Python notes: multiple pictures are stored in the list and displayed after calling

When implementing some function processing functions, sometimes batch images are processed, and the processed images are expected to be passed to another function for processing, and multiple images are used as return values. A list is required to store these images as parameters and pass them to another function. a function.
When I first checked this on the Internet, I saw that it was, images = [[], []] * images_numbut there was always an error in the final output TypeError: Expected Ptr<cv::UMat> for argument 'mat'. Check the output of the images list, the empty list

List after saving image data

The image is stored in matrix mode, images = [[]]*images_numjust set the list as directly.

def f1():
	images = [[]] * images_num 
	for i in range images_num:
	 # 此处省略处理过程，img为处理后的图像
		images[i] = img 
	return images

All functions can be temporarily stored in a list as return values. If you put return in the for loop, only the first image data will be returned.

def f2():
	# 调用函数f1
	images = f1()
	# 显示图像，可以直接使用imshow函数，不需要使用imread读取
	for img in images:
		cv2.imshow(‘img’, img)
		cv2.waitKey(100)