => p,
             Err(e) => {
                 return StepOutcome::Error {
                     ctx,
-                    error: format!("Head pose inference task panicked: {}", e),
+                    error: format!("Head pose estimation failed: {}", e),
                 };
             }
         };