How to unpack mono12packed data images from preview

Hello,

I am using the image acquisition tool to control a camera and I would like to know how to use preview properly when the camera is streaming mono12packed data.

For exemple if I set the camera to 8 bit with the following code I get nice images as shown here :

main_cam = videoinput('gige','1','Mono8');
preview(main_cam)
stoppreview(main_cam)

But if I set the camera to mono12packed I get data that seems unpacked too me :

delete(main_cam)
main_cam = videoinput('gige','1','Mono12Packed');
preview(main_cam)
stoppreview(main_cam)

I have the same unpacked data issue when using getdata like this :

main_cam = videoinput('gige','1','Mono12Packed');
start(main_cam)
[img,time_main]    = getdata(main_cam,1,'double','cell');
imagesc(img{1})

Do you have ideas on how to get unpacked data from preview and getdata ?

Thank you very much !

Answer 1

[Walter Roberson]

https://www.mathworks.com/help/imaq/returnedcolorspace.html

[Matt]

Hi,

The colorspace is by default set to 'grayscale' as it should.

The thing is that in mono12packed the value of 2 pixels is written on two consequtives bytes as explained in this link.

I would expect getdata to know how to deal with this but it seems that no. When asking getdata to get data in the native format I get unint16 data where the work to unpack data (ie for each pixel go get 8 bites in the Nth byte and 4 bites in the N+1th byte for exemple and store them in a uint16 where the 4 first bites are 0) has not been done.

getdata(main_cam,1,'native','cell') % get me uint16 data