PyTorch学习:对比CV2和PyTorch的预处理
作者:互联网
验证预处理一致性
import os
import cv2
import numpy as np
import PIL
import torch
from PIL import Image
import torchvision.transforms as transforms
class RGBToBGR():
def __call__(self, im):
assert im.mode == 'RGB'
r, g, b = [im.getchannel(i) for i in range(3)]
# RGB mode also for BGR, `3x8-bit pixels, true color`, see PIL doc
im = PIL.Image.merge('RGB', [b, g, r])
return im
class ScaleIntensities():
def __init__(self, in_range, out_range):
""" Scales intensities. For example [-1, 1] -> [0, 255]."""
self.in_range = in_range
self.out_range = out_range
def __oldcall__(self, tensor):
tensor.mul_(255)
return tensor
def __call__(self, tensor):
tensor = (
tensor - self.in_range[0]
) / (
self.in_range[1] - self.in_range[0]
) * (
self.out_range[1] - self.out_range[0]
) + self.out_range[0]
return tensor
def make_transform():
inception_sz_resize = 256
inception_sz_crop = 224
inception_mean = [104, 117, 128]
inception_std = [1, 1, 1]
inception_transform = transforms.Compose(
[
RGBToBGR(),
transforms.Resize(inception_sz_resize),
transforms.CenterCrop(inception_sz_crop),
transforms.ToTensor(),
ScaleIntensities([0, 1], [0, 255]),
transforms.Normalize(mean=inception_mean, std=inception_std)
])
return inception_transform
def cv2_transform(image):
inception_sz_resize = 256
inception_sz_crop = 224
inception_mean = [104, 117, 128]
inception_std = [1, 1, 1]
image = cv2.resize(image, (inception_sz_resize, inception_sz_resize),interpolation=cv2.INTER_LINEAR)
#image = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
image = image[16:16+224,16:16+224]
image = image.astype(np.float32)
image = image - inception_mean
image = image / inception_std
image = image.transpose((2, 0, 1))
return image
if __name__ == '__main__':
inception_transform = make_transform()
image_name = r"./test.jpg"
im = PIL.Image.open(image_name)
result = inception_transform(im)
result = result.numpy()
print('result:',result.shape)
image = cv2.imread(image_name,-1)
result2 = cv2_transform(image)
print('result2:',result2.shape)
结论:
不加Resize和中心裁剪操作,两者一样;
加了Resize和中心裁剪操作,结果基本一致,不影响实际使用;
标签:__,cv2,image,CV2,PyTorch,self,range,inception,预处理 来源: https://blog.csdn.net/u013841196/article/details/121563944