fixed output image degradation

app.py

@@ -151,6 +151,7 @@ with gr.Blocks(fill_height=True) as demo:
             output_image = gr.Image(
                 label="Generated Image",
                 type="pil",
+                format='png',
                 show_label=False,
                 height=600,
                 buttons=["download", "share"],