ABINet-OCR / transforms.py
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import math
import numbers
import random
import cv2
import numpy as np
from PIL import Image
from torchvision import transforms
from torchvision.transforms import Compose
def sample_asym(magnitude, size=None):
return np.random.beta(1, 4, size) * magnitude
def sample_sym(magnitude, size=None):
return (np.random.beta(4, 4, size=size) - 0.5) * 2 * magnitude
def sample_uniform(low, high, size=None):
return np.random.uniform(low, high, size=size)
def get_interpolation(type='random'):
if type == 'random':
choice = [cv2.INTER_NEAREST, cv2.INTER_LINEAR, cv2.INTER_CUBIC, cv2.INTER_AREA]
interpolation = choice[random.randint(0, len(choice)-1)]
elif type == 'nearest': interpolation = cv2.INTER_NEAREST
elif type == 'linear': interpolation = cv2.INTER_LINEAR
elif type == 'cubic': interpolation = cv2.INTER_CUBIC
elif type == 'area': interpolation = cv2.INTER_AREA
else: raise TypeError('Interpolation types only nearest, linear, cubic, area are supported!')
return interpolation
class CVRandomRotation(object):
def __init__(self, degrees=15):
assert isinstance(degrees, numbers.Number), "degree should be a single number."
assert degrees >= 0, "degree must be positive."
self.degrees = degrees
@staticmethod
def get_params(degrees):
return sample_sym(degrees)
def __call__(self, img):
angle = self.get_params(self.degrees)
src_h, src_w = img.shape[:2]
M = cv2.getRotationMatrix2D(center=(src_w/2, src_h/2), angle=angle, scale=1.0)
abs_cos, abs_sin = abs(M[0,0]), abs(M[0,1])
dst_w = int(src_h * abs_sin + src_w * abs_cos)
dst_h = int(src_h * abs_cos + src_w * abs_sin)
M[0, 2] += (dst_w - src_w)/2
M[1, 2] += (dst_h - src_h)/2
flags = get_interpolation()
return cv2.warpAffine(img, M, (dst_w, dst_h), flags=flags, borderMode=cv2.BORDER_REPLICATE)
class CVRandomAffine(object):
def __init__(self, degrees, translate=None, scale=None, shear=None):
assert isinstance(degrees, numbers.Number), "degree should be a single number."
assert degrees >= 0, "degree must be positive."
self.degrees = degrees
if translate is not None:
assert isinstance(translate, (tuple, list)) and len(translate) == 2, \
"translate should be a list or tuple and it must be of length 2."
for t in translate:
if not (0.0 <= t <= 1.0):
raise ValueError("translation values should be between 0 and 1")
self.translate = translate
if scale is not None:
assert isinstance(scale, (tuple, list)) and len(scale) == 2, \
"scale should be a list or tuple and it must be of length 2."
for s in scale:
if s <= 0:
raise ValueError("scale values should be positive")
self.scale = scale
if shear is not None:
if isinstance(shear, numbers.Number):
if shear < 0:
raise ValueError("If shear is a single number, it must be positive.")
self.shear = [shear]
else:
assert isinstance(shear, (tuple, list)) and (len(shear) == 2), \
"shear should be a list or tuple and it must be of length 2."
self.shear = shear
else:
self.shear = shear
def _get_inverse_affine_matrix(self, center, angle, translate, scale, shear):
# https://github.com/pytorch/vision/blob/v0.4.0/torchvision/transforms/functional.py#L717
from numpy import sin, cos, tan
if isinstance(shear, numbers.Number):
shear = [shear, 0]
if not isinstance(shear, (tuple, list)) and len(shear) == 2:
raise ValueError(
"Shear should be a single value or a tuple/list containing " +
"two values. Got {}".format(shear))
rot = math.radians(angle)
sx, sy = [math.radians(s) for s in shear]
cx, cy = center
tx, ty = translate
# RSS without scaling
a = cos(rot - sy) / cos(sy)
b = -cos(rot - sy) * tan(sx) / cos(sy) - sin(rot)
c = sin(rot - sy) / cos(sy)
d = -sin(rot - sy) * tan(sx) / cos(sy) + cos(rot)
# Inverted rotation matrix with scale and shear
# det([[a, b], [c, d]]) == 1, since det(rotation) = 1 and det(shear) = 1
M = [d, -b, 0,
-c, a, 0]
M = [x / scale for x in M]
# Apply inverse of translation and of center translation: RSS^-1 * C^-1 * T^-1
M[2] += M[0] * (-cx - tx) + M[1] * (-cy - ty)
M[5] += M[3] * (-cx - tx) + M[4] * (-cy - ty)
# Apply center translation: C * RSS^-1 * C^-1 * T^-1
M[2] += cx
M[5] += cy
return M
@staticmethod
def get_params(degrees, translate, scale_ranges, shears, height):
angle = sample_sym(degrees)
if translate is not None:
max_dx = translate[0] * height
max_dy = translate[1] * height
translations = (np.round(sample_sym(max_dx)), np.round(sample_sym(max_dy)))
else:
translations = (0, 0)
if scale_ranges is not None:
scale = sample_uniform(scale_ranges[0], scale_ranges[1])
else:
scale = 1.0
if shears is not None:
if len(shears) == 1:
shear = [sample_sym(shears[0]), 0.]
elif len(shears) == 2:
shear = [sample_sym(shears[0]), sample_sym(shears[1])]
else:
shear = 0.0
return angle, translations, scale, shear
def __call__(self, img):
src_h, src_w = img.shape[:2]
angle, translate, scale, shear = self.get_params(
self.degrees, self.translate, self.scale, self.shear, src_h)
M = self._get_inverse_affine_matrix((src_w/2, src_h/2), angle, (0, 0), scale, shear)
M = np.array(M).reshape(2,3)
startpoints = [(0, 0), (src_w - 1, 0), (src_w - 1, src_h - 1), (0, src_h - 1)]
project = lambda x, y, a, b, c: int(a*x + b*y + c)
endpoints = [(project(x, y, *M[0]), project(x, y, *M[1])) for x, y in startpoints]
rect = cv2.minAreaRect(np.array(endpoints))
bbox = cv2.boxPoints(rect).astype(dtype=np.int)
max_x, max_y = bbox[:, 0].max(), bbox[:, 1].max()
min_x, min_y = bbox[:, 0].min(), bbox[:, 1].min()
dst_w = int(max_x - min_x)
dst_h = int(max_y - min_y)
M[0, 2] += (dst_w - src_w) / 2
M[1, 2] += (dst_h - src_h) / 2
# add translate
dst_w += int(abs(translate[0]))
dst_h += int(abs(translate[1]))
if translate[0] < 0: M[0, 2] += abs(translate[0])
if translate[1] < 0: M[1, 2] += abs(translate[1])
flags = get_interpolation()
return cv2.warpAffine(img, M, (dst_w , dst_h), flags=flags, borderMode=cv2.BORDER_REPLICATE)
class CVRandomPerspective(object):
def __init__(self, distortion=0.5):
self.distortion = distortion
def get_params(self, width, height, distortion):
offset_h = sample_asym(distortion * height / 2, size=4).astype(dtype=np.int)
offset_w = sample_asym(distortion * width / 2, size=4).astype(dtype=np.int)
topleft = ( offset_w[0], offset_h[0])
topright = (width - 1 - offset_w[1], offset_h[1])
botright = (width - 1 - offset_w[2], height - 1 - offset_h[2])
botleft = ( offset_w[3], height - 1 - offset_h[3])
startpoints = [(0, 0), (width - 1, 0), (width - 1, height - 1), (0, height - 1)]
endpoints = [topleft, topright, botright, botleft]
return np.array(startpoints, dtype=np.float32), np.array(endpoints, dtype=np.float32)
def __call__(self, img):
height, width = img.shape[:2]
startpoints, endpoints = self.get_params(width, height, self.distortion)
M = cv2.getPerspectiveTransform(startpoints, endpoints)
# TODO: more robust way to crop image
rect = cv2.minAreaRect(endpoints)
bbox = cv2.boxPoints(rect).astype(dtype=np.int)
max_x, max_y = bbox[:, 0].max(), bbox[:, 1].max()
min_x, min_y = bbox[:, 0].min(), bbox[:, 1].min()
min_x, min_y = max(min_x, 0), max(min_y, 0)
flags = get_interpolation()
img = cv2.warpPerspective(img, M, (max_x, max_y), flags=flags, borderMode=cv2.BORDER_REPLICATE)
img = img[min_y:, min_x:]
return img
class CVRescale(object):
def __init__(self, factor=4, base_size=(128, 512)):
""" Define image scales using gaussian pyramid and rescale image to target scale.
Args:
factor: the decayed factor from base size, factor=4 keeps target scale by default.
base_size: base size the build the bottom layer of pyramid
"""
if isinstance(factor, numbers.Number):
self.factor = round(sample_uniform(0, factor))
elif isinstance(factor, (tuple, list)) and len(factor) == 2:
self.factor = round(sample_uniform(factor[0], factor[1]))
else:
raise Exception('factor must be number or list with length 2')
# assert factor is valid
self.base_h, self.base_w = base_size[:2]
def __call__(self, img):
if self.factor == 0: return img
src_h, src_w = img.shape[:2]
cur_w, cur_h = self.base_w, self.base_h
scale_img = cv2.resize(img, (cur_w, cur_h), interpolation=get_interpolation())
for _ in range(self.factor):
scale_img = cv2.pyrDown(scale_img)
scale_img = cv2.resize(scale_img, (src_w, src_h), interpolation=get_interpolation())
return scale_img
class CVGaussianNoise(object):
def __init__(self, mean=0, var=20):
self.mean = mean
if isinstance(var, numbers.Number):
self.var = max(int(sample_asym(var)), 1)
elif isinstance(var, (tuple, list)) and len(var) == 2:
self.var = int(sample_uniform(var[0], var[1]))
else:
raise Exception('degree must be number or list with length 2')
def __call__(self, img):
noise = np.random.normal(self.mean, self.var**0.5, img.shape)
img = np.clip(img + noise, 0, 255).astype(np.uint8)
return img
class CVMotionBlur(object):
def __init__(self, degrees=12, angle=90):
if isinstance(degrees, numbers.Number):
self.degree = max(int(sample_asym(degrees)), 1)
elif isinstance(degrees, (tuple, list)) and len(degrees) == 2:
self.degree = int(sample_uniform(degrees[0], degrees[1]))
else:
raise Exception('degree must be number or list with length 2')
self.angle = sample_uniform(-angle, angle)
def __call__(self, img):
M = cv2.getRotationMatrix2D((self.degree // 2, self.degree // 2), self.angle, 1)
motion_blur_kernel = np.zeros((self.degree, self.degree))
motion_blur_kernel[self.degree // 2, :] = 1
motion_blur_kernel = cv2.warpAffine(motion_blur_kernel, M, (self.degree, self.degree))
motion_blur_kernel = motion_blur_kernel / self.degree
img = cv2.filter2D(img, -1, motion_blur_kernel)
img = np.clip(img, 0, 255).astype(np.uint8)
return img
class CVGeometry(object):
def __init__(self, degrees=15, translate=(0.3, 0.3), scale=(0.5, 2.),
shear=(45, 15), distortion=0.5, p=0.5):
self.p = p
type_p = random.random()
if type_p < 0.33:
self.transforms = CVRandomRotation(degrees=degrees)
elif type_p < 0.66:
self.transforms = CVRandomAffine(degrees=degrees, translate=translate, scale=scale, shear=shear)
else:
self.transforms = CVRandomPerspective(distortion=distortion)
def __call__(self, img):
if random.random() < self.p:
img = np.array(img)
return Image.fromarray(self.transforms(img))
else: return img
class CVDeterioration(object):
def __init__(self, var, degrees, factor, p=0.5):
self.p = p
transforms = []
if var is not None:
transforms.append(CVGaussianNoise(var=var))
if degrees is not None:
transforms.append(CVMotionBlur(degrees=degrees))
if factor is not None:
transforms.append(CVRescale(factor=factor))
random.shuffle(transforms)
transforms = Compose(transforms)
self.transforms = transforms
def __call__(self, img):
if random.random() < self.p:
img = np.array(img)
return Image.fromarray(self.transforms(img))
else: return img
class CVColorJitter(object):
def __init__(self, brightness=0.5, contrast=0.5, saturation=0.5, hue=0.1, p=0.5):
self.p = p
self.transforms = transforms.ColorJitter(brightness=brightness, contrast=contrast,
saturation=saturation, hue=hue)
def __call__(self, img):
if random.random() < self.p: return self.transforms(img)
else: return img