dp2/detection/box_utils_fdf.py

"""
The FDF dataset expands bound boxes differently from what is used for CSE.
"""

import numpy as np


def quadratic_bounding_box(x0, y0, width, height, imshape):
    # We assume that we can create a image that is quadratic without
    # minimizing any of the sides
    assert width <= min(imshape[:2])
    assert height <= min(imshape[:2])
    min_side = min(height, width)
    if height != width:
        side_diff = abs(height - width)
        # Want to extend the shortest side
        if min_side == height:
            # Vertical side
            height += side_diff
            if height > imshape[0]:
                # Take full frame, and shrink width
                y0 = 0
                height = imshape[0]

                side_diff = abs(height - width)
                width -= side_diff
                x0 += side_diff // 2
            else:
                y0 -= side_diff // 2
                y0 = max(0, y0)
        else:
            # Horizontal side
            width += side_diff
            if width > imshape[1]:
                # Take full frame width, and shrink height
                x0 = 0
                width = imshape[1]

                side_diff = abs(height - width)
                height -= side_diff
                y0 += side_diff // 2
            else:
                x0 -= side_diff // 2
                x0 = max(0, x0)
        # Check that bbox goes outside image
        x1 = x0 + width
        y1 = y0 + height
        if imshape[1] < x1:
            diff = x1 - imshape[1]
            x0 -= diff
        if imshape[0] < y1:
            diff = y1 - imshape[0]
            y0 -= diff
    assert x0 >= 0, "Bounding box outside image."
    assert y0 >= 0, "Bounding box outside image."
    assert x0 + width <= imshape[1], "Bounding box outside image."
    assert y0 + height <= imshape[0], "Bounding box outside image."
    return x0, y0, width, height


def expand_bounding_box(bbox, percentage, imshape):
    orig_bbox = bbox.copy()
    x0, y0, x1, y1 = bbox
    width = x1 - x0
    height = y1 - y0
    x0, y0, width, height = quadratic_bounding_box(
        x0, y0, width, height, imshape)
    expanding_factor = int(max(height, width) * percentage)

    possible_max_expansion = [(imshape[0] - width) // 2,
                              (imshape[1] - height) // 2,
                              expanding_factor]

    expanding_factor = min(possible_max_expansion)
    # Expand height

    if expanding_factor > 0:

        y0 = y0 - expanding_factor
        y0 = max(0, y0)

        height += expanding_factor * 2
        if height > imshape[0]:
            y0 -= (imshape[0] - height)
            height = imshape[0]

        if height + y0 > imshape[0]:
            y0 -= (height + y0 - imshape[0])

        # Expand width
        x0 = x0 - expanding_factor
        x0 = max(0, x0)

        width += expanding_factor * 2
        if width > imshape[1]:
            x0 -= (imshape[1] - width)
            width = imshape[1]

        if width + x0 > imshape[1]:
            x0 -= (width + x0 - imshape[1])
    y1 = y0 + height
    x1 = x0 + width
    assert y0 >= 0, "Y0 is minus"
    assert height <= imshape[0], "Height is larger than image."
    assert x0 + width <= imshape[1]
    assert y0 + height <= imshape[0]
    assert width == height, "HEIGHT IS NOT EQUAL WIDTH!!"
    assert x0 >= 0, "Y0 is minus"
    assert width <= imshape[1], "Height is larger than image."
    # Check that original bbox is within new
    x0_o, y0_o, x1_o, y1_o = orig_bbox
    assert x0 <= x0_o, f"New bbox is outisde of original. O:{x0_o}, N: {x0}"
    assert x1 >= x1_o, f"New bbox is outisde of original. O:{x1_o}, N: {x1}"
    assert y0 <= y0_o, f"New bbox is outisde of original. O:{y0_o}, N: {y0}"
    assert y1 >= y1_o, f"New bbox is outisde of original. O:{y1_o}, N: {y1}"

    x0, y0, width, height = [int(_) for _ in [x0, y0, width, height]]
    x1 = x0 + width
    y1 = y0 + height
    return np.array([x0, y0, x1, y1])


def is_keypoint_within_bbox(x0, y0, x1, y1, keypoint):
    keypoint = keypoint[:, :3]  # only nose + eyes are relevant
    kp_X = keypoint[0, :]
    kp_Y = keypoint[1, :]
    within_X = np.all(kp_X >= x0) and np.all(kp_X <= x1)
    within_Y = np.all(kp_Y >= y0) and np.all(kp_Y <= y1)
    return within_X and within_Y


def expand_bbox_simple(bbox, percentage):
    x0, y0, x1, y1 = bbox.astype(float)
    width = x1 - x0
    height = y1 - y0
    x_c = int(x0) + width // 2
    y_c = int(y0) + height // 2
    avg_size = max(width, height)
    new_width = avg_size * (1 + percentage)
    x0 = x_c - new_width // 2
    y0 = y_c - new_width // 2
    x1 = x_c + new_width // 2
    y1 = y_c + new_width // 2
    return np.array([x0, y0, x1, y1]).astype(int)


def pad_image(im, bbox, pad_value):
    x0, y0, x1, y1 = bbox
    if x0 < 0:
        pad_im = np.zeros((im.shape[0], abs(x0), im.shape[2]),
                          dtype=np.uint8) + pad_value
        im = np.concatenate((pad_im, im), axis=1)
        x1 += abs(x0)
        x0 = 0
    if y0 < 0:
        pad_im = np.zeros((abs(y0), im.shape[1], im.shape[2]),
                          dtype=np.uint8) + pad_value
        im = np.concatenate((pad_im, im), axis=0)
        y1 += abs(y0)
        y0 = 0
    if x1 >= im.shape[1]:
        pad_im = np.zeros(
            (im.shape[0], x1 - im.shape[1] + 1, im.shape[2]),
            dtype=np.uint8) + pad_value
        im = np.concatenate((im, pad_im), axis=1)
    if y1 >= im.shape[0]:
        pad_im = np.zeros(
            (y1 - im.shape[0] + 1, im.shape[1], im.shape[2]),
            dtype=np.uint8) + pad_value
        im = np.concatenate((im, pad_im), axis=0)
    return im[y0:y1, x0:x1]


def clip_box(bbox, im):
    bbox[0] = max(0, bbox[0])
    bbox[1] = max(0, bbox[1])
    bbox[2] = min(im.shape[1] - 1, bbox[2])
    bbox[3] = min(im.shape[0] - 1, bbox[3])
    return bbox


def cut_face(im, bbox, simple_expand=False, pad_value=0, pad_im=True):
    outside_im = (bbox < 0).any() or bbox[2] > im.shape[1] or bbox[3] > im.shape[0]
    if simple_expand or (outside_im and pad_im):
        return pad_image(im, bbox, pad_value)
    bbox = clip_box(bbox, im)
    x0, y0, x1, y1 = bbox
    return im[y0:y1, x0:x1]


def expand_bbox(
        bbox_ltrb, imshape, simple_expand, default_to_simple=False,
        expansion_factor=0.35):
    assert bbox_ltrb.shape == (4,), f"BBox shape was: {bbox_ltrb.shape}"
    bbox = bbox_ltrb.astype(float)
    # FDF256 uses simple expand with ratio 0.4
    if simple_expand:
        return expand_bbox_simple(bbox, 0.4)
    try:
        return expand_bounding_box(bbox, expansion_factor, imshape)
    except AssertionError:
        return expand_bbox_simple(bbox, expansion_factor * 2)