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From: Aaron Wetzler on 25 Feb 2010 13:52
Hi
I have a Look316 webcam and I am running Matlab 7.9 on a computer with Windows 7.
My problem is that the properties of the camera that I need to access are not supported by the available adaptor for that camera which is 'winvideo'.

So for example I want to be able to change the Gain, Saturation, Gamma etc but the only feature available for changing is the FrameRate.

This makes no sense because the driver itself comes with software for editing these very details through the supplied AMcap.exe program that is called when clicking the photocapture button on the camera.

So, my question: How do I access embedded camera properties that are not supported by the adaptor that is connecting to my camera?

HELP!

(My only other option will be to download the directx amcap code and wrap it up and interact with that through Matlab but that seems serious serious overkill when i know for a fact that those properties are supported in other adaptors...)
From: Mark Jones on 3 Mar 2010 08:02
Hi Aaron,

Some vendor drivers do not expose the properties in such a way as they
can be controlled programmatically. This is very likely the case here.
We have several Logitech cameras here and all of them support
programmatic control. We do not recommend any brand of hardware, but I
can tell you that several Logitech cameras do work in the way that you need.

For example, I have a very old Logitech QuickCam Express camera and what
I can see in MATLAB is:

Device Specific Properties:
BacklightCompensation = on
Brightness = 5000
Contrast = 5000
FrameRate = 14.9999
Gamma = 2200
HorizontalFlip = off
Hue = 5000
Saturation = 5000
Sharpness = 5000
VerticalFlip = off
WhiteBalance = 5000
WhiteBalanceMode = auto

There are several options for you, each with different resulting
resolution time or likelihood:

1. Consider trying a different brand of camera

2. Contact the camera vendor and ask them to expose the properties in a
way that can be controlled programmitically without the dialog. We can
help them with knowing what is necessary in this regard if they contact
us. They may or may not be able to do this in the time frame that you need.

3. Contact our technical support and ask them to put in an enhancement
request for you to allow for you to have a way to bring up the dialog to
control the camera properties that are not accessible programmatically.
This is something that does come up periodically, and so it is
something that we can consider doing in a future release (the priority
has to be based on demand for all features that we have identified as
needed and/or have been asked for). In fact, I will ask them to contact
you and do all of this for you.

4. Consider writing a MEX file based on the AMCAP source code to bring
up the dialog. IF (and only if) the driver allows the dialog to be
brought up while the VIDEOINPUT object has a connection to the camera
already, then it might be possible to control the acquisition using the
VIDEOINPUT object and the properties using the dialog. It might even be
possible to do this using the vendor supplied software (and not write
any C/C++ code in a MEX file), however most vendor supplied software
locks the camera so that MATLAB is unable to connect to the camera at
the same time (so we often recommend closing the vendor supplied
software before attempting to create the VIDEOINPUT object, otherwise
MATLAB cannot access it).

Mark


Aaron Wetzler wrote:
> Hi
> I have a Look316 webcam and I am running Matlab 7.9 on a computer with
> Windows 7.
> My problem is that the properties of the camera that I need to access
> are not supported by the available adaptor for that camera which is
> 'winvideo'.
>
> So for example I want to be able to change the Gain, Saturation, Gamma
> etc but the only feature available for changing is the FrameRate.
>
> This makes no sense because the driver itself comes with software for
> editing these very details through the supplied AMcap.exe program that
> is called when clicking the photocapture button on the camera.
>
> So, my question: How do I access embedded camera properties that are not
> supported by the adaptor that is connecting to my camera?
>
> HELP!
>
> (My only other option will be to download the directx amcap code and
> wrap it up and interact with that through Matlab but that seems serious
> serious overkill when i know for a fact that those properties are
> supported in other adaptors...)
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