Update README.md

README.md

@@ -107,3 +107,95 @@ If you really want to play with cmd flags, you can additionally control the GPU
     --pytorch-deterministic
 
 Again, Forge do not recommend users to use any cmd flags unless you are very sure that you really need these.
+
+# Patchable UNet
+
+Now develop an extension is super simple. We finally have patchable UNet.
+
+Below is using one single file with 80 lines of codes to support FreeU:
+
+`extensions-builtin/sd_forge_freeu/scripts/forge_freeu.py`
+
+```python
+import torch
+import gradio as gr
+from modules import scripts
+
+
+def Fourier_filter(x, threshold, scale):
+    x_freq = torch.fft.fftn(x.float(), dim=(-2, -1))
+    x_freq = torch.fft.fftshift(x_freq, dim=(-2, -1))
+    B, C, H, W = x_freq.shape
+    mask = torch.ones((B, C, H, W), device=x.device)
+    crow, ccol = H // 2, W //2
+    mask[..., crow - threshold:crow + threshold, ccol - threshold:ccol + threshold] = scale
+    x_freq = x_freq * mask
+    x_freq = torch.fft.ifftshift(x_freq, dim=(-2, -1))
+    x_filtered = torch.fft.ifftn(x_freq, dim=(-2, -1)).real
+    return x_filtered.to(x.dtype)
+
+
+def set_freeu_v2_patch(model, b1, b2, s1, s2):
+    model_channels = model.model.model_config.unet_config["model_channels"]
+    scale_dict = {model_channels * 4: (b1, s1), model_channels * 2: (b2, s2)}
+
+    def output_block_patch(h, hsp, *args, **kwargs):
+        scale = scale_dict.get(h.shape[1], None)
+        if scale is not None:
+            hidden_mean = h.mean(1).unsqueeze(1)
+            B = hidden_mean.shape[0]
+            hidden_max, _ = torch.max(hidden_mean.view(B, -1), dim=-1, keepdim=True)
+            hidden_min, _ = torch.min(hidden_mean.view(B, -1), dim=-1, keepdim=True)
+            hidden_mean = (hidden_mean - hidden_min.unsqueeze(2).unsqueeze(3)) / \
+                          (hidden_max - hidden_min).unsqueeze(2).unsqueeze(3)
+            h[:, :h.shape[1] // 2] = h[:, :h.shape[1] // 2] * ((scale[0] - 1) * hidden_mean + 1)
+            hsp = Fourier_filter(hsp, threshold=1, scale=scale[1])
+        return h, hsp
+
+    m = model.clone()
+    m.set_model_output_block_patch(output_block_patch)
+    return m
+
+
+class FreeUForForge(scripts.Script):
+    def title(self):
+        return "FreeU Integrated"
+
+    def show(self, is_img2img):
+        # make this extension visible in both txt2img and img2img tab.
+        return scripts.AlwaysVisible
+
+    def ui(self, *args, **kwargs):
+        with gr.Accordion(open=False, label=self.title()):
+            freeu_enabled = gr.Checkbox(label='Enabled', value=False)
+            freeu_b1 = gr.Slider(label='B1', minimum=0, maximum=2, step=0.01, value=1.01)
+            freeu_b2 = gr.Slider(label='B2', minimum=0, maximum=2, step=0.01, value=1.02)
+            freeu_s1 = gr.Slider(label='S1', minimum=0, maximum=4, step=0.01, value=0.99)
+            freeu_s2 = gr.Slider(label='S2', minimum=0, maximum=4, step=0.01, value=0.95)
+
+        return freeu_enabled, freeu_b1, freeu_b2, freeu_s1, freeu_s2
+
+    def process_batch(self, p, *script_args, **kwargs):
+        freeu_enabled, freeu_b1, freeu_b2, freeu_s1, freeu_s2 = script_args
+
+        if not freeu_enabled:
+            return
+
+        unet = p.sd_model.forge_objects.unet
+
+        unet = set_freeu_v2_patch(unet, freeu_b1, freeu_b2, freeu_s1, freeu_s2)
+
+        p.sd_model.forge_objects.unet = unet
+
+        # Below codes will add some logs to the texts below the image outputs on UI.
+        # The extra_generation_params does not influence results.
+        p.extra_generation_params.update(dict(
+            freeu_enabled=freeu_enabled,
+            freeu_b1=freeu_b1,
+            freeu_b2=freeu_b2,
+            freeu_s1=freeu_s1,
+            freeu_s2=freeu_s2,
+        ))
+
+        return
+```