How to create a Mat for 32 bit ARGB image

Mat
argb

asked 2013-02-22 03:23:47 -0600

samir22
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updated 2013-02-22 08:04:36 -0600

Andrey Pavlenko
1808 ●3 ●18 ●39

Hello,

I have a parallel thread running here about my troubles with using camera buffers to initialize a Mat. That thread has gotten all mixed up so I am creating a fresh thread to ask only one question.

How can 32 bit ARGB buffers be used to initialize a Mat. I found some references to using the BitmapToMat function but that appears to be available only under Android.

I am on a platform without an official port of OpenCV so a lot of OS level work (reading and writing images) is being done by hand.

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answered 2013-02-22 08:02:54 -0600

Andrey Pavlenko
1808 ●3 ●18 ●39

I assume your camera provides frame as an uchar* buff where A,R,G,B values of type uchar for one pixel are placed sequentially. Then the Mat initialization should look something like this:

int w, h;     // picture width and height
ucnar* buff;  // w*h*4 bytes, no strides between image lines
// ...
Mat m(h, w, CV_8UC4, buff);

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I cannot initialize with the buffer data directly because there is no guarantee that the data will remain in the buffer. So I'm copying it using memcpy and ptr()