aug_lib.py

import numpy as np
import re
from PIL import ImageOps, ImageEnhance, ImageFilter, Image, ImageDraw
import random
from dataclasses import dataclass
from typing import Union


@dataclass
class MinMax:
    min: Union[float, int]
    max: Union[float, int]


@dataclass
class MinMaxVals:
    shear: MinMax = MinMax(.0, .3)
    translate: MinMax = MinMax(0, 10)  # different from uniaug: MinMax(0,14.4)
    rotate: MinMax = MinMax(0, 30)
    solarize: MinMax = MinMax(0, 256)
    posterize: MinMax = MinMax(0, 4)  # different from uniaug: MinMax(4,8)
    enhancer: MinMax = MinMax(.1, 1.9)
    cutout: MinMax = MinMax(.0, .2)




def float_parameter(level, maxval):
    """Helper function to scale `val` between 0 and maxval .

  Args:
    level: Level of the operation that will be between [0, `PARAMETER_MAX`].
    maxval: Maximum value that the operation can have. This will be scaled
      to level/PARAMETER_MAX.

  Returns:
    A float that results from scaling `maxval` according to `level`.
  """
    return float(level) * maxval / PARAMETER_MAX


def int_parameter(level, maxval):
    """Helper function to scale `val` between 0 and maxval .

  Args:
    level: Level of the operation that will be between [0, `PARAMETER_MAX`].
    maxval: Maximum value that the operation can have. This will be scaled
      to level/PARAMETER_MAX.

  Returns:
    An int that results from scaling `maxval` according to `level`.
  """
    return int(level * maxval / PARAMETER_MAX)


class TransformFunction(object):
    """Wraps the Transform function for pretty printing options."""

    def __init__(self, func, name):
        self.f = func
        self.name = name

    def __repr__(self):
        return '<' + self.name + '>'

    def __call__(self, pil_img):
        return self.f(pil_img)


class TransformT(object):
    """Each instance of this class represents a specific transform."""

    def __init__(self, name, xform_fn):
        self.name = name
        self.xform = xform_fn

    def __repr__(self):
        return '<' + self.name + '>'

    def pil_transformer(self, probability, level):
        def return_function(im):
            if random.random() < probability:
                im = self.xform(im, level)
            return im

        name = self.name + '({:.1f},{})'.format(probability, level)
        return TransformFunction(return_function, name)


################## Transform Functions ##################
identity = TransformT('identity', lambda pil_img, level: pil_img)
flip_lr = TransformT(
    'FlipLR',
    lambda pil_img, level: pil_img.transpose(Image.FLIP_LEFT_RIGHT))
flip_ud = TransformT(
    'FlipUD',
    lambda pil_img, level: pil_img.transpose(Image.FLIP_TOP_BOTTOM))
# pylint:disable=g-long-lambda
auto_contrast = TransformT(
    'AutoContrast',
    lambda pil_img, level: ImageOps.autocontrast(
        pil_img))
equalize = TransformT(
    'Equalize',
    lambda pil_img, level: ImageOps.equalize(
        pil_img))
invert = TransformT(
    'Invert',
    lambda pil_img, level: ImageOps.invert(
        pil_img))
# pylint:enable=g-long-lambda
blur = TransformT(
    'Blur', lambda pil_img, level: pil_img.filter(ImageFilter.BLUR))
smooth = TransformT(
    'Smooth',
    lambda pil_img, level: pil_img.filter(ImageFilter.SMOOTH))


def _rotate_impl(pil_img, level):
    """Rotates `pil_img` from -30 to 30 degrees depending on `level`."""
    degrees = int_parameter(level, min_max_vals.rotate.max)
    if random.random() > 0.5:
        degrees = -degrees
    return pil_img.rotate(degrees)


rotate = TransformT('Rotate', _rotate_impl)


def _posterize_impl(pil_img, level):
    """Applies PIL Posterize to `pil_img`."""
    level = int_parameter(level, min_max_vals.posterize.max - min_max_vals.posterize.min)
    return ImageOps.posterize(pil_img, min_max_vals.posterize.max - level)


posterize = TransformT('Posterize', _posterize_impl)


def _shear_x_impl(pil_img, level):
    """Applies PIL ShearX to `pil_img`.

  The ShearX operation shears the image along the horizontal axis with `level`
  magnitude.

  Args:
    pil_img: Image in PIL object.
    level: Strength of the operation specified as an Integer from
      [0, `PARAMETER_MAX`].

  Returns:
    A PIL Image that has had ShearX applied to it.
  """
    level = float_parameter(level, min_max_vals.shear.max)
    if random.random() > 0.5:
        level = -level
    return pil_img.transform(pil_img.size, Image.AFFINE, (1, level, 0, 0, 1, 0))


shear_x = TransformT('ShearX', _shear_x_impl)


def _shear_y_impl(pil_img, level):
    """Applies PIL ShearY to `pil_img`.

  The ShearY operation shears the image along the vertical axis with `level`
  magnitude.

  Args:
    pil_img: Image in PIL object.
    level: Strength of the operation specified as an Integer from
      [0, `PARAMETER_MAX`].

  Returns:
    A PIL Image that has had ShearX applied to it.
  """
    level = float_parameter(level, min_max_vals.shear.max)
    if random.random() > 0.5:
        level = -level
    return pil_img.transform(pil_img.size, Image.AFFINE, (1, 0, 0, level, 1, 0))


shear_y = TransformT('ShearY', _shear_y_impl)


def _translate_x_impl(pil_img, level):
    """Applies PIL TranslateX to `pil_img`.

  Translate the image in the horizontal direction by `level`
  number of pixels.

  Args:
    pil_img: Image in PIL object.
    level: Strength of the operation specified as an Integer from
      [0, `PARAMETER_MAX`].

  Returns:
    A PIL Image that has had TranslateX applied to it.
  """
    level = int_parameter(level, min_max_vals.translate.max)
    if random.random() > 0.5:
        level = -level
    return pil_img.transform(pil_img.size, Image.AFFINE, (1, 0, level, 0, 1, 0))


translate_x = TransformT('TranslateX', _translate_x_impl)


def _translate_y_impl(pil_img, level):
    """Applies PIL TranslateY to `pil_img`.

  Translate the image in the vertical direction by `level`
  number of pixels.

  Args:
    pil_img: Image in PIL object.
    level: Strength of the operation specified as an Integer from
      [0, `PARAMETER_MAX`].

  Returns:
    A PIL Image that has had TranslateY applied to it.
  """
    level = int_parameter(level, min_max_vals.translate.max)
    if random.random() > 0.5:
        level = -level
    return pil_img.transform(pil_img.size, Image.AFFINE, (1, 0, 0, 0, 1, level))


translate_y = TransformT('TranslateY', _translate_y_impl)


def _crop_impl(pil_img, level, interpolation=Image.BILINEAR):
    """Applies a crop to `pil_img` with the size depending on the `level`."""
    level = int_parameter(level, 10)
    w = pil_img.width
    h = pil_img.height
    cropped = pil_img.crop((level, level, w - level, h - level))
    resized = cropped.resize((w, h), interpolation)
    return resized


crop_bilinear = TransformT('CropBilinear', _crop_impl)


def _solarize_impl(pil_img, level):
    """Applies PIL Solarize to `pil_img`.

  Translate the image in the vertical direction by `level`
  number of pixels.

  Args:
    pil_img: Image in PIL object.
    level: Strength of the operation specified as an Integer from
      [0, `PARAMETER_MAX`].

  Returns:
    A PIL Image that has had Solarize applied to it.
  """
    level = int_parameter(level, min_max_vals.solarize.max)
    return ImageOps.solarize(pil_img, 256 - level)


solarize = TransformT('Solarize', _solarize_impl)


def _enhancer_impl(enhancer, minimum=None, maximum=None):
    """Sets level to be between 0.1 and 1.8 for ImageEnhance transforms of PIL."""

    def impl(pil_img, level):
        mini = min_max_vals.enhancer.min if minimum is None else minimum
        maxi = min_max_vals.enhancer.max if maximum is None else maximum
        v = float_parameter(level, maxi - mini) + mini  # going to 0 just destroys it
        return enhancer(pil_img).enhance(v)

    return impl


color = TransformT('Color', _enhancer_impl(ImageEnhance.Color))
ohl_color = TransformT('Color', _enhancer_impl(ImageEnhance.Color, .3, .9))
contrast = TransformT('Contrast', _enhancer_impl(ImageEnhance.Contrast))
brightness = TransformT('Brightness', _enhancer_impl(
    ImageEnhance.Brightness))
sharpness = TransformT('Sharpness', _enhancer_impl(ImageEnhance.Sharpness))
contour = TransformT(
    'Contour', lambda pil_img, level: pil_img.filter(ImageFilter.CONTOUR))
detail = TransformT(
    'Detail', lambda pil_img, level: pil_img.filter(ImageFilter.DETAIL))
edge_enhance = TransformT(
    'EdgeEnhance', lambda pil_img, level: pil_img.filter(ImageFilter.EDGE_ENHANCE))
sharpen = TransformT(
    'Sharpen', (lambda pil_img, level: pil_img.filter(ImageFilter.SHARPEN)))
max_ = TransformT(
    'Max', lambda pil_img, level: pil_img.filter(ImageFilter.MaxFilter))
min_ = TransformT(
    'Min', lambda pil_img, level: pil_img.filter(ImageFilter.MinFilter))
median = TransformT(
    'Median', lambda pil_img, level: pil_img.filter(ImageFilter.MedianFilter))
gaussian = TransformT(
    'Gaussian', lambda pil_img, level: pil_img.filter(ImageFilter.GaussianBlur))



def _mirrored_enhancer_impl(enhancer, minimum=None, maximum=None):
    """Sets level to be between 0.1 and 1.8 for ImageEnhance transforms of PIL."""

    def impl(pil_img, level):
        mini = min_max_vals.enhancer.min if minimum is None else minimum
        maxi = min_max_vals.enhancer.max if maximum is None else maximum
        assert mini == 0., "This enhancer is used with a strength space that is mirrored around one."
        v = float_parameter(level, maxi - mini) + mini  # going to 0 just destroys it
        if random.random() < .5:
            v = -v
        return enhancer(pil_img).enhance(1. + v)

    return impl


mirrored_color = TransformT('Color', _mirrored_enhancer_impl(ImageEnhance.Color))
mirrored_contrast = TransformT('Contrast', _mirrored_enhancer_impl(ImageEnhance.Contrast))
mirrored_brightness = TransformT('Brightness', _mirrored_enhancer_impl(
    ImageEnhance.Brightness))
mirrored_sharpness = TransformT('Sharpness', _mirrored_enhancer_impl(ImageEnhance.Sharpness))


def CutoutDefault(img, v):  # [0, 60] => percentage: [0, 0.2]
    # assert 0 <= v <= 20
    if v <= 0:
        return img
    w, h = img.size
    x0 = np.random.uniform(w)
    y0 = np.random.uniform(h)

    x0 = int(max(0, x0 - v / 2.))
    y0 = int(max(0, y0 - v / 2.))
    x1 = min(w, x0 + v)
    y1 = min(h, y0 + v)

    xy = (x0, y0, x1, y1)
    color = (0, 0, 0)
    img = img.copy()
    ImageDraw.Draw(img).rectangle(xy, color)
    return img


cutout = TransformT('Cutout',
                    lambda img, l: CutoutDefault(img, int_parameter(l, img.size[0] * min_max_vals.cutout.max)))




blend_images = None


def blend(img1, v):
    if blend_images is None:
        print("please set google_transformations.blend_images before using the enlarged_randaug search space.")
    i = np.random.choice(len(blend_images))
    img2 = blend_images[i]
    m = float_parameter(v, .4)
    return Image.blend(img1, img2, m)


sample_pairing = TransformT('SamplePairing', blend)


def set_augmentation_space(augmentation_space, num_strengths, custom_augmentation_space_augs=None):
    global ALL_TRANSFORMS, min_max_vals, PARAMETER_MAX
    assert num_strengths > 0
    PARAMETER_MAX = num_strengths - 1
    if 'wide' in augmentation_space:
        min_max_vals = MinMaxVals(
            shear=MinMax(.0, .99),
            translate=MinMax(0, 32),
            rotate=MinMax(0, 135),
            solarize=MinMax(0, 256),
            posterize=MinMax(2, 8),
            enhancer=MinMax(.01, 2.),
            cutout=MinMax(.0, .6),
        )
    elif ('uniaug' in augmentation_space) or ('randaug' in augmentation_space):
        min_max_vals = MinMaxVals(
            posterize=MinMax(4, 8),
            translate=MinMax(0, 14.4)
        )
    elif 'fixmirror' in augmentation_space:
        min_max_vals = MinMaxVals(
            posterize=MinMax(4, 8),
            enhancer=MinMax(0., .9)
        )
    elif 'fiximagenet' in augmentation_space:
        min_max_vals = MinMaxVals(
            posterize=MinMax(4, 8),
            translate=MinMax(0, 70)
        )
    elif 'fix' in augmentation_space:
        min_max_vals = MinMaxVals(
            posterize=MinMax(4, 8)
        )
    elif 'ohl' in augmentation_space:
        assert PARAMETER_MAX == 2
        min_max_vals = MinMaxVals(
            shear=MinMax(.1, .3),
            translate=MinMax(5, 14),
            rotate=MinMax(10, 30),
            solarize=MinMax(26, 179),
            posterize=MinMax(4, 7),
            enhancer=MinMax(1.3, 1.9),
            cutout=MinMax(.0, .6),
        )
    else:
        min_max_vals = MinMaxVals()

    if 'xlong' in augmentation_space:
        ALL_TRANSFORMS = [
            identity,
            auto_contrast,
            equalize,
            rotate,
            solarize,
            color,
            posterize,
            contrast,
            brightness,
            sharpness,
            shear_x,
            shear_y,
            translate_x,
            translate_y,
            blur,
            invert,
            flip_lr,
            flip_ud,
            cutout,
            crop_bilinear,
            contour,
            detail,
            edge_enhance,
            sharpen,
            max_,
            min_,
            median,
            gaussian
        ]
    elif 'rasubsetof' in augmentation_space:
        r = re.findall(r'rasubsetof(\d+)', augmentation_space)
        assert len(r) == 1
        ALL_TRANSFORMS = random.sample(ALL_TRANSFORMS, int(r[0]))
        print(f"Subsampled {len(ALL_TRANSFORMS)} augs: {ALL_TRANSFORMS}")
    elif 'fixmirror' in augmentation_space:
        ALL_TRANSFORMS = [
            identity,
            auto_contrast,
            equalize,
            rotate,
            solarize,
            mirrored_color,  # enhancer
            posterize,
            mirrored_contrast,  # enhancer
            mirrored_brightness,  # enhancer
            mirrored_sharpness,  # enhancer
            shear_x,
            shear_y,
            translate_x,
            translate_y
        ]
    elif 'long' in augmentation_space:
        ALL_TRANSFORMS = [
            identity,
            auto_contrast,
            equalize,
            rotate,
            solarize,
            color,
            posterize,
            contrast,
            brightness,
            sharpness,
            shear_x,
            shear_y,
            translate_x,
            translate_y,
            # sample_pairing,
            blur,
            invert,
            flip_lr,
            flip_ud,
            cutout
        ]
    elif 'uniaug' in augmentation_space:
        ALL_TRANSFORMS = [
            identity,
            shear_x,
            shear_y,
            translate_x,
            translate_y,
            rotate,
            auto_contrast,
            invert,  # only uniaug
            equalize,
            solarize,
            posterize,
            contrast,
            color,
            brightness,
            sharpness,
            cutout  # only uniaug
        ]
    elif 'autoaug_paper' in augmentation_space:
        ALL_TRANSFORMS = [
            shear_x,
            shear_y,
            translate_x,
            translate_y,
            rotate,
            auto_contrast,
            invert,
            equalize,
            solarize,
            posterize,
            contrast,
            color,
            brightness,
            sharpness,
            cutout,
            sample_pairing
        ]
    elif 'full' in augmentation_space:
        ALL_TRANSFORMS = [
            flip_lr,
            flip_ud,
            auto_contrast,
            equalize,
            invert,
            rotate,
            posterize,
            crop_bilinear,
            solarize,
            color,
            contrast,
            brightness,
            sharpness,
            shear_x,
            shear_y,
            translate_x,
            translate_y,
            cutout,
            blur,
            smooth
        ]
    elif 'ohl' in augmentation_space:
        ALL_TRANSFORMS = [
            shear_x,  # ok
            shear_y,  # ok
            translate_x,  # ok
            translate_y,  # ok
            rotate,  # ok
            ohl_color,  # nok
            posterize,  # ok
            solarize,  # ok
            contrast,  # ok
            sharpness,  # ok
            brightness,  # ok
            auto_contrast,
            equalize,
            invert
        ]
    elif 'custom' in augmentation_space:
        assert custom_augmentation_space_augs is not None

        custom_augmentation_space_augs_mapping = {
            'identity': identity,
            'auto_contrast': auto_contrast,
            'equalize': equalize,
            'rotate': rotate,
            'solarize': solarize,
            'color': color,
            'posterize': posterize,
            'contrast': contrast,
            'brightness': brightness,
            'sharpness': sharpness,
            'shear_x': shear_x,
            'shear_y': shear_y,
            'translate_x': translate_x,
            'translate_y': translate_y,
            # sample_pairing,
            'blur': blur,
            'invert': invert,
            'flip_lr': flip_lr,
            'flip_ud': flip_ud,
            'cutout': cutout,
            'crop_bilinear': crop_bilinear,
            'contour': contour,
            'detail': detail,
            'edge_enhance': edge_enhance,
            'sharpen': sharpen,
            'max_': max_,
            'min_': min_,
            'median': median,
            'gaussian': gaussian
        }
        ALL_TRANSFORMS = []
        ALL_TRANSFORMS += [
            custom_augmentation_space_augs_mapping[aug] for aug in custom_augmentation_space_augs
        ]
        print("CUSTOM Augs set to:", ALL_TRANSFORMS)
    else:
        if 'standard' not in augmentation_space:
            raise ValueError(f"Unknown search space {augmentation_space}")
        ALL_TRANSFORMS = [
            identity,
            auto_contrast,
            equalize,
            rotate,  # extra coin-flip
            solarize,
            color,  # enhancer
            posterize,
            contrast,  # enhancer
            brightness,  # enhancer
            sharpness,  # enhancer
            shear_x,  # extra coin-flip
            shear_y,  # extra coin-flip
            translate_x,  # extra coin-flip
            translate_y  # extra coin-flip
        ]

set_augmentation_space('fixed_standard', 31)


def apply_augmentation(aug_idx, m, img):
    return ALL_TRANSFORMS[aug_idx].pil_transformer(1., m)(img)


def num_augmentations():
    return len(ALL_TRANSFORMS)


class TrivialAugment:
    def __call__(self, img):
        op = random.choices(ALL_TRANSFORMS, k=1)[0]
        level = random.randint(0, PARAMETER_MAX)
        img = op.pil_transformer(1., level)(img)
        return img


class RandAugment:
    def __init__(self, n, m):
        self.n = n
        self.m = m  # [0, 30]

    def __call__(self, img):
        ops = random.choices(ALL_TRANSFORMS, k=self.n)
        for op in ops:
            img = op.pil_transformer(1., self.m)(img)

        return img


class UniAugment:
    def __call__(self, img):
        ops = random.choices(ALL_TRANSFORMS, k=2)
        for op in ops:
            level = random.randint(0, PARAMETER_MAX)
            img = op.pil_transformer(0.5, level)(img)
        return img


class UniAugmentWeighted:
    def __init__(self, n, probs):
        self.n = n
        self.probs = probs  # [prob of zero augs, prob of one aug, ..]

    def __call__(self, img):
        k = random.choices(range(len(self.probs)), self.probs)[0]
        ops = random.choices(ALL_TRANSFORMS, k=k)
        for op in ops:
            level = random.randint(0, PARAMETER_MAX)
            img = op.pil_transformer(1., level)(img)
        return img