feat: add negative prompt support in Advanced Settings

app.py

@@ -74,8 +74,16 @@ def load_pipeline():
     return pipe
 
 
+# Default negative prompt to avoid common issues
+DEFAULT_NEGATIVE_PROMPT = (
+    "white background, pale background, washed out, overexposed, "
+    "low contrast, blurry, out of focus, multiple cells, overlapping cells, "
+    "artifacts, noise, low quality, deformed"
+)
+
+
 @spaces.GPU(duration=30)
-def generate(cell_type, custom_prompt, cfg, steps, seed):
+def generate(cell_type, custom_prompt, cfg, steps, seed, negative_prompt, use_negative_prompt):
     """Generate a blood cell image. GPU is allocated for this function."""
     import random
 
@@ -91,8 +99,14 @@ def generate(cell_type, custom_prompt, cfg, steps, seed):
 
     generator = torch.Generator(device="cuda").manual_seed(actual_seed)
 
+    # Prepare negative prompt
+    neg_prompt = None
+    if use_negative_prompt:
+        neg_prompt = negative_prompt.strip() if negative_prompt and negative_prompt.strip() else DEFAULT_NEGATIVE_PROMPT
+
     result = pipeline(
         prompt=prompt,
+        negative_prompt=neg_prompt,
         height=512,
         width=512,
         num_inference_steps=int(steps),
@@ -155,6 +169,21 @@ with gr.Blocks(css=custom_css, theme=gr.themes.Soft(primary_hue="red")) as demo:
                     info="Number of denoising steps. More steps = higher quality but slower generation. Recommended: 20-30."
                 )
 
+                gr.Markdown("---")
+
+                use_negative_checkbox = gr.Checkbox(
+                    value=True,
+                    label="Use Negative Prompt",
+                    info="Enable to steer generation away from unwanted characteristics"
+                )
+                negative_prompt_box = gr.Textbox(
+                    value=DEFAULT_NEGATIVE_PROMPT,
+                    label="Negative Prompt",
+                    placeholder="Describe what you DON'T want in the image...",
+                    lines=2,
+                    info="The model will avoid these characteristics. Helps prevent pale/washed out backgrounds and blurry images."
+                )
+
             btn = gr.Button("Generate Cell Image", variant="primary", elem_classes=["primary-btn"])
 
         with gr.Column(scale=1):
@@ -180,7 +209,7 @@ with gr.Blocks(css=custom_css, theme=gr.themes.Soft(primary_hue="red")) as demo:
 
     btn.click(
         fn=generate,
-        inputs=[cell_dropdown, custom_box, cfg_slider, steps_slider, seed_box],
+        inputs=[cell_dropdown, custom_box, cfg_slider, steps_slider, seed_box, negative_prompt_box, use_negative_checkbox],
         outputs=output_img
     )