It was the gamma being wrong. Interesting how much different this is working than SFML+OpenCL

src/main.rs

@@ -78,7 +78,7 @@ fn main() {
     processor.compile_kernel(String::from("simple-edge.compute"));
     processor.compile_shaders(String::from("simple_texture"), &surface);
 
-    processor.load_buffers(String::from("funky-bird.jpg"));
+    processor.load_buffers(String::from("background.jpg"));
 
 
     let mut timer = Timer::new();