Webcam exposure problems

January 22, 2006 2:27 PM

I am having overexposure problems with a webcam pointed outside. It's not pointed at the sky, and it overexposes even on rainy days. I think I need software that will do a better job.

The webcam in question is a Logitech QuickCam. I've seen this problem too with a Creative Labs webcam, so I'm wondering if this is endemic to all webcams.

* As I pointed out, this happens in any outdoor shot, even if it's cloudy outside. It seems that any scene brighter than indoor lighting gives it problems.

* By turning off Automatic Gain Control and lowering the exposure and gain, I can get pretty good outdoor shots. Of course these settings are useless once the illumination changes.

* I usually have Automatic Gain Control checked. When I open up a Preview window, the camera starts adjusting its settings and fixes the exposure. It's almost like I need the Webcam software to run a preview for 10 seconds so the exposure can get fixed.

* The big thing that is making this difficult is that all the webcam software I've tried opens up the very same Video Source settings panel. So programs like Dorgem, SupervisionCam, Spycam, etc seem to shun dealing with the camera, just acting as timer programs.

So is there any webcam software that will take control, bypass the generic device settings, and work with me to get better exposures?

posted by zek to computers & internet (3 comments total)

You might want to try adding a neutral density filter in front of the lens. You should be able to use google to find some suitable material, and just tape it in pace.
posted by b1tr0t at 4:18 PM on January 22, 2006

If the AGC is broken, adding an NDF most likely won't help because the AGC will just crank up the gain to compensate. Is there an "exposure compensation" field somewhere in the settings?

Due to the myriad cameras available, you have to depend on the drivers for the camera to actually control the camera. It's the same as per printers - you wouldn't expect Word to understand every model of printer in existence, it just loads a property form defined by the driver.
posted by polyglot at 7:55 PM on January 22, 2006

You need a camera with an adjustable or auto iris control. Just like when your eyes are acclimatized for inside it makes everything outside way too bright (and you have to squint to see anything), most webcams are designed for the low light levels of indoors and don't have the ability to "squint." That's where iris adjustments come in.

It may be cheaper to get decent results with an inexpensive video capture card and an auto-iris ccd camera with a standard video output than to monkey with usb offerings.
posted by BrandonAbell at 9:55 AM on January 23, 2006