将C ++ opencv IplImage imageData和widthStep转换为android opencv Mat

Question

I'm developing an android app using opencv. I have an algorithm written in C++ which uses opencv and I am porting it to java. The original code uses 'IplImage' but now I'm forced to use 'Mat'. I managed to convert most of the code but I'm facing a problem with the following instructions:

IplImage *src;
src->imageData;
src->widthStep;

Can I use

[JAVA - Mat]src.dataAddr()  as an equivalent for [C++ - IplImage]src ->imageData

and

[JAVA - Mat]src.step1(0) as an equivalent for [C++ - IplImage]src->widthStep ?

The only link I found inherent to this topic is this one which explains how to convert 'IplImage' to 'Mat' but still in C++. I can't use javacv.

Thanks

Answer 1

For depth, Mat class has a method depth() .

The widthStep is a little tricky, because the step of Mat is not exactly the same as the widthStep in IplImage, but the multiple-of-four widthStep does not seem to be needed anymore. Here is an interesting answer to read. That said, Mat class also has a method for getting the step .

About imageData , I am not sure what exactly the imageData of IplImage contained, but with Mat, you can get data from of individual pixels by looping through the matrix and using methods like get(int row, int col) . Go through the documentation of Mat . I am sure you will get many options.

In the start of the doc, there is a discussion about IplImage and Mat and how the data is saved in Mat vs that in IplImage. Search for

So, the data layout in Mat is fully compatible with CvMat, IplImage, and CvMatND types from OpenCV 1.x.

and read around it.

Also read around

Partial yet very common cases of this user-allocated data case are conversions from CvMat and IplImage to Mat. For this purpose, there are special constructors taking pointers to CvMat or IplImage and the optional flag indicating whether to copy the data or not.