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Running
on
T4
| import cv2 | |
| import numpy as np | |
| def letterbox(img, new_shape=(640, 640), color=(114, 114, 114), auto=True, scale_fill=False, scaleup=True): | |
| # Resize image to a 32-pixel-multiple rectangle https://github.com/ultralytics/yolov3/issues/232 | |
| shape = img.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 test 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, 64), np.mod(dh, 64) # 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 | |
| img = cv2.resize(img, 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)) | |
| img = cv2.copyMakeBorder(img, top, bottom, left, right, cv2.BORDER_CONSTANT, value=color) # add border | |
| return img, ratio, (dw, dh) | |