Add --invert_colors flag to fix inverted video output from certain models

- Replace unreliable auto-detection with explicit user control
- Add --invert_colors CLI argument
- Update SKILL.md documentation with usage example

SKILL.md

@@ -535,7 +535,14 @@ Auto mode detects NSFW content automatically. For explicit requests:
 python3 videogen --model <model> --prompt "<prompt>" --no_filter
 ```
 
-### 5. Reproducibility
+### 5. Color Inversion
+
+Some models (particularly certain LoRA adapters) may produce inverted colors. Fix this with:
+```bash
+python3 videogen --model wan2_2_i2v_general_nsfw_lora --image input.png --prompt "..." --invert_colors
+```
+
+### 6. Reproducibility
 
 Always capture and store the seed for reproducibility:
 ```bash

videogen.py

@@ -10238,11 +10238,9 @@ def main(args):
                             # Convert from [-1, 1] to [0, 1]
                             frames = (frames + 1.0) / 2.0
                         
-                        # Check if colors appear inverted (mostly dark images mean inverted)
-                        # Inverted images have mean > 0.5 when they should be < 0.5
-                        mean_val = np.mean(frames)
-                        if mean_val > 0.7:  # Likely inverted
-                            print(f"  ⚠️  Detected inverted colors (mean={mean_val:.2f}), correcting...")
+                        # Check if colors should be inverted (user-specified via --invert_colors)
+                        if args.invert_colors:
+                            print(f"  🎨 Inverting colors as requested (--invert_colors)...")
                             frames = 1.0 - frames
                         
                         # Now convert from [0, 1] to [0, 255]
@@ -10480,6 +10478,8 @@ List TTS voices:
                         help="Directory for output files (overrides --output path)")
     parser.add_argument("--seed", type=int, default=-1)
     parser.add_argument("--no_filter", action="store_true")
+    parser.add_argument("--invert_colors", action="store_true",
+                        help="Invert video colors after generation (fixes inverted output from some models)")
     parser.add_argument("--upscale", action="store_true")
     parser.add_argument("--upscale_factor", type=float, default=2.0)