flatten background while convert transparent image

Author: smmehdisharifi

src/Utility/Image.php

@@ -19,6 +19,10 @@ public function resize(string $disk, string $sourceFile, string $targetFile, int
             Storage::disk($disk)->get($sourceFile)
         );
 
+        if ($image->hasAlpha()) {
+            $image = $image->flatten(['background' => [255, 255, 255]]);
+        }
+
         $width = min($image->width, $width);
         $height = min($image->height, $height);
         $ext = pathinfo($targetFile, PATHINFO_EXTENSION);
@@ -45,6 +49,10 @@ public function convert(string $disk, string $sourceFile, string $targetFile): v
             Storage::disk($disk)->get($sourceFile)
         );
 
+        if ($image->hasAlpha()) {
+            $image = $image->flatten(['background' => [255, 255, 255]]);
+        }
+
         $ext = pathinfo($targetFile, PATHINFO_EXTENSION);
 
         $saved = Storage::disk($disk)->put(