Re: imaqhwinfo without gain parameters from NI-imaq
- From: "JGS " <jos.no.spam.grooteschaarsberg@xxxxxx>
- Date: Wed, 5 Dec 2007 08:18:26 +0000 (UTC)
Dave Tarkowski <dave.tarkowski@xxxxxxxxxxxxx> wrote in
message <fin1t6$2hk$1@xxxxxxxxxxxxxxxxxx>...
Since Camera Link is a digital interface, most CameraLink frame
grabbers do not have a gain parameter. If you want toadjust the "gain"
you can just multiply the resulting image data bywhatever your
coefficient of gain is. For analog frame grabbers thegain is typically
applied to the analog signal before digitization so thereis some
benefit to having a gain parameter.grabbers support.
The exposure property is not a property that frame
Exposure is a function of the camera, not of the framegrabber. By the
time the signal has made it to the frame grabber (eitheranalog or
digital) the sensor has already been exposed.to control
Camera Link does provide a serial interface to allow you
camera parameters. I do not remember how the NationalInstruments
Camera Link frame grabbers expose their serial ports. Ifthey are added
as virtual COM ports, you can use the SERIAL command inMATLAB to
communicate with the camera via the frame grabber.You'll have to look
up the command for changing the exposure in the camera'soperation manual.
-Dave Tarkowski
Hello Dave,
Thanks for the effort. So I am sorry to say that I have to
disagree partial with some of your answers.
With respect to the gain settings: I had 2 digital
interfaces: IEEE 1394 and Camera Link. Both have one
camera. And matlab Image Acquisition Toolbox gives access -
through its videoobject-source properties - to a gain
parameter for each of these. For one of these camera's I
have the manual that describes this camera property.
Additional I assume for both that it is a camera-internal
analog operation because a gain of 2 or 4 does still give
me a continuous histogram i.e. it is not-only a
multiplication by 2 or 4.
As I do not know how the previous user left me this camera,
I have to set this parameter. And probably I want to change
it from within matlab as part of measurement scripts.
With respect to the exposure: I fully agree that this is
mostly a camera-internal property. Although I know camera's
where you can apply a pulse-width signal for setting this
properties. But especially with these digital interfaces,
the commands for setting the exposure goes via the
interface. And supporting software should give easy access
to this setting.
With respect to progamming: I should be able to solve this
problem myself. And it would cost me a day. And for the
next interface another day. And the next... That is why we
selected to buy the image acquisition toolbox.
This toolkit works fine with the IEEE 1394 interface and
the attached camera. And this toolkit worked almost fine
with the previous camera link interface: however it was an
unsupported OEM that gave access to gain and exposure but
is was an unstable link between interface driver and matlab.
Therefore we bought the new camera link PCI-1426 interface
that is supported. And I already now that the driver with
this interface gives access to these parameters because the
quick-view tool (NI Measurement&Automation) allows me to
set these.
So there is still my question:
where can I find easy access in the Image Acquisition
Toolbox for setting these parameters when using using a
National Instruments camera link interface together with
driver NI-IMAQ 3.7.1 ?
Regards, Jos
.
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