View Full Version : White Balance shift after LiveStop

December 9, 2002, 00:36:29
I've run into a strange problem that only seems to manifest itself if the camera is viewing an all white frame (in my case I am sampling ink on paper and using the white paper to set my white balance):

What is happening is that if I perform a LiveStop then a LiveStart, the white balance seems to shift to blue. I am adjusting white balance via the "one-push" method. WB values read back from IC is Red: 255 Blue: 66, prior to and after the stop/start sequence, so it doesn't appear that the white balance values are changing.

All auto properties are set false.

I can reproduce the effect in the samples "Sonydemoapp" and "Sonydcamvb" by stopping then restarting a preview.

I can reproduce the effect in the Sony supplied apps "Sonycap" and "Amcap" only by going back into Options->VideoCapturePin and either canceling or chhosing another Video Format, then clickng "OK". Starting and stopping a preview does not cause the blue shift.

I am using IC 1.4 SP2 with a Sony DFW-V500 and have installed the Sony Add-on. OS is Windows 2000 SP3 and VB6 SP5 is the language.

Any idea what might be happening?

I'm also curious why Red never is below 255 on all my white balances (auto or one-push), could this be my light source (5600K) ?

This message was originally posted by Jeff Fayne in the old IC Imaging Control Support Forum.

December 10, 2002, 15:51:23
Hello Jeff,

Under certain circumstances, the Sony WDM driver changes the white balance values. Sometimes they will be moved outside the range from 0 to 255. In this case, the one push button and the automatic white balance will not work any more.
To avoid shifting of the white balance, you should calibrate the white balance and save the values for red and blue before calling stop the live video. After you have started the live video, your application should set the previously saved white balance values to the white balance. The white balance values can be set, even if the live video runs. The Sony DCAM Demo application saves and loads the property values of the camera.

Best regards
IC Support

This message was originally posted by IC Support in the old IC Imaging Control Support Forum.