Table Of Contents
Table Of Contents

Source code for gluoncv.data.transforms.block

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# coding: utf-8
# pylint: disable= arguments-differ
# pylint: disable= missing-docstring
"Addtional image transforms."

import random
import math
import numpy as np
from mxnet import image, nd
from mxnet.gluon import Block


__all__ = ['RandomCrop', 'RandomErasing']


[docs]class RandomCrop(Block): """Randomly crop `src` with `size` (width, height). Padding is optional. Upsample result if `src` is smaller than `size`. Parameters ---------- size : int or tuple of (W, H) Size of the final output. pad: int or tuple if int, size of the zero-padding if tuple, number of values padded to the edges of each axis. ((before_1, after_1), ... (before_N, after_N)) unique pad widths for each axis. ((before, after),) yields same before and after pad for each axis. (pad,) or int is a shortcut for before = after = pad width for all axes. interpolation : int Interpolation method for resizing. By default uses bilinear interpolation. See OpenCV's resize function for available choices. Inputs: - **data**: input tensor with (Hi x Wi x C) shape. Outputs: - **out**: output tensor with ((H+2*pad) x (W+2*pad) x C) shape. """ def __init__(self, size, pad=None, interpolation=2): super(RandomCrop, self).__init__() numeric_types = (float, int, np.generic) if isinstance(size, numeric_types): size = (size, size) self._args = (size, interpolation) if isinstance(pad, int): self.pad = ((pad, pad), (pad, pad), (0, 0)) else: self.pad = pad
[docs] def forward(self, x): if self.pad: x_pad = np.pad(x.asnumpy(), self.pad, mode='constant', constant_values=0) return image.random_crop(nd.array(x_pad), *self._args)[0]
[docs]class RandomErasing(Block): """Randomly erasing the area in `src` between `s_min` and `s_max` with `probability`. `ratio` controls the ratio between width and height. `mean` means the value in erasing area. Parameters ---------- probability : float Probability of erasing. s_min : float Min area to all area. s_max : float Max area to all area. ratio : float The ratio between width and height. mean : int or tuple of (R, G, B) The value in erasing area. Inputs: - **data**: input tensor with (Hi x Wi x C) shape. Outputs: - **out**: output tensor with (Hi x Wi x C) shape. """ def __init__(self, probability=0.5, s_min=0.02, s_max=0.4, ratio=0.3, mean=(125.31, 122.96, 113.86)): super(RandomErasing, self).__init__() self.probability = probability self.mean = mean self.s_min = s_min self.s_max = s_max self.ratio = ratio
[docs] def forward(self, x): if not isinstance(self.probability, int): raise TypeError('Got inappropriate size arg') if not isinstance(self.s_min, int): raise TypeError('Got inappropriate size arg') if not isinstance(self.s_max, int): raise TypeError('Got inappropriate size arg') if not isinstance(self.ratio, int): raise TypeError('Got inappropriate size arg') if not isinstance(self.mean, (int, tuple)): raise TypeError('Got inappropriate size arg') if random.uniform(0, 1) > self.probability: return x width, height, _ = x.shape area = width * height target_area = random.uniform(self.s_min, self.s_max) * area aspect_ratio = random.uniform(self.ratio, 1/self.ratio) w = int(round(math.sqrt(target_area * aspect_ratio))) h = int(round(math.sqrt(target_area / aspect_ratio))) if w < width and h < height: x1 = random.randint(0, width - w) y1 = random.randint(0, height - h) x[x1:x1+w, y1:y1+h, 0] = self.mean[0] x[x1:x1+w, y1:y1+h, 1] = self.mean[1] x[x1:x1+w, y1:y1+h, 2] = self.mean[2] return x