Hi, I think it should be possible by using the v4l2 python bindings[1]. There are a few controllable knobs that the xo-1 camera provides (don't know if its the same on xo-1.5). These are:
1. AGC (Auto gain control) 2. Gain 3. Exposure 4. Brightness 5. Contrast 6. Saturation A typical python code for changing camera brightness would be [2] [1] http://pypi.python.org/pypi/v4l2 [2] http://dpaste.org/iSa7/ -- Anish P.S. I'm not sure if these settings are controllable directly through gstreamer. On Mon, Oct 25, 2010 at 9:04 PM, Gary C Martin <[email protected]> wrote: > > Hi Sebatian, > > On 25 Oct 2010, at 15:28, [email protected] wrote: > > > Hi, > > > > Im working on a computer vision project in the XO and i would like to > > disable the color balancing on the XO webcam but i don't know how. > > In this link http://wiki.laptop.org/go/Hardware_specification says that it > > is posible :) > > This reminded me of some distant email threads, here's a quick copy paste > from my archive of them, in case any are of help. > > Regards, > --Gary > > --- copy & paste 1 --- > > > From: Benjamin M. Schwartz <[email protected]> > > Subject: Re: [Sugar-devel] [ASLO] webcam images and control > > Date: 25 February 2010 16:46:29 GMT > > > > 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 > > > --- copy & paste 2 --- > > > From: Brian Jordan <[email protected]> > > Subject: Re: Panorama activity > > Date: 12 October 2008 06:39:45 GMT+01:00 > > > > On Sat, Oct 11, 2008 at 10:26 PM, Nirav Patel <[email protected]> wrote: > >> My roomate and I wrote an auto-stitching Panorama Activity during the > >> Yahoo Hack Day at CMU yesterday (ended up winning the Hack for Good > >> award). I'll be posting it in the wiki at some point today. It needs > >> a whole lot of polishing, since it was written in 24 hours. > >> > >> I ran into the same problem that Ben did with autowhitebalance and > >> autoexposure. I looked through the ov7670 driver, and it seems > >> changing V4L2_CID_BRIGHTNESS should flip the auto exposure control > >> (AEC) bit in one of the registers. I added support for changing > >> brightness to the camera module in Pygame, but either disabling AEC > >> doesn't work, or it just makes auto gain control and auto white > >> balance work even harder to change the image. Other than that, the > >> stitching seems to work ok. I'm going to pyramidize it at some point > >> to make it faster, and do something to improve the accuracy. The > >> slowness of stitching doesn't effect the user experience much though, > >> because it only stitches after the user is done taking the pictures. > >> > > > > So cool -- can't wait to try. > > > >> The Activity we wrote uses the Flickr API for an upload to Flickr > >> button. I feel that this is the most important part. There is > >> support for saving the stitched images as Journal entries, but it > >> would be wonderful if a kid anywhere in the world could see panoramas > >> taken by other kids elsewhere. Flickr is far from ideal for this. > >> Beyond not really being designed for viewing panoramas, it is > >> currently set up to just upload every picture to my personal Flickr > >> account. My API key, secret key, and an authentication token are > >> prerecorded in the activity, so anyone could potentially use those > >> values to edit existing photos and upload whatever to my Flickr > >> account: http://flickr.com/photos/nrpatel/ > >> > > > > Awesome! :-D > > > > Maybe one could set up a one-way upload script for this on dev (or > > some appropriate > > community-developed-web-services-server-of-the-future)? This script, > > then, could handle the uploading via flickr API securely. > > > > Regards > > Brian > > > >> It seems Gigapan doesn't have an upload API. gigapan.org works in > >> Browse on my os767 XO, but panning around an image is pretty slow. > >> Anyone have ideas on this? A better way to Flickr, ideas for > >> designing a new site, getting Gigapan to add an upload API, etc? > >> > >> The other issue we ran into is integrating OLPCGames with pyGTK stuff. > >> We used OLPCGames to take advantage of capturing the images as SDL > >> surfaces, but we also wanted pyGTK to pop up a Dialog box when the > >> user hits Save, asking for a Title, Tags, and a Description of the > >> panorama. We hacked together something that does pop up the box and > >> saves correctly, but fails to ever destroy the box. It then just sits > >> with the box open, preventing the user from using or exiting the > >> Activity. Is it possible to use pyGTK beyond the toolbox while still > >> using OLPCGames? > >> > >> Nirav > >> > >> On Fri, Sep 5, 2008 at 6:41 PM, Jeff Keller <[email protected]> wrote: > >>> Yeah -- I sent my loaner unit off to Burning Man, but I should get it > >>> back soon, and I'd be delighted to talk about stitchers. Randy > >>> Sargent and I wrote our own for GigaPan last summer because nothing > >>> else was up to the task. It relies on a model of the GigaPan device's > >>> behavior to do rough placement, but it can auto-stitch 1000+ images > >>> with < 10 pixels rms displacement error, and it should be open-sourced > >>> one of these days. Of course, it uses much more storage, RAM, and CPU > >>> than an XO has, but nothing inappropriate to what it does, and there > >>> are some nice improvements in the works. Oh, and my office is down > >>> the block from OLPC's. > >>> --Jeff > >>> > >>> On Fri, Sep 5, 2008 at 12:38 PM, Samuel Klein <[email protected]> wrote: > >>>> Speaking of which, Jeff Keller has been trying to get OLPC folks to > >>>> learn more about using his gigapan group's cameras (and perhaps to > >>>> borrow one to bring them into a country for weeks) for a while. Jeff, > >>>> Ben Schwartz and Nirav are really interested in large-scale image > >>>> splicing... > >>>> > >>>> SJ > >>>> --- > >>>> 617 529 4266 > >>>> > >>>> > >>>> On Fri, Sep 5, 2008 at 2:08 AM, Brian Jordan <[email protected]> wrote: > >>>>> *bump* > >>>>> > >>>>> http://wiki.laptop.org/go/Panorama_camera_activity > >>>>> > >>>>> (code? Nirav is interested in doing something similar!) > >>>>> > >>>>> Brian > >>>>> > >>>>>> On Wed, Jun 20, 2007 at 11:56 PM, Benjamin M. Schwartz > >>>>>> <[email protected]> wrote: > >>>>>> -----BEGIN PGP SIGNED MESSAGE----- > >>>>>> Hash: SHA1 > >>>>>> > >>>>>> The XO happens to be perfect for shooting stitched panoramic > >>>>>> photographs, due to > >>>>>> the swivel design. I tested it out in the OLPCHQ lobby. Then, I wrote > >>>>>> a simple > >>>>>> panorama stitcher in 50 lines of Python. It runs in 3.4 seconds on my > >>>>>> Core Duo, > >>>>>> producing this output: > >>>>>> > >>>>>> http://people.fas.harvard.edu/~bmschwar/lobby_ugly.jpg > >>>>>> > >>>>>> The results aren't too bad. I also tried stitching this scene with > >>>>>> Hugin, the > >>>>>> most powerful panorama stitcher I know of. Hugin required significant > >>>>>> user > >>>>>> intervention and half an hour of computing time, producing this output: > >>>>>> > >>>>>> http://people.fas.harvard.edu/~bmschwar/lobby_pretty.jpg > >>>>>> > >>>>>> This scene is unusually difficult because of the huge indoor-outdoor > >>>>>> contrast. > >>>>>> Given this positive result, I would like to work on a panorama-making > >>>>>> activity, > >>>>>> possibly inside Capture. I know that at age 10, I loved making > >>>>>> panoramas out of > >>>>>> photographs. Panoramas provide an immersive way for children to > >>>>>> communicate > >>>>>> their environments to each other and to the world. > >>>>>> > >>>>>> - --Ben Schwartz > >>>>>> -----BEGIN PGP SIGNATURE----- > >>>>>> Version: GnuPG v1.4.7 (GNU/Linux) > >>>>>> Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org > >>>>>> > >>>>>> iD8DBQFGeU4yUJT6e6HFtqQRAv4rAJ9F5wTDfzz9piYzzwGskVVmaqZTiQCgjFru > >>>>>> QsRergUtY1iCZS6hIXCHjSM= > >>>>>> =v5GB > >>>>>> -----END PGP SIGNATURE----- > >>>>>> _______________________________________________ > >>>>>> Devel mailing list > >>>>>> [email protected] > >>>>>> http://lists.laptop.org/listinfo/devel > >>>>>> > >>>>> > >>>> > >>> > >> > > > _______________________________________________ > Devel mailing list > [email protected] > http://lists.laptop.org/listinfo/devel -- Anish Mangal [email protected] _______________________________________________ Devel mailing list [email protected] http://lists.laptop.org/listinfo/devel
