OpenCV's Java bindings Mat.get() gives weird results [closed]
I have a 8UC1 Mat image. I'm trying to convert it to Java 2D byte array with [x][y] coordinates. Here's what I have so far:
byte[][] arr = new byte[mat.cols()][mat.rows()];
for (int colIndex = 0; colIndex < mat.cols(); colIndex++) {
mat.get(0, colIndex, arr[colIndex]);
}
However, that gives me totally scrambled results. For example a mat with .dump() such as this:
[255, 255, 255, 255, 255, 255, 255, 255, 255, 255;
0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
255, 255, 255, 255, 255, 255, 255, 255, 255, 255;
255, 255, 255, 255, 255, 255, 255, 255, 255, 255;
255, 255, 255, 255, 255, 255, 255, 255, 255, 255]
gives me this (don't mind the -1, that's OK):
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 0
-1 -1 -1 -1 -1 -1 -1 -1 0 0
-1 -1 -1 -1 -1 -1 -1 0 0 0
-1 -1 -1 -1 -1 -1 0 0 0 0
oh wait, pixels are stored in a 1D byte[] array, not a 2D [][] one.
try:
or , if you are interested in a single pixel only:
This is not what i want. I want to create a 2D array.
"I want to create a 2D array." - sorry, you must not. please understand, that the underlying c++ api is working on consecutive data, not on pointers to an array per row.
I don't see your point. That is one of the reasons I want to create the 2D array. I must convert it, so I can work with it easily in Java, without the sluggish JNI calls to individual pixels.
Well I recognise that, that's why I made this question in the first place. So the bottom line is you don't know why the provided code doesn't work?
apologies, misread your question.
it is
mat.get(row,col)in opencv, not x,y. so you need:mat.get(colIndex, 0, arr[colIndex]);