Re: imaqhwinfo without gain parameters from NI-imaq

JGS wrote:
I can find a camera adapter and camera with matlab Image Acquisition Toolbox using a.o. imaqhwinfo. Next I can create an video-object using the ObjectConstructor. From this video-object I can ask for its Properties using the get-function. And finally one of these Properties is the Source with typical fields like Gain and Exposure values.
This works for several adapters, although the actual fieldnames for gain and exposure can differ.
I just updated to Image Acquisition Toolbox version 3.0 because this supports camera link interfaces from National Instruments with NI-IMAQ 3.7.1. I do get a connection, but I cannot find the camera parameters such as gain and exposure.
Where can I find and set camera gain and camera exposure from within matlab when using a NI-framegrabber with NI-
IMAQ 3.7.1 ?

Since Camera Link is a digital interface, most Camera Link frame grabbers do not have a gain parameter. If you want to adjust the "gain" you can just multiply the resulting image data by whatever your coefficient of gain is. For analog frame grabbers the gain is typically applied to the analog signal before digitization so there is some benefit to having a gain parameter.

The exposure property is not a property that frame grabbers support. Exposure is a function of the camera, not of the frame grabber. By the time the signal has made it to the frame grabber (either analog or digital) the sensor has already been exposed.

Camera Link does provide a serial interface to allow you to control camera parameters. I do not remember how the National Instruments Camera Link frame grabbers expose their serial ports. If they are added as virtual COM ports, you can use the SERIAL command in MATLAB to communicate with the camera via the frame grabber. You'll have to look up the command for changing the exposure in the camera's operation manual.

-Dave Tarkowski
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