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Sean Lynch
2023-09-02 20:32:06 -04:00
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MIT License
Copyright (c) 2023 Sean Lynch
Copyright (c) 2022 the comfyui-optical-flow authors
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
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= About =
This package contains three nodes to help you compute optical flow
between pairs of images, usually adjacent frames in a video, visualize
the flow, and apply the flow to another image of the same dimensions.
Most of the code is from [Deforum](https://deforum.github.io/), so
this is released under the same license (MIT).
= Nodes =
== Compute optical flow ==
This node takes two images, prev and current, and computes the optical
flow between them using either the DIS (Dense Inverse Search) medium
or fine method, or Farneback. The images must have the same
dimensions.
== Apply optical flow ==
This node takes an image and applies an optical flow to it, so that
the motion matches the original image. This can be used for example to
improve consistency between video frames in a vid2vid workflow, by
applying the motion between the previous input frame and the current
one to the previous output frame before using it as input to a sampler.
== Visualize optical flow ==
This node takes an image and a flow and produces an image visualizing
the flow on top of the image. The image must be the same size as the
images used to compute the flow in the first place. It's up to you
whether you use the "prev", "current", or an image you intend to apply
the flow to.
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from .optical_flow import NODE_CLASS_MAPPINGS, NODE_DISPLAY_NAME_MAPPINGS
__all__ = ["NODE_CLASS_MAPPINGS", "NODE_DISPLAY_NAME_MAPPINGS"]
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import numpy as np
import cv2
import torch
def np2tensor(img_np: np.ndarray | list[np.ndarray]) -> torch.Tensor:
if isinstance(img_np, list):
return torch.cat([np2tensor(img) for img in img_np], dim=0)
return torch.from_numpy(img_np.astype(np.float32) / 255.0).unsqueeze(0)
def tensor2np(tensor: torch.Tensor) -> list[np.ndarray]:
batch_count = tensor.size(0) if len(tensor.shape) > 3 else 1
if batch_count > 1:
out = []
for i in range(batch_count):
out.extend(tensor2np(tensor[i]))
return out
return [np.clip(255.0 * tensor.cpu().numpy().squeeze(), 0, 255).astype(np.uint8)]
def remap(img, flow, border_mode = cv2.BORDER_REFLECT_101):
# copyMakeBorder doesn't support wrap, but supports replicate. Replaces wrap with reflect101.
if border_mode == cv2.BORDER_WRAP:
border_mode = cv2.BORDER_REFLECT_101
h, w = img.shape[:2]
displacement = int(h * 0.25), int(w * 0.25)
larger_img = cv2.copyMakeBorder(img, displacement[0], displacement[0], displacement[1], displacement[1], border_mode)
lh, lw = larger_img.shape[:2]
larger_flow = extend_flow(flow, lw, lh)
remapped_img = cv2.remap(larger_img, larger_flow, None, cv2.INTER_LINEAR, border_mode)
output_img = center_crop_image(remapped_img, w, h)
return output_img
def center_crop_image(img, w, h):
y, x, _ = img.shape
width_indent = int((x - w) / 2)
height_indent = int((y - h) / 2)
cropped_img = img[height_indent:y-height_indent, width_indent:x-width_indent]
return cropped_img
def extend_flow(flow, w, h):
# Get the shape of the original flow image
flow_h, flow_w = flow.shape[:2]
# Calculate the position of the image in the new image
x_offset = int((w - flow_w) / 2)
y_offset = int((h - flow_h) / 2)
# Generate the X and Y grids
x_grid, y_grid = np.meshgrid(np.arange(w), np.arange(h))
# Create the new flow image and set it to the X and Y grids
new_flow = np.dstack((x_grid, y_grid)).astype(np.float32)
# Shift the values of the original flow by the size of the border
flow[:,:,0] += x_offset
flow[:,:,1] += y_offset
# Overwrite the middle of the grid with the original flow
new_flow[y_offset:y_offset+flow_h, x_offset:x_offset+flow_w, :] = flow
# Return the extended image
return new_flow
def get_flow_from_images(i1, i2, method, prev_flow=None):
if method == "DIS Medium":
flow = get_flow_from_images_DIS(i1, i2, 'medium', prev_flow)
elif method == "DIS Fine":
flow = get_flow_from_images_DIS(i1, i2, 'fine', prev_flow)
elif method == "Farneback": # Farneback Normal:
flow = get_flow_from_images_Farneback(i1, i2, prev_flow)
else:
# if we reached this point, something went wrong. raise an error:
raise RuntimeError(f"Invald flow method name: '{method}'")
return flow
def get_flow_from_images_DIS(i1, i2, preset, prev_flow):
# DIS PRESETS CHART KEY: finest scale, grad desc its, patch size
# DIS_MEDIUM: 1, 25, 8 | DIS_FAST: 2, 16, 8 | DIS_ULTRAFAST: 2, 12, 8
if preset == 'medium': preset_code = cv2.DISOPTICAL_FLOW_PRESET_MEDIUM
elif preset == 'fast': preset_code = cv2.DISOPTICAL_FLOW_PRESET_FAST
elif preset == 'ultrafast': preset_code = cv2.DISOPTICAL_FLOW_PRESET_ULTRAFAST
elif preset in ['slow','fine']: preset_code = None
i1 = cv2.cvtColor(i1, cv2.COLOR_BGR2GRAY)
i2 = cv2.cvtColor(i2, cv2.COLOR_BGR2GRAY)
dis = cv2.DISOpticalFlow_create(preset_code)
# custom presets
if preset == 'slow':
dis.setGradientDescentIterations(192)
dis.setFinestScale(1)
dis.setPatchSize(8)
dis.setPatchStride(4)
if preset == 'fine':
dis.setGradientDescentIterations(192)
dis.setFinestScale(0)
dis.setPatchSize(8)
dis.setPatchStride(4)
return dis.calc(i1, i2, prev_flow)
def get_flow_from_images_Farneback(i1, i2, preset="normal", last_flow=None, pyr_scale = 0.5, levels = 3, winsize = 15, iterations = 3, poly_n = 5, poly_sigma = 1.2, flags = 0):
flags = cv2.OPTFLOW_FARNEBACK_GAUSSIAN # Specify the operation flags
pyr_scale = 0.5 # The image scale (<1) to build pyramids for each image
if preset == "fine":
levels = 13 # The number of pyramid layers, including the initial image
winsize = 77 # The averaging window size
iterations = 13 # The number of iterations at each pyramid level
poly_n = 15 # The size of the pixel neighborhood used to find polynomial expansion in each pixel
poly_sigma = 0.8 # The standard deviation of the Gaussian used to smooth derivatives used as a basis for the polynomial expansion
else: # "normal"
levels = 5 # The number of pyramid layers, including the initial image
winsize = 21 # The averaging window size
iterations = 5 # The number of iterations at each pyramid level
poly_n = 7 # The size of the pixel neighborhood used to find polynomial expansion in each pixel
poly_sigma = 1.2 # The standard deviation of the Gaussian used to smooth derivatives used as a basis for the polynomial expansion
i1 = cv2.cvtColor(i1, cv2.COLOR_BGR2GRAY)
i2 = cv2.cvtColor(i2, cv2.COLOR_BGR2GRAY)
flags = 0 # flags = cv2.OPTFLOW_USE_INITIAL_FLOW
flow = cv2.calcOpticalFlowFarneback(i1, i2, last_flow, pyr_scale, levels, winsize, iterations, poly_n, poly_sigma, flags)
return flow
def image_transform_optical_flow(img, flow, border_mode=cv2.BORDER_REPLICATE, flow_reverse=False):
if not flow_reverse:
flow = -flow
h, w = img.shape[:2]
flow[:, :, 0] += np.arange(w)
flow[:, :, 1] += np.arange(h)[:,np.newaxis]
return remap(img, flow, border_mode)
def draw_flow_lines_in_grid_in_color(img, flow, step=8, magnitude_multiplier=1, min_magnitude = 0, max_magnitude = 10000):
flow = flow * magnitude_multiplier
h, w = img.shape[:2]
y, x = np.mgrid[step/2:h:step, step/2:w:step].reshape(2,-1).astype(int)
fx, fy = flow[y,x].T
lines = np.vstack([x, y, x+fx, y+fy]).T.reshape(-1, 2, 2)
lines = np.int32(lines + 0.5)
vis = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
vis = cv2.cvtColor(vis, cv2.COLOR_GRAY2BGR)
mag, ang = cv2.cartToPolar(flow[...,0], flow[...,1])
hsv = np.zeros((flow.shape[0], flow.shape[1], 3), dtype=np.uint8)
hsv[...,0] = ang*180/np.pi/2
hsv[...,1] = 255
hsv[...,2] = cv2.normalize(mag, None, 0, 255, cv2.NORM_MINMAX)
bgr = cv2.cvtColor(hsv, cv2.COLOR_HSV2BGR)
vis = cv2.add(vis, bgr)
# Iterate through the lines
for (x1, y1), (x2, y2) in lines:
# Calculate the magnitude of the line
magnitude = np.sqrt((x2 - x1)**2 + (y2 - y1)**2)
# Only draw the line if it falls within the magnitude range
if min_magnitude <= magnitude <= max_magnitude:
b = int(bgr[y1, x1, 0])
g = int(bgr[y1, x1, 1])
r = int(bgr[y1, x1, 2])
color = (b, g, r)
cv2.arrowedLine(vis, (x1, y1), (x2, y2), color, thickness=1, tipLength=0.1)
return vis
def visualize_flow(flow_img, flow):
flow_img = cv2.cvtColor(flow_img, cv2.COLOR_RGB2GRAY)
flow_img = cv2.cvtColor(flow_img, cv2.COLOR_GRAY2BGR)
flow_img = draw_flow_lines_in_grid_in_color(flow_img, flow)
return cv2.cvtColor(flow_img, cv2.COLOR_BGR2RGB)
class ComputeOpticalFlow:
def __init__(self):
pass
@classmethod
def INPUT_TYPES(cls):
return {
"required": {
"prev": ("IMAGE",),
"current": ("IMAGE",),
"method": ([
"DIS Medium",
"DIS Fine",
"Farneback",
],),
},
}
RETURN_TYPES = ("OPTICAL_FLOW",)
FUNCTION = "compute_flow"
CATEGORY = "Optical flow"
def compute_flow(self, prev, current, method):
images = zip(tensor2np(prev), tensor2np(current))
return ([get_flow_from_images(im1, im2, method) for im1, im2 in images],)
class ApplyOpticalFlow:
def __init__(self):
pass
@classmethod
def INPUT_TYPES(cls):
return {
"required": {
"image": ("IMAGE",),
"flow": ("OPTICAL_FLOW",),
},
}
RETURN_TYPES = ("IMAGE",)
FUNCTION = "apply_flow"
CATEGORY = "Optical flow"
def apply_flow(self, image, flow):
ims = tensor2np(image)
out = [image_transform_optical_flow(im, f) for im, f in zip(ims, flow)]
return (np2tensor(out),)
class VisualizeOpticalFlow:
"""Visualize a flow as a set of arrows superimposed on the original image."""
@classmethod
def INPUT_TYPES(cls):
return {
"required": {
"image": ("IMAGE",),
"flow": ("OPTICAL_FLOW",),
},
}
RETURN_TYPES = ("IMAGE",)
FUNCTION = "visualize_flow"
CATEGORY = "Optical flow"
def visualize_flow(self, image, flow):
ifs = zip(tensor2np(image), flow)
out = [visualize_flow(img, flow) for img, flow in ifs]
return (np2tensor(out),)
# A dictionary that contains all nodes you want to export with their names
# NOTE: names should be globally unique
NODE_CLASS_MAPPINGS = {
"Compute optical flow": ComputeOpticalFlow,
"Apply optical flow": ApplyOpticalFlow,
"Visualize optical flow": VisualizeOpticalFlow,
}
# A dictionary that contains the friendly/humanly readable titles for the nodes
NODE_DISPLAY_NAME_MAPPINGS = {
"ComputeOpticalFlow": "Compute optical flow",
"ApplyOpticalFlow": "Apply optical flow",
"VisualizeOpticalFlow": "Visualize optical flow",
}