From f64365f5bd4991c49ccd934dda34348b5eda207e Mon Sep 17 00:00:00 2001
From: Vinzenz Schroeter <vinzenz.f.s@gmail.com>
Date: Fri, 28 Feb 2025 12:12:39 +0100
Subject: [PATCH] implement sharpen

---
 src/ledwand_dither.rs | 24 ++++++++++++++++++++++++
 src/stream_window.rs  | 10 ++++++++--
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/src/ledwand_dither.rs b/src/ledwand_dither.rs
index ce92b03..135515c 100644
--- a/src/ledwand_dither.rs
+++ b/src/ledwand_dither.rs
@@ -127,6 +127,13 @@ impl LedwandDither {
         Self::blur_inner_pixels(source, destination);
     }
 
+    pub fn sharpen(source: &GrayImage, destination: &mut GrayImage) {
+        assert_eq!(source.len(), destination.len());
+
+        Self::copy_border(source, destination);
+        Self::sharpen_inner_pixels(source, destination);
+    }
+
     fn copy_border(source: &GrayImage, destination: &mut GrayImage) {
         let last_row = source.height() -1;
         for x in 0..source.width() {
@@ -157,4 +164,21 @@ impl LedwandDither {
             }
         }
     }
+
+    fn sharpen_inner_pixels(source: &GrayImage, destination: &mut GrayImage) {
+        for y in 1..source.height() - 2 {
+            for x in 1..source.width() - 2 {
+                let weighted_sum = -(source.get_pixel(x - 1, y - 1).0[0] as i32)
+                    - source.get_pixel(x, y - 1).0[0] as i32
+                    - source.get_pixel(x + 1, y - 1).0[0] as i32
+                    - source.get_pixel(x - 1, y).0[0] as i32
+                    + 9 * source.get_pixel(x, y).0[0] as i32
+                    - source.get_pixel(x + 1, y).0[0] as i32
+                    - source.get_pixel(x - 1, y + 1).0[0] as i32
+                    - source.get_pixel(x, y + 1).0[0] as i32
+                    - source.get_pixel(x + 1, y + 1).0[0] as i32;
+                destination.get_pixel_mut(x, y).0[0] = weighted_sum.clamp(u8::MIN as i32, u8::MAX as i32) as u8;
+            }
+        }
+    }
 }
diff --git a/src/stream_window.rs b/src/stream_window.rs
index 5ab7c3d..0358c61 100644
--- a/src/stream_window.rs
+++ b/src/stream_window.rs
@@ -29,11 +29,17 @@ pub fn stream_window(connection: &Connection, options: StreamScreenOptions) {
     loop {
         let mut frame = get_next_frame(&capturer);
 
+        LedwandDither::histogram_correction(&mut frame);
+
+        let mut orig = frame.clone();
+        LedwandDither::blur(&orig, &mut frame);
+
+        std::mem::swap(&mut frame, &mut orig);
+        LedwandDither::sharpen(&orig, &mut frame);
+
         let cutoff = if options.no_dither {
             LedwandDither::median_brightness(&frame)
         } else {
-            LedwandDither::histogram_correction(&mut frame);
-            LedwandDither::blur(&frame.clone(), &mut frame);
             dither(&mut frame, &BiLevel);
             u8::MAX / 2
         };