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import numpy as np
import torch
import torch.nn as nn
import torch.nn.functional as F
from kornia.geometry import warp_affine
def resize_n_crop(image, M, dsize=112):
# image: (b, c, h, w)
# M : (b, 2, 3)
return warp_affine(image, M, dsize=(dsize, dsize))
### perceptual level loss
class PerceptualLoss(nn.Module):
def __init__(self, recog_net, input_size=112):
super(PerceptualLoss, self).__init__()
self.recog_net = recog_net
self.preprocess = lambda x: 2 * x - 1
self.input_size = input_size
def forward(imageA, imageB, M):
"""
1 - cosine distance
Parameters:
imageA --torch.tensor (B, 3, H, W), range (0, 1) , RGB order
imageB --same as imageA
"""
imageA = self.preprocess(resize_n_crop(imageA, M, self.input_size))
imageB = self.preprocess(resize_n_crop(imageB, M, self.input_size))
# freeze bn
self.recog_net.eval()
id_featureA = F.normalize(self.recog_net(imageA), dim=-1, p=2)
id_featureB = F.normalize(self.recog_net(imageB), dim=-1, p=2)
cosine_d = torch.sum(id_featureA * id_featureB, dim=-1)
# assert torch.sum((cosine_d > 1).float()) == 0
return torch.sum(1 - cosine_d) / cosine_d.shape[0]
def perceptual_loss(id_featureA, id_featureB):
cosine_d = torch.sum(id_featureA * id_featureB, dim=-1)
# assert torch.sum((cosine_d > 1).float()) == 0
return torch.sum(1 - cosine_d) / cosine_d.shape[0]
### image level loss
def photo_loss(imageA, imageB, mask, eps=1e-6):
"""
l2 norm (with sqrt, to ensure backward stabililty, use eps, otherwise Nan may occur)
Parameters:
imageA --torch.tensor (B, 3, H, W), range (0, 1), RGB order
imageB --same as imageA
"""
loss = torch.sqrt(eps + torch.sum((imageA - imageB) ** 2, dim=1, keepdims=True)) * mask
loss = torch.sum(loss) / torch.max(torch.sum(mask), torch.tensor(1.0).to(mask.device))
return loss
def landmark_loss(predict_lm, gt_lm, weight=None):
"""
weighted mse loss
Parameters:
predict_lm --torch.tensor (B, 68, 2)
gt_lm --torch.tensor (B, 68, 2)
weight --numpy.array (1, 68)
"""
if not weight:
weight = np.ones([68])
weight[28:31] = 20
weight[-8:] = 20
weight = np.expand_dims(weight, 0)
weight = torch.tensor(weight).to(predict_lm.device)
loss = torch.sum((predict_lm - gt_lm) ** 2, dim=-1) * weight
loss = torch.sum(loss) / (predict_lm.shape[0] * predict_lm.shape[1])
return loss
### regulization
def reg_loss(coeffs_dict, opt=None):
"""
l2 norm without the sqrt, from yu's implementation (mse)
tf.nn.l2_loss https://www.tensorflow.org/api_docs/python/tf/nn/l2_loss
Parameters:
coeffs_dict -- a dict of torch.tensors , keys: id, exp, tex, angle, gamma, trans
"""
# coefficient regularization to ensure plausible 3d faces
if opt:
w_id, w_exp, w_tex = opt.w_id, opt.w_exp, opt.w_tex
else:
w_id, w_exp, w_tex = 1, 1, 1, 1
creg_loss = (
w_id * torch.sum(coeffs_dict["id"] ** 2)
+ w_exp * torch.sum(coeffs_dict["exp"] ** 2)
+ w_tex * torch.sum(coeffs_dict["tex"] ** 2)
)
creg_loss = creg_loss / coeffs_dict["id"].shape[0]
# gamma regularization to ensure a nearly-monochromatic light
gamma = coeffs_dict["gamma"].reshape([-1, 3, 9])
gamma_mean = torch.mean(gamma, dim=1, keepdims=True)
gamma_loss = torch.mean((gamma - gamma_mean) ** 2)
return creg_loss, gamma_loss
def reflectance_loss(texture, mask):
"""
minimize texture variance (mse), albedo regularization to ensure an uniform skin albedo
Parameters:
texture --torch.tensor, (B, N, 3)
mask --torch.tensor, (N), 1 or 0
"""
mask = mask.reshape([1, mask.shape[0], 1])
texture_mean = torch.sum(mask * texture, dim=1, keepdims=True) / torch.sum(mask)
loss = torch.sum(((texture - texture_mean) * mask) ** 2) / (texture.shape[0] * torch.sum(mask))
return loss
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