Source code for yolort.v5.utils.augmentations

# YOLOv5 by Ultralytics, GPL-3.0 license
"""
Image augmentation functions
"""

import logging
import math
import random
from typing import Tuple

import numpy as np

try:
    import cv2
except ImportError:
    cv2 = None

from .general import colorstr, segment2box, resample_segments, check_version
from .metrics import bbox_ioa


class Albumentations:
    # YOLOv5 Albumentations class (optional, only used if package is installed)
    def __init__(self):
        self.transform = None
        try:
            import albumentations as A

            check_version(A.__version__, "1.0.3")  # version requirement

            self.transform = A.Compose(
                [A.Blur(p=0.1), A.MedianBlur(p=0.1), A.ToGray(p=0.01)],
                bbox_params=A.BboxParams(format="yolo", label_fields=["class_labels"]),
            )

            logging.info(
                colorstr("albumentations: ") + ", ".join(f"{x}" for x in self.transform.transforms if x.p)
            )
        except ImportError:  # package not installed, skip
            pass
        except Exception as e:
            logging.info(colorstr("albumentations: ") + f"{e}")

    def __call__(self, im, labels, p=1.0):
        if self.transform and random.random() < p:
            # transformed
            new = self.transform(image=im, bboxes=labels[:, 1:], class_labels=labels[:, 0])
            im = new["image"]
            labels = np.array([[c, *b] for c, b in zip(new["class_labels"], new["bboxes"])])
        return im, labels


def augment_hsv(im, hgain=0.5, sgain=0.5, vgain=0.5):
    # HSV color-space augmentation
    if hgain or sgain or vgain:
        r = np.random.uniform(-1, 1, 3) * [hgain, sgain, vgain] + 1  # random gains
        hue, sat, val = cv2.split(cv2.cvtColor(im, cv2.COLOR_BGR2HSV))
        dtype = im.dtype  # uint8

        x = np.arange(0, 256, dtype=r.dtype)
        lut_hue = ((x * r[0]) % 180).astype(dtype)
        lut_sat = np.clip(x * r[1], 0, 255).astype(dtype)
        lut_val = np.clip(x * r[2], 0, 255).astype(dtype)

        im_hsv = cv2.merge((cv2.LUT(hue, lut_hue), cv2.LUT(sat, lut_sat), cv2.LUT(val, lut_val)))
        cv2.cvtColor(im_hsv, cv2.COLOR_HSV2BGR, dst=im)  # no return needed


def hist_equalize(im, clahe=True, bgr=False):
    # Equalize histogram on BGR image 'im' with im.shape(n,m,3) and range 0-255
    yuv = cv2.cvtColor(im, cv2.COLOR_BGR2YUV if bgr else cv2.COLOR_RGB2YUV)
    if clahe:
        c = cv2.createCLAHE(clipLimit=2.0, tileGridSize=(8, 8))
        yuv[:, :, 0] = c.apply(yuv[:, :, 0])
    else:
        yuv[:, :, 0] = cv2.equalizeHist(yuv[:, :, 0])  # equalize Y channel histogram
    return cv2.cvtColor(yuv, cv2.COLOR_YUV2BGR if bgr else cv2.COLOR_YUV2RGB)  # convert YUV image to RGB


def replicate(im, labels):
    # Replicate labels
    h, w = im.shape[:2]
    boxes = labels[:, 1:].astype(int)
    x1, y1, x2, y2 = boxes.T
    s = ((x2 - x1) + (y2 - y1)) / 2  # side length (pixels)
    for i in s.argsort()[: round(s.size * 0.5)]:  # smallest indices
        x1b, y1b, x2b, y2b = boxes[i]
        bh, bw = y2b - y1b, x2b - x1b
        yc, xc = int(random.uniform(0, h - bh)), int(random.uniform(0, w - bw))  # offset x, y
        x1a, y1a, x2a, y2a = [xc, yc, xc + bw, yc + bh]
        im[y1a:y2a, x1a:x2a] = im[y1b:y2b, x1b:x2b]  # im4[ymin:ymax, xmin:xmax]
        labels = np.append(labels, [[labels[i, 0], x1a, y1a, x2a, y2a]], axis=0)

    return im, labels


[docs]def letterbox( im: np.ndarray, new_shape: Tuple[int, int] = (640, 640), color: Tuple[int, int, int] = (114, 114, 114), auto: bool = True, scale_fill: bool = False, scaleup: bool = True, stride: int = 32, ): # Resize and pad image while meeting stride-multiple constraints shape = im.shape[:2] # current shape [height, width] if isinstance(new_shape, int): new_shape = (new_shape, new_shape) # Scale ratio (new / old) r = min(new_shape[0] / shape[0], new_shape[1] / shape[1]) if not scaleup: # only scale down, do not scale up (for better val mAP) r = min(r, 1.0) # Compute padding ratio = r, r # width, height ratios new_unpad = int(round(shape[1] * r)), int(round(shape[0] * r)) dw, dh = new_shape[1] - new_unpad[0], new_shape[0] - new_unpad[1] # wh padding if auto: # minimum rectangle dw, dh = np.mod(dw, stride), np.mod(dh, stride) # wh padding elif scale_fill: # stretch dw, dh = 0.0, 0.0 new_unpad = (new_shape[1], new_shape[0]) ratio = new_shape[1] / shape[1], new_shape[0] / shape[0] # width, height ratios dw /= 2 # divide padding into 2 sides dh /= 2 if shape[::-1] != new_unpad: # resize im = cv2.resize(im, new_unpad, interpolation=cv2.INTER_LINEAR) top, bottom = int(round(dh - 0.1)), int(round(dh + 0.1)) left, right = int(round(dw - 0.1)), int(round(dw + 0.1)) im = cv2.copyMakeBorder(im, top, bottom, left, right, cv2.BORDER_CONSTANT, value=color) # add border return im, ratio, (dw, dh)
def random_perspective( im, targets=(), segments=(), degrees=10, translate=0.1, scale=0.1, 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) if n: use_segments = any(x.any() for x in segments) new = np.zeros((n, 4)) if use_segments: # warp segments 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 # perspective rescale or affine xy = xy[:, :2] / xy[:, 2:3] if perspective else xy[:, :2] # clip new[i] = segment2box(xy, width, height) else: # warp boxes xy = np.ones((n * 4, 3)) # x1y1, x2y2, x1y2, x2y1 xy[:, :2] = targets[:, [1, 2, 3, 4, 1, 4, 3, 2]].reshape(n * 4, 2) xy = xy @ M.T # transform # perspective rescale or affine xy = (xy[:, :2] / xy[:, 2:3] if perspective else xy[:, :2]).reshape(n, 8) # create new boxes x = xy[:, [0, 2, 4, 6]] y = xy[:, [1, 3, 5, 7]] new = np.concatenate((x.min(1), y.min(1), x.max(1), y.max(1))).reshape(4, n).T # clip new[:, [0, 2]] = new[:, [0, 2]].clip(0, width) new[:, [1, 3]] = new[:, [1, 3]].clip(0, height) # filter candidates i = box_candidates( box1=targets[:, 1:5].T * s, box2=new.T, area_thr=0.01 if use_segments else 0.10, ) targets = targets[i] targets[:, 1:5] = new[i] return im, targets def copy_paste(im, labels, segments, p=0.5): # Implement Copy-Paste augmentation https://arxiv.org/abs/2012.07177, # labels as nx5 np.array(cls, xyxy) n = len(segments) if p and n: h, w, c = im.shape # height, width, channels im_new = np.zeros(im.shape, np.uint8) for j in random.sample(range(n), k=round(p * n)): l, s = labels[j], segments[j] box = w - l[3], l[2], w - l[1], l[4] ioa = bbox_ioa(box, labels[:, 1:5]) # intersection over area if (ioa < 0.30).all(): # allow 30% obscuration of existing labels labels = np.concatenate((labels, [[l[0], *box]]), 0) segments.append(np.concatenate((w - s[:, 0:1], s[:, 1:2]), 1)) cv2.drawContours( im_new, [segments[j].astype(np.int32)], -1, (255, 255, 255), cv2.FILLED, ) result = cv2.bitwise_and(src1=im, src2=im_new) result = cv2.flip(result, 1) # augment segments (flip left-right) i = result > 0 # pixels to replace # i[:, :] = result.max(2).reshape(h, w, 1) # act over ch im[i] = result[i] # cv2.imwrite('debug.jpg', im) # debug return im, labels, segments def cutout(im, labels, p=0.5): # Applies image cutout augmentation https://arxiv.org/abs/1708.04552 if random.random() < p: h, w = im.shape[:2] # image size fraction scales = [0.5] * 1 + [0.25] * 2 + [0.125] * 4 + [0.0625] * 8 + [0.03125] * 16 for s in scales: mask_h = random.randint(1, int(h * s)) # create random masks mask_w = random.randint(1, int(w * s)) # box xmin = max(0, random.randint(0, w) - mask_w // 2) ymin = max(0, random.randint(0, h) - mask_h // 2) xmax = min(w, xmin + mask_w) ymax = min(h, ymin + mask_h) # apply random color mask im[ymin:ymax, xmin:xmax] = [random.randint(64, 191) for _ in range(3)] # return unobscured labels if len(labels) and s > 0.03: box = np.array([xmin, ymin, xmax, ymax], dtype=np.float32) ioa = bbox_ioa(box, labels[:, 1:5]) # intersection over area labels = labels[ioa < 0.60] # remove >60% obscured labels return labels def mixup(im, labels, im2, labels2): # 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) return im, labels # box1(4, n), box2(4, n) def box_candidates(box1, box2, wh_thr=2, ar_thr=20, area_thr=0.1, eps=1e-16): # Compute candidate boxes: box1 before augment, box2 # after augment, wh_thr (pixels), aspect_ratio_thr, area_ratio w1, h1 = box1[2] - box1[0], box1[3] - box1[1] w2, h2 = box2[2] - box2[0], box2[3] - box2[1] # aspect ratio ar = np.maximum(w2 / (h2 + eps), h2 / (w2 + eps)) # candidates return (w2 > wh_thr) & (h2 > wh_thr) & (w2 * h2 / (w1 * h1 + eps) > area_thr) & (ar < ar_thr)