How does the winvideo adaptor in Image Acquisition Toolbox exactly return YUY2 data in YCbCr colorspace?
5 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
MathWorks Support Team
am 18 Dez. 2017
Bearbeitet: MathWorks Support Team
am 26 Jan. 2023
I have a camera (Leopard USB camera LI-USB30-M021X) with winvideo compatible DirectShow driver which says it outputs images in YUY2 format. Now YUY2 is a format in which you normally use 16-bit per pixel to describe a color image. This camera does not actually capture color images though, in reality it captures 12-bit grayscale images which are then encoded into those 16-bits per pixel YUY2 format. Can I recover the original 12-bit data format in MATLAB somehow?
Akzeptierte Antwort
MathWorks Support Team
am 14 Dez. 2022
Bearbeitet: MathWorks Support Team
am 26 Jan. 2023
If you look at how YUY2 data is stored:
We see, that for the first 4 pixels, it looks like:
Where with the colors I have tried to indicate how I assume the camera vendor has encoded the 12-bit data as 2-bytes of data in YUY2.
If using videoinput with a YUY2 format and the default YCbCr ReturnedColorSpace, MATLAB then maps this data to a YCbCr image "im" in MATLAB in the following way:
Y0 = im(1,1,1)
U0 = im(1,1,2) = im(1,2,2)
Y1 = im(1,2,1)
V0 = im(1,1,3) = im(1,2,3)
Y2 = im(1,3,1)
U1 = im(1,3,2) = im(1,4,2)
Y3 = im(1,4,1)
V1 = im(1,3,3) = im(1,4,3)
Since there is no scaling or averaging going on, you should be able to access the original raw 12-bit data by combining the right elements again. i.e. to get Y0|U0 we need to take im(1,1,1) and combine it with im(1,1,2) where, depending on how the vendor encoded the data exactly in which order, one of those two should be shifted by 8 bits (= multiplying by 256). So then to get the first 12-bit value you would use:
v = uint16(ImageFrame(1,1,2))*2^8 + uint16(ImageFrame(1,1,1));
Similarly for Y1|V0 we would combine im(1,2,1) with im(1,2,3). Or for a whole 1280x720 image we should then be able to write:
A = zeros(720,1280,'uint16');
A(:,1:2:end) = uint16(ImageFrame(:,1:2:end,2))*2^8 + uint16(ImageFrame(:,1:2:end,1));
A(:,2:2:end) = uint16(ImageFrame(:,2:2:end,3))*2^8 + uint16(ImageFrame(:,2:2:end,1));
0 Kommentare
Weitere Antworten (0)
Siehe auch
Kategorien
Mehr zu Image Acquisition Support Packages for Hardware Adaptors (Generic Video Interface) finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!