Update app.py

app.py

@@ -875,8 +875,8 @@ async def read_root():
                 reader.onload = function(e) {
                     const img = new Image();
                     img.onload = function() {
-                        const maxWidth = 860;
-                        const maxHeight = 860;
+                        const maxWidth = 640;
+                        const maxHeight = 640;
                         let width = img.width;
                         let height = img.height;
                         if (width > maxWidth || height > maxHeight) {