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import numpy as np |
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import torch |
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from torchvision import transforms |
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import torch.nn.functional as F |
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from torch.autograd.variable import Variable |
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NORMALIZE_IMAGENET = transforms.Normalize(mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225]) |
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device = torch.device("cuda" if torch.cuda.is_available() else "cpu") |
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image_mean = torch.Tensor(NORMALIZE_IMAGENET.mean).view(-1, 1, 1).to(device) |
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image_std = torch.Tensor(NORMALIZE_IMAGENET.std).view(-1, 1, 1).to(device) |
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def normalize_img(x): |
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return (x.to(device) - image_mean) / image_std |
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def unnormalize_img(x): |
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return (x.to(device) * image_std) + image_mean |
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def round_pixel(x): |
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x_pixel = 255 * unnormalize_img(x) |
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y = torch.round(x_pixel).clamp(0, 255) |
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y = normalize_img(y/255.0) |
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return y |
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def project_linf(x, y, radius): |
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""" Clamp x-y so that Linf(x,y)<=radius """ |
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delta = x - y |
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delta = 255 * (delta * image_std) |
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delta = torch.clamp(delta, -radius, radius) |
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delta = (delta / 255.0) / image_std |
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return y + delta |
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def psnr_clip(x, y, target_psnr): |
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""" Clip x-y so that PSNR(x,y)=target_psnr """ |
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delta = x - y |
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delta = 255 * (delta * image_std) |
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psnr = 20*np.log10(255) - 10*torch.log10(torch.mean(delta**2)) |
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if psnr<target_psnr: |
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delta = (torch.sqrt(10**((psnr-target_psnr)/10))) * delta |
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psnr = 20*np.log10(255) - 10*torch.log10(torch.mean(delta**2)) |
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delta = (delta / 255.0) / image_std |
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return y + delta |
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def ssim_heatmap(img1, img2, window_size): |
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""" Compute the SSIM heatmap between 2 images """ |
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_1D_window = torch.Tensor( |
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[np.exp(-(x - window_size//2)**2/float(2*1.5**2)) for x in range(window_size)] |
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).to(device, non_blocking=True) |
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_1D_window = (_1D_window/_1D_window.sum()).unsqueeze(1) |
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_2D_window = _1D_window.mm(_1D_window.t()).float().unsqueeze(0).unsqueeze(0) |
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window = Variable(_2D_window.expand(3, 1, window_size, window_size).contiguous()) |
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mu1 = F.conv2d(img1, window, padding = window_size//2, groups = 3) |
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mu2 = F.conv2d(img2, window, padding = window_size//2, groups = 3) |
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mu1_sq = mu1.pow(2) |
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mu2_sq = mu2.pow(2) |
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mu1_mu2 = mu1*mu2 |
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sigma1_sq = F.conv2d(img1*img1, window, padding = window_size//2, groups = 3) - mu1_sq |
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sigma2_sq = F.conv2d(img2*img2, window, padding = window_size//2, groups = 3) - mu2_sq |
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sigma12 = F.conv2d(img1*img2, window, padding = window_size//2, groups = 3) - mu1_mu2 |
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C1 = 0.01**2 |
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C2 = 0.03**2 |
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ssim_map = ((2*mu1_mu2 + C1)*(2*sigma12 + C2))/((mu1_sq + mu2_sq + C1)*(sigma1_sq + sigma2_sq + C2)) |
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return ssim_map |
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def ssim_attenuation(x, y): |
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""" attenuate x-y using SSIM heatmap """ |
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delta = x - y |
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ssim_map = ssim_heatmap(x, y, window_size=17) |
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ssim_map = torch.sum(ssim_map, dim=1, keepdim=True) |
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ssim_map = torch.clamp_min(ssim_map,0) |
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delta = delta*ssim_map |
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return y + delta |
