As I mentioned my platform is limited to USB 1.1. I'm now using a Logitech 
Quickcam Pro 9000 and like most webcams it offers less functionality in USB 1.1 
mode. It only offers 160x120 in YUV mode and upto 800x600 in MJPG mode. The 
image quality appears to scale with the max requested framerate. 800x600 @ 5fps 
produces reasonable images but if possible I like to get better image quality. 
Increasing the fps reduces image quality as more compression is used to squeeze 
all the data over the bus.

If I would use still image the timing / buffering constraints would get 
relaxed, would I able to reach a higher resolution that way?

Roderick

-----Original Message-----
From:   Laurent Pinchart [mailto:[EMAIL PROTECTED]
Sent:   Wed 4/16/2008 10:42 PM
To:     [email protected]
Cc:     Colenbrander, Roderick; Brandon Philips
Subject:        Re: [Linux-uvc-devel] High resolution webcam + USB 1.1 (LX832)

On Wednesday 16 April 2008, Colenbrander, Roderick wrote:
> I read about the still image mode before but is it really anything special?
> Some sources indicate that it just grabs a frame from the video stream. The
> request is either made by the webcam software or by pressing a snapshot
> button. Sure I can program but is it worth all the troubles? The main
> advantage would be improved image quality.

It all depends on the hardware. The UVC spec defines several method to capture 
still images. The most common one, implemented by all the webcams I've tested 
so far, is to take the next image from the video stream. This won't help 
improving image quality.

Best regards,

Laurent Pinchart



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