Re: [Sugar-devel] [ASLO] webcam images and control
On Thu, Feb 25, 2010 at 03:39:26PM +0100, Emmanuel Di Folco wrote: Dear all, I am developing pedagogical activities using the integrated webcam of the XO laptop. My project aims at taking images of the Moon, by fixing a small scope in front of the webcam. I am now facing the following problems: - images are saturated because there is an automatic adjustment of the gain (or of the camera integration time ?) - images are compressed (JPG) and hence of very poor quality I am using the Record activity to make the images. I would like to be able to : - control the gain or integration time of the camera (mode Photo, not video) in order not to saturate (this is obviously feasible, since the images taken during the day are not saturated !) - eventually restrict the size of the screen window that is considered by the 'automatic gain adjustment algorithm' (where I would insert the moon) - gather the raw images, not the JPG compressed ones. Did you considered using gstreamer directly in your activity to capture images in format you need? Could any one help me ? Thanks in advance best regards, E. Di Folco CEA + La Main a la pate (France) ___ ASLO mailing list a...@lists.sugarlabs.org http://lists.sugarlabs.org/listinfo/aslo -- Aleksey ___ Sugar-devel mailing list Sugar-devel@lists.sugarlabs.org http://lists.sugarlabs.org/listinfo/sugar-devel
Re: [Sugar-devel] [ASLO] webcam images and control
Aleksey Lim wrote: On Thu, Feb 25, 2010 at 03:39:26PM +0100, Emmanuel Di Folco wrote: I would like to be able to : - control the gain or integration time of the camera (mode Photo, not video) in order not to saturate (this is obviously feasible, since the images taken during the day are not saturated !) - eventually restrict the size of the screen window that is considered by the 'automatic gain adjustment algorithm' (where I would insert the moon) The automatic gain adjustment is performed in hardware, not software. In the standard mode, the CPU has no control over the camera's gain/exposure time. It may be possible to put the camera into a manual mode, where the CPU can control gain and other parameters, but I do not know how to do this. The best person to ask is Jonathan Corbet, who wrote the camera's driver. However, the camera's interface has proven difficult to work with and poorly documented, so many advanced functions have not been implemented in the driver. On the XO-1.5, even basic camera functionality is still not working correctly. - gather the raw images, not the JPG compressed ones. I did manage to do this on the XO-1. You can try the instructions from: http://lists.laptop.org/pipermail/devel/2008-February/011029.html This code also controls the integration time by acquiring many images and averaging them. --Ben signature.asc Description: OpenPGP digital signature ___ Sugar-devel mailing list Sugar-devel@lists.sugarlabs.org http://lists.sugarlabs.org/listinfo/sugar-devel
Re: [Sugar-devel] [ASLO] webcam images and control
Jonathan Corbet wrote: All of the standard parameters are controllable through the normal V4L2 interface; that includes gain, saturation, etc. It all works. Fantastic; thank you. That sounds like big progress since the last time I looked at this ... two years ago. I guess it's time to take another look at a high-quality photography activity. On the XO-1.5, even basic camera functionality is still not working correctly. I'm looking at the flip issue today. What other basic functionality is not working correctly? I haven't been involved with this, so I can only speculate. #9853 suggests that the automatic gain control on XO-1.5 is not functioning as well as on the XO-1. I'm sure you know more about this than I do. --Ben signature.asc Description: OpenPGP digital signature ___ Sugar-devel mailing list Sugar-devel@lists.sugarlabs.org http://lists.sugarlabs.org/listinfo/sugar-devel
