From 8417562e310273989c5a77250d84b51493266550 Mon Sep 17 00:00:00 2001
From: saji <saji@saji.dev>
Date: Wed, 17 Jul 2024 10:20:06 -0500
Subject: [PATCH] switch to atkinson dithering

---
 build.sh         |  6 +++---
 src/imageproc.rs | 12 ++++++++++--
 src/main.rs      |  2 +-
 3 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/build.sh b/build.sh
index 2c09499..711ed94 100755
--- a/build.sh
+++ b/build.sh
@@ -1,6 +1,6 @@
 #!/bin/bash
 set +x
-cross build --target aarch64-unknown-linux-gnu --release
-rsync -aczP target/aarch64-unknown-linux-gnu/release/pi-frame-server 192.168.0.186:
+cross build --target aarch64-unknown-linux-gnu --release --features eink
+rsync -aczP target/aarch64-unknown-linux-gnu/release/pi-frame-server 192.168.0.185:
 # scp target/aarch64-unknown-linux-gnu/debug/pi-frame-server 192.168.0.186:
-ssh 192.168.0.186 ./pi-frame-server load
+ssh 192.168.0.185 ./pi-frame-server show
diff --git a/src/imageproc.rs b/src/imageproc.rs
index 16c353b..ac5f95f 100644
--- a/src/imageproc.rs
+++ b/src/imageproc.rs
@@ -141,7 +141,7 @@ pub fn nearest_neighbor(input_color: Lab) -> (DisplayColor, Lab) {
         .enumerate()
         .map(|(idx, p_color)| {
             let c: Lab = (*p_color).into_color();
-            (idx, input_color.distance_squared(c), input_color - c)
+            (idx, input_color.difference(c), input_color - c)
         })
         .min_by(|(_, a, _), (_, b, _)| a.total_cmp(b))
         .expect("could not find a color");
@@ -207,6 +207,14 @@ const FLOYD_STEINBERG: [DiffusionPoint; 4] = [
     DiffusionPoint::new(0, 1, 5.0 / 16.0),
     DiffusionPoint::new(1, 1, 1.0 / 16.0),
 ];
+const ATKINSON_DITHER: [DiffusionPoint; 6] = [
+    DiffusionPoint::new(1, 0, 1.0/8.0),
+    DiffusionPoint::new(2, 0, 1.0/8.0),
+    DiffusionPoint::new(-1, 1, 1.0/8.0),
+    DiffusionPoint::new(0, 1, 1.0/8.0),
+    DiffusionPoint::new(1, 1, 1.0/8.0),
+    DiffusionPoint::new(0, 2, 1.0/8.0),
+];
 
 impl Ditherer for FloydSteinbergDither {
     fn dither(&mut self, img: &RgbImage, output: &mut EInkBuffer) {
@@ -227,7 +235,7 @@ impl Ditherer for FloydSteinbergDither {
                 // set the color in the output buffer.
                 output.0[index] = nearest;
                 // take the error, and propagate it.
-                for point in FLOYD_STEINBERG {
+                for point in ATKINSON_DITHER {
                     let Some(target_x) = x.checked_add_signed(point.xshift) else {
                         continue;
                     };
diff --git a/src/main.rs b/src/main.rs
index 3dce30d..4cba245 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -36,7 +36,7 @@ fn main() -> anyhow::Result<()> {
         let mut display = Wrapper::new()?;
 
         let mut eink_buf = EInkBuffer::new(800, 480);
-        let mut dither = NNDither{};
+        let mut dither = FloydSteinbergDither{};
 
         dither.dither(&img, &mut eink_buf);
         let raw_buf = eink_buf.into_display_buffer();