diff --git a/src-tauri/Cargo.lock b/src-tauri/Cargo.lock
index bac3e48..68235b0 100644
--- a/src-tauri/Cargo.lock
+++ b/src-tauri/Cargo.lock
@@ -563,6 +563,12 @@ version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0bd4b30a6560bbd9b4620f4de34c3f14f60848e58a9b7216801afcb4c7b31c3c"
 
+[[package]]
+name = "either"
+version = "1.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7fcaabb2fef8c910e7f4c7ce9f67a1283a1715879a7c230ca9d6d1ae31f16d91"
+
 [[package]]
 name = "embed_plist"
 version = "1.2.2"
@@ -1266,6 +1272,15 @@ dependencies = [
  "windows-sys 0.45.0",
 ]
 
+[[package]]
+name = "itertools"
+version = "0.10.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b0fd2260e829bddf4cb6ea802289de2f86d6a7a690192fbe91b3f46e0f2c8473"
+dependencies = [
+ "either",
+]
+
 [[package]]
 name = "itoa"
 version = "0.4.8"
@@ -2758,6 +2773,7 @@ dependencies = [
  "display-info",
  "env_logger",
  "hex",
+ "itertools",
  "log",
  "paho-mqtt",
  "paris",
diff --git a/src-tauri/Cargo.toml b/src-tauri/Cargo.toml
index 29f282c..edd8ba8 100644
--- a/src-tauri/Cargo.toml
+++ b/src-tauri/Cargo.toml
@@ -30,6 +30,7 @@ hex = "0.4.3"
 toml = "0.7.3"
 paho-mqtt = "0.12.1"
 time = {version="0.3.20", features= ["formatting"] }
+itertools = "0.10.5"
 
 [features]
 # this feature is used for production builds or when `devPath` points to the filesystem
diff --git a/src-tauri/src/ambient_light/config.rs b/src-tauri/src/ambient_light/config.rs
index 5d25d88..8012120 100644
--- a/src-tauri/src/ambient_light/config.rs
+++ b/src-tauri/src/ambient_light/config.rs
@@ -1,4 +1,4 @@
-use std::env::current_dir;
+use std::{env::current_dir, fmt::format};
 
 use paris::{error, info};
 use serde::{Deserialize, Serialize};
@@ -56,6 +56,8 @@ impl LedStripConfigGroup {
             let config: LedStripConfigGroup = toml::from_str(&config)
                 .map_err(|e| anyhow::anyhow!("Failed to parse config file: {}", e))?;
 
+            log::info!("config loaded: {:?}", config.strips.iter().map(|c| format!("{}#{}", c.index, c.display_id)).collect::<Vec<_>>());
+
             Ok(config)
         } else {
             info!("config file not exist, fallback to default config");
diff --git a/src-tauri/src/ambient_light/config_manager.rs b/src-tauri/src/ambient_light/config_manager.rs
index bcde3ec..9a21ced 100644
--- a/src-tauri/src/ambient_light/config_manager.rs
+++ b/src-tauri/src/ambient_light/config_manager.rs
@@ -5,7 +5,7 @@ use tokio::sync::OnceCell;
 
 use crate::ambient_light::{config, LedStripConfigGroup};
 
-use super::Border;
+use super::{Border, SamplePointMapper};
 
 pub struct ConfigManager {
     config: Arc<RwLock<LedStripConfigGroup>>,
@@ -62,19 +62,21 @@ impl ConfigManager {
     ) -> anyhow::Result<()> {
         let mut config = self.config.write().await;
 
-        for config in config.strips.iter_mut() {
-            if config.display_id == display_id && config.border == border {
-                let target = config.len as i64 + delta_len as i64;
+        for strip in config.strips.iter_mut() {
+            if strip.display_id == display_id && strip.border == border {
+                let target = strip.len as i64 + delta_len as i64;
                 if target < 0 || target > 1000 {
                     return Err(anyhow::anyhow!(
                         "Overflow. range: 0-1000, current: {}",
                         target
                     ));
                 }
-                config.len = target as usize;
+                strip.len = target as usize;
             }
         }
 
+        Self::rebuild_mappers(&mut config);
+
         let cloned_config = config.clone();
 
         drop(config);
@@ -88,6 +90,24 @@ impl ConfigManager {
         Ok(())
     }
 
+    fn rebuild_mappers(config: &mut LedStripConfigGroup) {
+        let mut prev_end = 0;
+        let mappers: Vec<SamplePointMapper> = config
+            .strips
+            .iter()
+            .map(|strip| {
+                let mapper = SamplePointMapper {
+                    start: prev_end,
+                    end: prev_end + strip.len,
+                };
+                prev_end = mapper.end;
+                mapper
+            })
+            .collect();
+
+        config.mappers = mappers;
+    }
+
     pub async fn set_items(&self, items: Vec<config::LedStripConfig>) -> anyhow::Result<()> {
         let mut config = self.config.write().await;
 
diff --git a/src-tauri/src/ambient_light/publisher.rs b/src-tauri/src/ambient_light/publisher.rs
index 0597208..08c1cd1 100644
--- a/src-tauri/src/ambient_light/publisher.rs
+++ b/src-tauri/src/ambient_light/publisher.rs
@@ -10,6 +10,8 @@ use crate::{
     screenshot_manager::ScreenshotManager,
 };
 
+use itertools::Itertools;
+
 pub struct LedColorsPublisher {
     rx: Arc<RwLock<watch::Receiver<Vec<u8>>>>,
     tx: Arc<RwLock<watch::Sender<Vec<u8>>>>,
@@ -45,15 +47,30 @@ impl LedColorsPublisher {
                 let configs = config_manager.configs().await;
                 let channels = screenshot_manager.channels.read().await;
 
+                let display_ids = configs
+                    .strips
+                    .iter()
+                    .map(|c| c.display_id)
+                    .unique().collect::<Vec<_>>();
+
                 let mut colors_configs = Vec::new();
 
-                for (display_id, rx) in channels.iter() {
+                for display_id in display_ids {
                     let led_strip_configs: Vec<_> = configs
                         .strips
                         .iter()
-                        .filter(|c| c.display_id == *display_id)
+                        .filter(|c| c.display_id == display_id)
                         .collect();
 
+                    let rx = channels.get(&display_id);
+
+                    if rx.is_none() {
+                        warn!("no channel for display_id: {}", display_id);
+                        continue;
+                    }
+
+                    let rx = rx.unwrap();
+
                     if led_strip_configs.len() == 0 {
                         warn!("no led strip config for display_id: {}", display_id);
                         continue;
@@ -72,14 +89,16 @@ impl LedColorsPublisher {
                             .collect();
 
                         let colors_config = config::SamplePointConfig {
-                            display_id: *display_id,
+                            display_id,
                             points,
                         };
 
                         colors_configs.push(colors_config);
                     }
                 }
-                let colors = screenshot_manager.get_all_colors(&colors_configs, &configs.mappers, &channels).await;
+                let colors = screenshot_manager
+                    .get_all_colors(&colors_configs, &configs.mappers, &channels)
+                    .await;
                 match tx.send(colors) {
                     Ok(_) => {
                         // log::info!("colors updated");
diff --git a/src-tauri/src/screenshot_manager.rs b/src-tauri/src/screenshot_manager.rs
index d21e054..b0139ed 100644
--- a/src-tauri/src/screenshot_manager.rs
+++ b/src-tauri/src/screenshot_manager.rs
@@ -226,6 +226,7 @@ impl ScreenshotManager {
 
         let mut global_colors = vec![0u8; total_leds * 3];
         let mut all_colors = vec![];
+
         for config in configs {
             let rx = channels.get(&config.display_id);
             if rx.is_none() {
@@ -244,11 +245,12 @@ impl ScreenshotManager {
 
         let mut color_index = 0;
         mappers.iter().for_each(|group| {
-            if group.end >= all_colors.len() || group.start >= all_colors.len() {
+            if group.end > all_colors.len() || group.start > all_colors.len() {
+                warn!("get_all_colors: group out of range. start: {}, end: {}, all_colors.len(): {}", group.start, group.end, all_colors.len());
                 return;
-            } 
+            }
             if group.end > group.start {
-                for i in group.start..group.end - 1 {
+                for i in group.start..group.end {
                     let rgb = all_colors[color_index].get_rgb();
                     color_index += 1;
 
@@ -257,7 +259,7 @@ impl ScreenshotManager {
                     global_colors[i * 3 + 2] = rgb[2];
                 }
             } else {
-                for i in (group.end..group.start - 1).rev() {
+                for i in (group.end..group.start).rev() {
                     let rgb = all_colors[color_index].get_rgb();
                     color_index += 1;