fix(pixelation): exclude external and transparent cells from color counting

src/app/page.tsx

@@ -835,7 +835,7 @@ export default function Home() {
       // 2. 统计初始颜色数量
       const initialColorCounts: { [key: string]: number } = {};
       initialMappedData.flat().forEach(cell => {
-          if (cell && cell.key) {
+          if (cell && cell.key && !cell.isExternal && cell.key !== TRANSPARENT_KEY) {
               initialColorCounts[cell.key] = (initialColorCounts[cell.key] || 0) + 1;
           }
       });
@@ -854,7 +854,7 @@ export default function Home() {
       
       // 4. 复制初始数据，准备合并
       const mergedData: MappedPixel[][] = initialMappedData.map(row => 
-          row.map(cell => ({...cell, isExternal: false}))
+          row.map(cell => ({ ...cell, isExternal: cell.isExternal ?? false }))
       );
       
       // 5. 处理相似颜色合并

src/utils/pixelation.ts

@@ -1,3 +1,5 @@
+import { transparentColorData } from './pixelEditingUtils';
+
 // 定义像素化模式
 export enum PixelationMode {
   Dominant = 'dominant', // 卡通模式（主色）
@@ -207,12 +209,12 @@ export function calculatePixelGrid(
                 const closestBead = findClosestPaletteColor(representativeRgb, palette);
                 finalCellColorData = { key: closestBead.key, color: closestBead.hex };
             } else {
-                // 如果单元格为空或全透明，使用备用色
-                finalCellColorData = { key: t1FallbackColor.key, color: t1FallbackColor.hex };
+                // 如果单元格为空或全透明，标记为透明/外部
+                finalCellColorData = { ...transparentColorData };
             }
             mappedData[j][i] = finalCellColorData;
         }
     }
     console.log(`Pixel grid calculation complete for mode: ${mode}`);
     return mappedData;
-} 
+}