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# YOLOv5 π by Ultralytics, AGPL-3.0 license | |
""" | |
Image augmentation functions | |
""" | |
import math | |
import random | |
import cv2 | |
import numpy as np | |
from ..augmentations import box_candidates | |
from ..general import resample_segments, segment2box | |
def mixup(im, labels, segments, im2, labels2, segments2): | |
# Applies MixUp augmentation https://arxiv.org/pdf/1710.09412.pdf | |
r = np.random.beta(32.0, 32.0) # mixup ratio, alpha=beta=32.0 | |
im = (im * r + im2 * (1 - r)).astype(np.uint8) | |
labels = np.concatenate((labels, labels2), 0) | |
segments = np.concatenate((segments, segments2), 0) | |
return im, labels, segments | |
def random_perspective(im, | |
targets=(), | |
segments=(), | |
degrees=10, | |
translate=.1, | |
scale=.1, | |
shear=10, | |
perspective=0.0, | |
border=(0, 0)): | |
# torchvision.transforms.RandomAffine(degrees=(-10, 10), translate=(.1, .1), scale=(.9, 1.1), shear=(-10, 10)) | |
# targets = [cls, xyxy] | |
height = im.shape[0] + border[0] * 2 # shape(h,w,c) | |
width = im.shape[1] + border[1] * 2 | |
# Center | |
C = np.eye(3) | |
C[0, 2] = -im.shape[1] / 2 # x translation (pixels) | |
C[1, 2] = -im.shape[0] / 2 # y translation (pixels) | |
# Perspective | |
P = np.eye(3) | |
P[2, 0] = random.uniform(-perspective, perspective) # x perspective (about y) | |
P[2, 1] = random.uniform(-perspective, perspective) # y perspective (about x) | |
# Rotation and Scale | |
R = np.eye(3) | |
a = random.uniform(-degrees, degrees) | |
# a += random.choice([-180, -90, 0, 90]) # add 90deg rotations to small rotations | |
s = random.uniform(1 - scale, 1 + scale) | |
# s = 2 ** random.uniform(-scale, scale) | |
R[:2] = cv2.getRotationMatrix2D(angle=a, center=(0, 0), scale=s) | |
# Shear | |
S = np.eye(3) | |
S[0, 1] = math.tan(random.uniform(-shear, shear) * math.pi / 180) # x shear (deg) | |
S[1, 0] = math.tan(random.uniform(-shear, shear) * math.pi / 180) # y shear (deg) | |
# Translation | |
T = np.eye(3) | |
T[0, 2] = (random.uniform(0.5 - translate, 0.5 + translate) * width) # x translation (pixels) | |
T[1, 2] = (random.uniform(0.5 - translate, 0.5 + translate) * height) # y translation (pixels) | |
# Combined rotation matrix | |
M = T @ S @ R @ P @ C # order of operations (right to left) is IMPORTANT | |
if (border[0] != 0) or (border[1] != 0) or (M != np.eye(3)).any(): # image changed | |
if perspective: | |
im = cv2.warpPerspective(im, M, dsize=(width, height), borderValue=(114, 114, 114)) | |
else: # affine | |
im = cv2.warpAffine(im, M[:2], dsize=(width, height), borderValue=(114, 114, 114)) | |
# Visualize | |
# import matplotlib.pyplot as plt | |
# ax = plt.subplots(1, 2, figsize=(12, 6))[1].ravel() | |
# ax[0].imshow(im[:, :, ::-1]) # base | |
# ax[1].imshow(im2[:, :, ::-1]) # warped | |
# Transform label coordinates | |
n = len(targets) | |
new_segments = [] | |
if n: | |
new = np.zeros((n, 4)) | |
segments = resample_segments(segments) # upsample | |
for i, segment in enumerate(segments): | |
xy = np.ones((len(segment), 3)) | |
xy[:, :2] = segment | |
xy = xy @ M.T # transform | |
xy = (xy[:, :2] / xy[:, 2:3] if perspective else xy[:, :2]) # perspective rescale or affine | |
# clip | |
new[i] = segment2box(xy, width, height) | |
new_segments.append(xy) | |
# filter candidates | |
i = box_candidates(box1=targets[:, 1:5].T * s, box2=new.T, area_thr=0.01) | |
targets = targets[i] | |
targets[:, 1:5] = new[i] | |
new_segments = np.array(new_segments)[i] | |
return im, targets, new_segments | |