From 19373aee759be2f0868a69603c5d967e5e63e1c5 Mon Sep 17 00:00:00 2001
From: BVH <82035780+bvhari@users.noreply.github.com>
Date: Fri, 18 Apr 2025 00:54:33 +0530
Subject: [PATCH] Add FreSca node (#7631)

---
 comfy_extras/nodes_fresca.py | 102 +++++++++++++++++++++++++++++++++++
 nodes.py                     |   3 +-
 2 files changed, 104 insertions(+), 1 deletion(-)
 create mode 100644 comfy_extras/nodes_fresca.py

diff --git a/comfy_extras/nodes_fresca.py b/comfy_extras/nodes_fresca.py
new file mode 100644
index 00000000..b0b86f23
--- /dev/null
+++ b/comfy_extras/nodes_fresca.py
@@ -0,0 +1,102 @@
+# Code based on https://github.com/WikiChao/FreSca (MIT License)
+import torch
+import torch.fft as fft
+
+
+def Fourier_filter(x, scale_low=1.0, scale_high=1.5, freq_cutoff=20):
+    """
+    Apply frequency-dependent scaling to an image tensor using Fourier transforms.
+
+    Parameters:
+        x:           Input tensor of shape (B, C, H, W)
+        scale_low:   Scaling factor for low-frequency components (default: 1.0)
+        scale_high:  Scaling factor for high-frequency components (default: 1.5)
+        freq_cutoff: Number of frequency indices around center to consider as low-frequency (default: 20)
+
+    Returns:
+        x_filtered: Filtered version of x in spatial domain with frequency-specific scaling applied.
+    """
+    # Preserve input dtype and device
+    dtype, device = x.dtype, x.device
+
+    # Convert to float32 for FFT computations
+    x = x.to(torch.float32)
+
+    # 1) Apply FFT and shift low frequencies to center
+    x_freq = fft.fftn(x, dim=(-2, -1))
+    x_freq = fft.fftshift(x_freq, dim=(-2, -1))
+
+    # 2) Create a mask to scale frequencies differently
+    B, C, H, W = x_freq.shape
+    crow, ccol = H // 2, W // 2
+
+    # Initialize mask with high-frequency scaling factor
+    mask = torch.ones((B, C, H, W), device=device) * scale_high
+
+    # Apply low-frequency scaling factor to center region
+    mask[
+        ...,
+        crow - freq_cutoff : crow + freq_cutoff,
+        ccol - freq_cutoff : ccol + freq_cutoff,
+    ] = scale_low
+
+    # 3) Apply frequency-specific scaling
+    x_freq = x_freq * mask
+
+    # 4) Convert back to spatial domain
+    x_freq = fft.ifftshift(x_freq, dim=(-2, -1))
+    x_filtered = fft.ifftn(x_freq, dim=(-2, -1)).real
+
+    # 5) Restore original dtype
+    x_filtered = x_filtered.to(dtype)
+
+    return x_filtered
+
+
+class FreSca:
+    @classmethod
+    def INPUT_TYPES(s):
+        return {
+            "required": {
+                "model": ("MODEL",),
+                "scale_low": ("FLOAT", {"default": 1.0, "min": 0, "max": 10, "step": 0.01,
+                                        "tooltip": "Scaling factor for low-frequency components"}),
+                "scale_high": ("FLOAT", {"default": 1.25, "min": 0, "max": 10, "step": 0.01,
+                                        "tooltip": "Scaling factor for high-frequency components"}),
+                "freq_cutoff": ("INT", {"default": 20, "min": 1, "max": 100, "step": 1,
+                                        "tooltip": "Number of frequency indices around center to consider as low-frequency"}),
+            }
+        }
+    RETURN_TYPES = ("MODEL",)
+    FUNCTION = "patch"
+    CATEGORY = "_for_testing"
+    DESCRIPTION = "Applies frequency-dependent scaling to the guidance"
+    def patch(self, model, scale_low, scale_high, freq_cutoff):
+        def custom_cfg_function(args):
+            cond = args["conds_out"][0]
+            uncond = args["conds_out"][1]
+
+            guidance = cond - uncond
+            filtered_guidance = Fourier_filter(
+                guidance,
+                scale_low=scale_low,
+                scale_high=scale_high,
+                freq_cutoff=freq_cutoff,
+            )
+            filtered_cond = filtered_guidance + uncond
+
+            return [filtered_cond, uncond]
+
+        m = model.clone()
+        m.set_model_sampler_pre_cfg_function(custom_cfg_function)
+
+        return (m,)
+
+
+NODE_CLASS_MAPPINGS = {
+    "FreSca": FreSca,
+}
+
+NODE_DISPLAY_NAME_MAPPINGS = {
+    "FreSca": "FreSca",
+}
diff --git a/nodes.py b/nodes.py
index ae0a2e18..fce3dcb3 100644
--- a/nodes.py
+++ b/nodes.py
@@ -2281,7 +2281,8 @@ def init_builtin_extra_nodes():
         "nodes_primitive.py",
         "nodes_cfg.py",
         "nodes_optimalsteps.py",
-        "nodes_hidream.py"
+        "nodes_hidream.py",
+        "nodes_fresca.py",
     ]
 
     import_failed = []