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barisgecer avatar barisgecer commented on July 28, 2024 2

Hi Rodney,

Thanks for your interest in our work.

That is actually an excellent question. That part took a good amount of time in the project.

During the alignment of each image, I had to dig into stylegan alignment pipeline, extract transformation parameters, and apply them to the projected face model S'_i. You can have a sneak peek at the part that I am doing that below. I believe it will be more clear when I release the full code.

Hope that helps,
Baris


from menpo.shape import TriMesh, TexturedTriMesh, ColouredTriMesh
from menpo.image import Image
from image_rasterization import *
import numpy as np
import numpy as np
import scipy.ndimage
import os
import PIL.Image
import pickle

def create_perspective_transform_matrix(src, dst):
    """ Creates a perspective transformation matrix which transforms points
        in quadrilateral ``src`` to the corresponding points on quadrilateral
        ``dst``.

        Will raise a ``np.linalg.LinAlgError`` on invalid input.
        """
    # See:
    # * http://xenia.media.mit.edu/~cwren/interpolator/
    # * http://stackoverflow.com/a/14178717/71522
    in_matrix = []
    for (x, y), (X, Y) in zip(src, dst):
        in_matrix.extend([
            [x, y, 1, 0, 0, 0, -X * x, -X * y],
            [0, 0, 0, x, y, 1, -Y * x, -Y * y],
        ])

    A = np.matrix(in_matrix, dtype=np.float)
    B = np.array(dst).reshape(8)
    af = np.dot(np.linalg.inv(A.T * A) * A.T, B)
    return np.append(np.array(af).reshape(8), 1).reshape((3, 3))


def create_perspective_transform(src, dst, round=False, splat_args=False):
    """ Returns a function which will transform points in quadrilateral
        ``src`` to the corresponding points on quadrilateral ``dst``::

            >>> transform = create_perspective_transform(
            ...     [(0, 0), (10, 0), (10, 10), (0, 10)],
            ...     [(50, 50), (100, 50), (100, 100), (50, 100)],
            ... )
            >>> transform((5, 5))
            (74.99999999999639, 74.999999999999957)

        If ``round`` is ``True`` then points will be rounded to the nearest
        integer and integer values will be returned.

            >>> transform = create_perspective_transform(
            ...     [(0, 0), (10, 0), (10, 10), (0, 10)],
            ...     [(50, 50), (100, 50), (100, 100), (50, 100)],
            ...     round=True,
            ... )
            >>> transform((5, 5))
            (75, 75)

        If ``splat_args`` is ``True`` the function will accept two arguments
        instead of a tuple.

            >>> transform = create_perspective_transform(
            ...     [(0, 0), (10, 0), (10, 10), (0, 10)],
            ...     [(50, 50), (100, 50), (100, 100), (50, 100)],
            ...     splat_args=True,
            ... )
            >>> transform(5, 5)
            (74.99999999999639, 74.999999999999957)

        If the input values yield an invalid transformation matrix an identity
        function will be returned and the ``error`` attribute will be set to a
        description of the error::

            >>> tranform = create_perspective_transform(
            ...     np.zeros((4, 2)),
            ...     np.zeros((4, 2)),
            ... )
            >>> transform((5, 5))
            (5.0, 5.0)
            >>> transform.error
            'invalid input quads (...): Singular matrix
        """
    try:
        transform_matrix = create_perspective_transform_matrix(src, dst)
        error = None
    except np.linalg.LinAlgError as e:
        transform_matrix = np.identity(3, dtype=np.float)
        error = "invalid input quads (%s and %s): %s" %(src, dst, e)
        error = error.replace("\n", "")

    to_eval = "def perspective_transform(%s):\n" %(
        splat_args and "*pt" or "pt",
    )
    to_eval += "  res = np.dot(transform_matrix, ((pt[0], ), (pt[1], ), (1, )))\n"
    to_eval += "  res = res / res[2]\n"
    if round:
        to_eval += "  return (int(round(res[0][0])), int(round(res[1][0])))\n"
    else:
        to_eval += "  return (res[0][0], res[1][0])\n"
    locals = {
        "transform_matrix": transform_matrix,
    }
    locals.update(globals())
    exec(to_eval,locals,locals)
    res = locals["perspective_transform"]
    res.matrix = transform_matrix
    res.error = error
    return res


def align_mesh2stylegan(temp_tcoords, transformation_params):
    temp_tcoords = temp_tcoords.copy()
    temp_tcoords[:, 0] = temp_tcoords[:, 0] - transformation_params['crop'][1]
    temp_tcoords[:, 1] = temp_tcoords[:, 1] - transformation_params['crop'][0]

    temp_tcoords[:, 0] = temp_tcoords[:, 0] + transformation_params['pad'][1]
    temp_tcoords[:, 1] = temp_tcoords[:, 1] + transformation_params['pad'][0]

    h, w = (4096, 4096)  # transformation_params['new_size']
    transform = create_perspective_transform(
        transformation_params['quad'],
        [(0, 0), (0, h), (h, w), (w, 0)],
        splat_args=True,
    )
    for i in range(len(temp_tcoords)):
        temp_tcoords[i, 1], temp_tcoords[i, 0] = transform(temp_tcoords[i, 1], temp_tcoords[i, 0])

    new_tcoords = temp_tcoords[:, ::-1] / (h, w)  # transformation_params['new_size']
    new_tcoords[:, 1] = 1 - new_tcoords[:, 1]
    return new_tcoords

def align_im2stylegan(src_im, src_mask, face_landmarks, output_size=1024, transform_size=4096,
                    enable_padding=True, x_scale=1, y_scale=1, em_scale=0.1, alpha=False):
        # Align function from FFHQ dataset pre-processing step
        # https://github.com/NVlabs/ffhq-dataset/blob/master/download_ffhq.py

        lm = np.array(face_landmarks)
        lm_chin = lm[0: 17]  # left-right
        lm_eyebrow_left = lm[17: 22]  # left-right
        lm_eyebrow_right = lm[22: 27]  # left-right
        lm_nose = lm[27: 31]  # top-down
        lm_nostrils = lm[31: 36]  # top-down
        lm_eye_left = lm[36: 42]  # left-clockwise
        lm_eye_right = lm[42: 48]  # left-clockwise
        lm_mouth_outer = lm[48: 60]  # left-clockwise
        lm_mouth_inner = lm[60: 68]  # left-clockwise

        # Calculate auxiliary vectors.
        eye_left = np.mean(lm_eye_left, axis=0)
        eye_right = np.mean(lm_eye_right, axis=0)
        eye_avg = (eye_left + eye_right) * 0.5
        eye_to_eye = eye_right - eye_left
        mouth_left = lm_mouth_outer[0]
        mouth_right = lm_mouth_outer[6]
        mouth_avg = (mouth_left + mouth_right) * 0.5
        eye_to_mouth = mouth_avg - eye_avg

        # Choose oriented crop rectangle.
        x = eye_to_eye - np.flipud(eye_to_mouth) * [-1, 1]
        x /= np.hypot(*x)
        x *= max(np.hypot(*eye_to_eye) * 2.0, np.hypot(*eye_to_mouth) * 1.8)
        x *= x_scale
        y = np.flipud(x) * [-y_scale, y_scale]
        c = eye_avg + eye_to_mouth * em_scale
        quad = np.stack([c - x - y, c - x + y, c + x + y, c + x - y])
        qsize = np.hypot(*x) * 2
        rsize = None

        img = src_im.convert('RGBA').convert('RGB')

        img_mask = src_mask.convert('L')

        img.putalpha(img_mask)

        # Shrink.
        shrink = int(np.floor(qsize / output_size * 0.5))
        if shrink > 1:
            rsize = (int(np.rint(float(img.size[0]) / shrink)), int(np.rint(float(img.size[1]) / shrink)))
            img = img.resize(rsize, PIL.Image.ANTIALIAS)
            quad /= shrink
            qsize /= shrink

        # Crop.
        border = max(int(np.rint(qsize * 0.1)), 3)
        crop = (int(np.floor(min(quad[:, 0]))), int(np.floor(min(quad[:, 1]))), int(np.ceil(max(quad[:, 0]))),
                int(np.ceil(max(quad[:, 1]))))
        crop = (max(crop[0] - border, 0), max(crop[1] - border, 0), min(crop[2] + border, img.size[0]),
                min(crop[3] + border, img.size[1]))
        if crop[2] - crop[0] < img.size[0] or crop[3] - crop[1] < img.size[1]:
            img = img.crop(crop)
            quad -= crop[0:2]

        # Pad.
        pad = (int(np.floor(min(quad[:, 0]))), int(np.floor(min(quad[:, 1]))), int(np.ceil(max(quad[:, 0]))),
               int(np.ceil(max(quad[:, 1]))))
        pad = (max(-pad[0] + border, 0), max(-pad[1] + border, 0), max(pad[2] - img.size[0] + border, 0),
               max(pad[3] - img.size[1] + border, 0))
        if enable_padding and max(pad) > border - 4:
            pad = np.maximum(pad, int(np.rint(qsize * 0.3)))
            img = np.pad(np.float32(img), ((pad[1], pad[3]), (pad[0], pad[2]), (0, 0)), 'constant')
            h, w, _ = img.shape
            y, x, _ = np.ogrid[:h, :w, :1]
            mask = np.maximum(1.0 - np.minimum(np.float32(x) / pad[0], np.float32(w - 1 - x) / pad[2]),
                              1.0 - np.minimum(np.float32(y) / pad[1], np.float32(h - 1 - y) / pad[3]))
            blur = qsize * 0.02
            img += (scipy.ndimage.gaussian_filter(img, [blur, blur, 0]) - img) * np.clip(mask * 3.0 + 1.0, 0.0, 1.0)
            img += (np.median(img, axis=(0, 1)) - img) * np.clip(mask, 0.0, 1.0)
            img = np.uint8(np.clip(np.rint(img), 0, 255))
            if alpha:
                mask = 1 - np.clip(3.0 * mask, 0.0, 1.0)
                mask = np.uint8(np.clip(np.rint(mask * 255), 0, 255))
                img = np.concatenate((img, mask), axis=2)
                img = PIL.Image.fromarray(img, 'RGBA')
            else:
                img = PIL.Image.fromarray(img, 'RGBA')
            quad += pad[:2]

        # Transform.
        aligned_mask = PIL.Image.fromarray(np.uint8(img)[:, :, 3])
        img = PIL.Image.fromarray(np.uint8(img)[:, :, :3])

        img = img.transform((transform_size, transform_size), PIL.Image.QUAD, (quad + 0.5).flatten(),
                            PIL.Image.BILINEAR)
        aligned_mask = aligned_mask.transform((transform_size, transform_size), PIL.Image.QUAD, (quad + 0.5).flatten(),
                                              PIL.Image.BILINEAR)
        if output_size < transform_size:
            img = img.resize((output_size, output_size), PIL.Image.ANTIALIAS)
            aligned_mask = aligned_mask.resize((output_size, output_size), PIL.Image.ANTIALIAS)

        transformation_params = {
            'rsize': rsize,
            'crop': crop,
            'pad': pad,
            'quad': quad + 0.5,
            'new_size': (output_size, output_size)
        }
        # Save aligned image.
        return img, aligned_mask, transformation_params



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RodneyPerhaps avatar RodneyPerhaps commented on July 28, 2024

Thank you, Baris! This helped a lot!

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RodneyPerhaps avatar RodneyPerhaps commented on July 28, 2024

Hi, Baris! It seems that converting I_i to PIL image in your code will break the back-propagation. I just wonder how did you make the alignment process differentiable in the training of the whole network? Did you write a custom back-propagation code for the alignment process?
BTW, I am sorry to reopen this issue...

from ostec.

barisgecer avatar barisgecer commented on July 28, 2024

Hi Rodney, I am not converting the generated image to PIL.Image. What you see in the code is the input image (target image). So the generated image from StyleGAN is directly given to the loss functions and networks to keep it differentiable.

from ostec.

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