OpenCV 3.x, 4.x no more support `IplImage`, some codes should be modified.

[Huixxi]

If you want to compile and run those code with a higher version opencv(opencv 3.x+), you should change the following lines of code:

PCANet/cpp_version/main.cpp

Lines 52 to 57 in d48d888

	img = cvLoadImage(path, CV_LOAD_IMAGE_GRAYSCALE);
	change = cvCreateImage(cvGetSize(img), IPL_DEPTH_64F, img->nChannels);
	cvConvertScale(img, change, 1.0/255, 0);
	bmtx = new cv::Mat(change);
	InImgs.push_back(*bmtx);

with:

cv::Mat img = cv::imread(path, CV_LOAD_IMAGE_GRAYSCALE);
img.convertTo(img, CV_64F, 1.0 / 255.0);
		
InImgs.push_back(img);

[Ldpe2G]

@Huixxi thanks for your advice