128 lines
4.5 KiB
Python
128 lines
4.5 KiB
Python
import pydiffvg
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import torch
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import skimage
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import numpy as np
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# Use GPU if available
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pydiffvg.set_use_gpu(torch.cuda.is_available())
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canvas_width, canvas_height = 256, 256
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color = pydiffvg.LinearGradient(\
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begin = torch.tensor([50.0, 50.0]),
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end = torch.tensor([200.0, 200.0]),
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offsets = torch.tensor([0.0, 1.0]),
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stop_colors = torch.tensor([[0.2, 0.5, 0.7, 1.0],
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[0.7, 0.2, 0.5, 1.0]]))
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circle = pydiffvg.Circle(radius = torch.tensor(40.0),
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center = torch.tensor([128.0, 128.0]))
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shapes = [circle]
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circle_group = pydiffvg.ShapeGroup(shape_ids = torch.tensor([0]), fill_color = color)
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shape_groups = [circle_group]
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scene_args = pydiffvg.RenderFunction.serialize_scene(\
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canvas_width, canvas_height, shapes, shape_groups)
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render = pydiffvg.RenderFunction.apply
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img = render(256, # width
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256, # height
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2, # num_samples_x
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2, # num_samples_y
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0, # seed
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*scene_args)
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# The output image is in linear RGB space. Do Gamma correction before saving the image.
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pydiffvg.imwrite(img.cpu(), 'results/single_gradient/target.png', gamma=2.2)
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target = img.clone()
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# Move the circle to produce initial guess
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# normalize radius & center for easier learning rate
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radius_n = torch.tensor(20.0 / 256.0, requires_grad=True)
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center_n = torch.tensor([108.0 / 256.0, 138.0 / 256.0], requires_grad=True)
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begin_n = torch.tensor([100.0 / 256.0, 100.0 / 256.0], requires_grad=True)
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end_n = torch.tensor([150.0 / 256.0, 150.0 / 256.0], requires_grad=True)
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stop_colors = torch.tensor([[0.1, 0.9, 0.2, 1.0],
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[0.5, 0.3, 0.6, 1.0]], requires_grad=True)
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color.begin = begin_n * 256
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color.end = end_n * 256
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color.stop_colors = stop_colors
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circle.radius = radius_n * 256
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circle.center = center_n * 256
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circle_group.fill_color = color
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shapes = [circle]
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scene_args = pydiffvg.RenderFunction.serialize_scene(\
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canvas_width, canvas_height, shapes, shape_groups)
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img = render(256, # width
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256, # height
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2, # num_samples_x
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2, # num_samples_y
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1, # seed
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*scene_args)
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pydiffvg.imwrite(img.cpu(), 'results/single_gradient/init.png', gamma=2.2)
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# Optimize for radius & center
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optimizer = torch.optim.Adam([radius_n, center_n, begin_n, end_n, stop_colors], lr=1e-2)
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# Run 50 Adam iterations.
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for t in range(100):
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print('iteration:', t)
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optimizer.zero_grad()
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# Forward pass: render the image.
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color.begin = begin_n * 256
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color.end = end_n * 256
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color.stop_colors = stop_colors
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circle.radius = radius_n * 256
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circle.center = center_n * 256
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circle_group.fill_color = color
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scene_args = pydiffvg.RenderFunction.serialize_scene(\
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canvas_width, canvas_height, shapes, shape_groups)
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img = render(256, # width
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256, # height
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2, # num_samples_x
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2, # num_samples_y
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t+1, # seed
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*scene_args)
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# Save the intermediate render.
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pydiffvg.imwrite(img.cpu(), 'results/single_gradient/iter_{}.png'.format(t), gamma=2.2)
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# Compute the loss function. Here it is L2.
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loss = (img - target).pow(2).sum()
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print('loss:', loss.item())
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# Backpropagate the gradients.
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loss.backward()
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# Print the gradients
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print('radius.grad:', radius_n.grad)
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print('center.grad:', center_n.grad)
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print('begin.grad:', begin_n.grad)
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print('end.grad:', end_n.grad)
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print('stop_colors.grad:', stop_colors.grad)
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# Take a gradient descent step.
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optimizer.step()
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# Print the current params.
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print('radius:', circle.radius)
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print('center:', circle.center)
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print('begin:', begin_n)
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print('end:', end_n)
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print('stop_colors:', stop_colors)
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# Render the final result.
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color.begin = begin_n * 256
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color.end = end_n * 256
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color.stop_colors = stop_colors
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circle.radius = radius_n * 256
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circle.center = center_n * 256
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circle_group.fill_color = color
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scene_args = pydiffvg.RenderFunction.serialize_scene(\
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canvas_width, canvas_height, shapes, shape_groups)
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img = render(256, # width
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256, # height
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2, # num_samples_x
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2, # num_samples_y
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52, # seed
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*scene_args)
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# Save the images and differences.
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pydiffvg.imwrite(img.cpu(), 'results/single_gradient/final.png')
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# Convert the intermediate renderings to a video.
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from subprocess import call
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call(["ffmpeg", "-framerate", "24", "-i",
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"results/single_gradient/iter_%d.png", "-vb", "20M",
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"results/single_gradient/out.mp4"])
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