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"""This script contains the image preprocessing code for Deep3DFaceRecon_pytorch
"""
import numpy as np
from scipy.io import loadmat
from PIL import Image
import cv2
import os
from skimage import transform as trans
import torch
import warnings
warnings.filterwarnings("ignore", category=np.VisibleDeprecationWarning)
warnings.filterwarnings("ignore", category=FutureWarning)
# calculating least square problem for image alignment
def POS(xp, x):
npts = xp.shape[1]
A = np.zeros([2*npts, 8])
A[0:2*npts-1:2, 0:3] = x.transpose()
A[0:2*npts-1:2, 3] = 1
A[1:2*npts:2, 4:7] = x.transpose()
A[1:2*npts:2, 7] = 1
b = np.reshape(xp.transpose(), [2*npts, 1])
k, _, _, _ = np.linalg.lstsq(A, b)
R1 = k[0:3]
R2 = k[4:7]
sTx = k[3]
sTy = k[7]
s = (np.linalg.norm(R1) + np.linalg.norm(R2))/2
t = np.stack([sTx, sTy], axis=0)
return t, s
# resize and crop images for face reconstruction
def resize_n_crop_img(img, lm, t, s, target_size=224., mask=None):
w0, h0 = img.size
w = (w0*s).astype(np.int32)
h = (h0*s).astype(np.int32)
left = (w/2 - target_size/2 + float((t[0] - w0/2)*s)).astype(np.int32)
right = left + target_size
up = (h/2 - target_size/2 + float((h0/2 - t[1])*s)).astype(np.int32)
below = up + target_size
img = img.resize((w, h), resample=Image.BICUBIC)
img = img.crop((left, up, right, below))
if mask is not None:
mask = mask.resize((w, h), resample=Image.BICUBIC)
mask = mask.crop((left, up, right, below))
lm = np.stack([lm[:, 0] - t[0] + w0/2, lm[:, 1] -
t[1] + h0/2], axis=1)*s
lm = lm - np.reshape(
np.array([(w/2 - target_size/2), (h/2-target_size/2)]), [1, 2])
return img, lm, mask
# utils for face reconstruction
def extract_5p(lm):
lm_idx = np.array([31, 37, 40, 43, 46, 49, 55]) - 1
lm5p = np.stack([lm[lm_idx[0], :], np.mean(lm[lm_idx[[1, 2]], :], 0), np.mean(
lm[lm_idx[[3, 4]], :], 0), lm[lm_idx[5], :], lm[lm_idx[6], :]], axis=0)
lm5p = lm5p[[1, 2, 0, 3, 4], :]
return lm5p
# utils for face reconstruction
def align_img(img, lm, lm3D, mask=None, target_size=224., rescale_factor=102.):
"""
Return:
transparams --numpy.array (raw_W, raw_H, scale, tx, ty)
img_new --PIL.Image (target_size, target_size, 3)
lm_new --numpy.array (68, 2), y direction is opposite to v direction
mask_new --PIL.Image (target_size, target_size)
Parameters:
img --PIL.Image (raw_H, raw_W, 3)
lm --numpy.array (68, 2), y direction is opposite to v direction
lm3D --numpy.array (5, 3)
mask --PIL.Image (raw_H, raw_W, 3)
"""
w0, h0 = img.size
if lm.shape[0] != 5:
lm5p = extract_5p(lm)
else:
lm5p = lm
# calculate translation and scale factors using 5 facial landmarks and standard landmarks of a 3D face
t, s = POS(lm5p.transpose(), lm3D.transpose())
s = rescale_factor/s
# processing the image
img_new, lm_new, mask_new = resize_n_crop_img(img, lm, t, s, target_size=target_size, mask=mask)
trans_params = np.array([w0, h0, s, t[0], t[1]])
return trans_params, img_new, lm_new, mask_new
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