Hi Sebatian, On 25 Oct 2010, at 15:28, sebaroc...@gmail.com 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 <bmsch...@fas.harvard.edu> > 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 <br...@laptop.org> > 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 <o...@spongezone.net> 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 <jeff.kel...@gmail.com> 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 <s...@laptop.org> 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 <br...@laptop.org> 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 >>>>>> <bmsch...@fas.harvard.edu> 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 >>>>>> Devel@lists.laptop.org >>>>>> http://lists.laptop.org/listinfo/devel >>>>>> >>>>> >>>> >>> >> > _______________________________________________ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel