import cv2 import numpy as np from PIL import Image ## aug functions def identity_func(img): return img def autocontrast_func(img, cutoff=0): ''' same output as PIL.ImageOps.autocontrast ''' n_bins = 256 def tune_channel(ch): n = ch.size cut = cutoff * n // 100 if cut == 0: high, low = ch.max(), ch.min() else: hist = cv2.calcHist([ch], [0], None, [n_bins], [0, n_bins]) low = np.argwhere(np.cumsum(hist) > cut) low = 0 if low.shape[0] == 0 else low[0] high = np.argwhere(np.cumsum(hist[::-1]) > cut) high = n_bins - 1 if high.shape[0] == 0 else n_bins - 1 - high[0] if high <= low: table = np.arange(n_bins) else: scale = (n_bins - 1) / (high - low) offset = -low * scale table = np.arange(n_bins) * scale + offset table[table < 0] = 0 table[table > n_bins - 1] = n_bins - 1 table = table.clip(0, 255).astype(np.uint8) return table[ch] channels = [tune_channel(ch) for ch in cv2.split(img)] out = cv2.merge(channels) return out def equalize_func(img): ''' same output as PIL.ImageOps.equalize PIL's implementation is different from cv2.equalize ''' n_bins = 256 def tune_channel(ch): hist = cv2.calcHist([ch], [0], None, [n_bins], [0, n_bins]) non_zero_hist = hist[hist != 0].reshape(-1) step = np.sum(non_zero_hist[:-1]) // (n_bins - 1) if step == 0: return ch n = np.empty_like(hist) n[0] = step // 2 n[1:] = hist[:-1] table = (np.cumsum(n) // step).clip(0, 255).astype(np.uint8) return table[ch] channels = [tune_channel(ch) for ch in cv2.split(img)] out = cv2.merge(channels) return out def rotate_func(img, degree, fill=(0, 0, 0)): ''' like PIL, rotate by degree, not radians ''' H, W = img.shape[0], img.shape[1] center = W / 2, H / 2 M = cv2.getRotationMatrix2D(center, degree, 1) out = cv2.warpAffine(img, M, (W, H), borderValue=fill) return out def solarize_func(img, thresh=128): ''' same output as PIL.ImageOps.posterize ''' table = np.array([el if el < thresh else 255 - el for el in range(256)]) table = table.clip(0, 255).astype(np.uint8) out = table[img] return out def color_func(img, factor): ''' same output as PIL.ImageEnhance.Color ''' ## implementation according to PIL definition, quite slow # degenerate = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)[:, :, np.newaxis] # out = blend(degenerate, img, factor) # M = ( # np.eye(3) * factor # + np.float32([0.114, 0.587, 0.299]).reshape(3, 1) * (1. - factor) # )[np.newaxis, np.newaxis, :] M = ( np.float32([ [0.886, -0.114, -0.114], [-0.587, 0.413, -0.587], [-0.299, -0.299, 0.701]]) * factor + np.float32([[0.114], [0.587], [0.299]]) ) out = np.matmul(img, M).clip(0, 255).astype(np.uint8) return out def contrast_func(img, factor): """ same output as PIL.ImageEnhance.Contrast """ mean = np.sum(np.mean(img, axis=(0, 1)) * np.array([0.114, 0.587, 0.299])) table = np.array([( el - mean) * factor + mean for el in range(256) ]).clip(0, 255).astype(np.uint8) out = table[img] return out def brightness_func(img, factor): ''' same output as PIL.ImageEnhance.Contrast ''' table = (np.arange(256, dtype=np.float32) * factor).clip(0, 255).astype(np.uint8) out = table[img] return out def sharpness_func(img, factor): ''' The differences the this result and PIL are all on the 4 boundaries, the center areas are same ''' kernel = np.ones((3, 3), dtype=np.float32) kernel[1][1] = 5 kernel /= 13 degenerate = cv2.filter2D(img, -1, kernel) if factor == 0.0: out = degenerate elif factor == 1.0: out = img else: out = img.astype(np.float32) degenerate = degenerate.astype(np.float32)[1:-1, 1:-1, :] out[1:-1, 1:-1, :] = degenerate + factor * (out[1:-1, 1:-1, :] - degenerate) out = out.astype(np.uint8) return out def shear_x_func(img, factor, fill=(0, 0, 0)): H, W = img.shape[0], img.shape[1] M = np.float32([[1, factor, 0], [0, 1, 0]]) out = cv2.warpAffine(img, M, (W, H), borderValue=fill, flags=cv2.INTER_LINEAR).astype(np.uint8) return out def translate_x_func(img, offset, fill=(0, 0, 0)): ''' same output as PIL.Image.transform ''' H, W = img.shape[0], img.shape[1] M = np.float32([[1, 0, -offset], [0, 1, 0]]) out = cv2.warpAffine(img, M, (W, H), borderValue=fill, flags=cv2.INTER_LINEAR).astype(np.uint8) return out def translate_y_func(img, offset, fill=(0, 0, 0)): ''' same output as PIL.Image.transform ''' H, W = img.shape[0], img.shape[1] M = np.float32([[1, 0, 0], [0, 1, -offset]]) out = cv2.warpAffine(img, M, (W, H), borderValue=fill, flags=cv2.INTER_LINEAR).astype(np.uint8) return out def posterize_func(img, bits): ''' same output as PIL.ImageOps.posterize ''' out = np.bitwise_and(img, np.uint8(255 << (8 - bits))) return out def shear_y_func(img, factor, fill=(0, 0, 0)): H, W = img.shape[0], img.shape[1] M = np.float32([[1, 0, 0], [factor, 1, 0]]) out = cv2.warpAffine(img, M, (W, H), borderValue=fill, flags=cv2.INTER_LINEAR).astype(np.uint8) return out def cutout_func(img, pad_size, replace=(0, 0, 0)): replace = np.array(replace, dtype=np.uint8) H, W = img.shape[0], img.shape[1] rh, rw = np.random.random(2) pad_size = pad_size // 2 ch, cw = int(rh * H), int(rw * W) x1, x2 = max(ch - pad_size, 0), min(ch + pad_size, H) y1, y2 = max(cw - pad_size, 0), min(cw + pad_size, W) out = img.copy() out[x1:x2, y1:y2, :] = replace return out ### level to args def enhance_level_to_args(MAX_LEVEL): def level_to_args(level): return ((level / MAX_LEVEL) * 1.8 + 0.1,) return level_to_args def shear_level_to_args(MAX_LEVEL, replace_value): def level_to_args(level): level = (level / MAX_LEVEL) * 0.3 if np.random.random() > 0.5: level = -level return (level, replace_value) return level_to_args def translate_level_to_args(translate_const, MAX_LEVEL, replace_value): def level_to_args(level): level = (level / MAX_LEVEL) * float(translate_const) if np.random.random() > 0.5: level = -level return (level, replace_value) return level_to_args def cutout_level_to_args(cutout_const, MAX_LEVEL, replace_value): def level_to_args(level): level = int((level / MAX_LEVEL) * cutout_const) return (level, replace_value) return level_to_args def solarize_level_to_args(MAX_LEVEL): def level_to_args(level): level = int((level / MAX_LEVEL) * 256) return (level, ) return level_to_args def none_level_to_args(level): return () def posterize_level_to_args(MAX_LEVEL): def level_to_args(level): level = int((level / MAX_LEVEL) * 4) return (level, ) return level_to_args def rotate_level_to_args(MAX_LEVEL, replace_value): def level_to_args(level): level = (level / MAX_LEVEL) * 30 if np.random.random() < 0.5: level = -level return (level, replace_value) return level_to_args func_dict = { 'Identity': identity_func, 'AutoContrast': autocontrast_func, 'Equalize': equalize_func, 'Rotate': rotate_func, 'Solarize': solarize_func, 'Color': color_func, 'Contrast': contrast_func, 'Brightness': brightness_func, 'Sharpness': sharpness_func, 'ShearX': shear_x_func, 'TranslateX': translate_x_func, 'TranslateY': translate_y_func, 'Posterize': posterize_func, 'ShearY': shear_y_func, } translate_const = 10 MAX_LEVEL = 10 replace_value = (128, 128, 128) arg_dict = { 'Identity': none_level_to_args, 'AutoContrast': none_level_to_args, 'Equalize': none_level_to_args, 'Rotate': rotate_level_to_args(MAX_LEVEL, replace_value), 'Solarize': solarize_level_to_args(MAX_LEVEL), 'Color': enhance_level_to_args(MAX_LEVEL), 'Contrast': enhance_level_to_args(MAX_LEVEL), 'Brightness': enhance_level_to_args(MAX_LEVEL), 'Sharpness': enhance_level_to_args(MAX_LEVEL), 'ShearX': shear_level_to_args(MAX_LEVEL, replace_value), 'TranslateX': translate_level_to_args( translate_const, MAX_LEVEL, replace_value ), 'TranslateY': translate_level_to_args( translate_const, MAX_LEVEL, replace_value ), 'Posterize': posterize_level_to_args(MAX_LEVEL), 'ShearY': shear_level_to_args(MAX_LEVEL, replace_value), } class RandomAugment(object): def __init__(self, N=2, M=10, isPIL=False, returnPIL=False, augs=[]): self.N = N self.M = M self.isPIL = isPIL self.returnPIL = returnPIL if augs: self.augs = augs else: self.augs = list(arg_dict.keys()) def get_random_ops(self): sampled_ops = np.random.choice(self.augs, self.N) return [(op, 0.5, self.M) for op in sampled_ops] def __call__(self, img): if self.isPIL: img = np.array(img) ops = self.get_random_ops() for name, prob, level in ops: if np.random.random() > prob: continue args = arg_dict[name](level) img = func_dict[name](img, *args) if self.returnPIL: img = img.astype('uint8') img = Image.fromarray(img) return img if __name__ == '__main__': a = RandomAugment() img = np.random.randn(32, 32, 3) a(img)