I want to read and modify some pixels in my matrix. How can I do that in Java? Is there any equivalent for the C++ Mat::at method?
In Java you can use
One pixel can be read by
double Mat::get(int row, int col)
One or few pixels can be written by
Mat::put(int row, int col, double... data)
But if you're going to work with many pixels, it's better to get all the Mat data at once to Java primitive array, work with it in Java, and then put it back to Mat with a single JNI call. The corresponding Java primitive array type depends on the Mat type:
CV_8U and CV_8S -> byte, CV_16U and CV_16S -> short, CV_32S -> int, CV_32F -> float, CV_64F-> double.
So the code will look like following:
Mat m = ... // assuming it's of CV_8U type byte buff = new byte[m.total() * m.channels()]; m.get(0, 0, buff); // working with buff // ... m.put(0, 0, buff);
Asked: 2012-06-08 08:47:00 -0500
Seen: 26,773 times
Last updated: Jun 08 '12