[OLPC-GSoC] Gsoc Digest, Vol 4, Issue 10
bobbypowers at gmail.com
Thu Jun 26 15:07:43 EDT 2008
Dan and Eric spent some time yesterday looking at video issues, they
might have suggestions.
On Thu, Jun 26, 2008 at 2:57 PM, Greg Smith <gregsmitholpc at gmail.com> wrote:
> Hi Nirav,
> A few off the cuff suggestions.
> Only design it for the built in camera. That's all 99% of the kids will
> I can't tell where your performance bottle neck is from this e-mail but
> one suggestion is to pick one format and optimize for it and only it.
> YUV420 is my favorite but whatever gives the best peformance you only
> need one.
> Make a sample/demo application. Build it all the way to .XO format and
> post it to the supported activities page.
> Image recognition and that kind of processing is interesting but its
> very tough to get right and hard to understand what its doing.
> Image processing where you modify what you see in the screen is easier
> and may be more fun for the kids. e.g. sepia, color, black and white,
> swirl, "special effects" in general. I'm not sure if that falls in your
> area but I think the kids will really enjoy that if you can do it.
> If you can save those effects to file or modify files in that way you
> are getting close to video editing. Which I think would be super useful!
> That's my 2 cents. Get me an installable activity to show what your are
> talking about and I'll invite some teachers and kids to try it out make
> suggestions on what else they would like to see...
> Greg S
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>> Today's Topics:
>> 1. GSoC Status Report: Vision Processing (Nirav Patel)
>> Message: 1
>> Date: Thu, 26 Jun 2008 17:07:00 +0900
>> From: "Nirav Patel" <nrpatel at gmail.com>
>> Subject: [OLPC-GSoC] GSoC Status Report: Vision Processing
>> To: sugar at lists.laptop.org, devel at lists.laptop.org,
>> gsoc at lists.laptop.org
>> <a7215bb70806260107k76d12f6cs1dc6d6687d40b31 at mail.gmail.com>
>> Content-Type: text/plain; charset=ISO-8859-1
>> As you may know, OLPC got GSoC students again this summer. I am one
>> of them, and my project is Vision Processing. That is, a library to
>> use the webcam for more than capturing images. I am implementing this
>> by adding v4l2 and computer vision functions to pygame.
>> My code is available at http://git.n0r.org/?p=pygame-nrp;a=summary and
>> is currently pygame 1.8.1 with the addition of a camera module that
>> supports v4l2 cameras that use MMAP and have pixelformats of RGB24,
>> RGB444, YUYV, SBGGR8, or YUV420. Basic usage is as follows:
>> import pygame
>> from pygame import camera
>> cam = camera.Camera("/dev/video0", (640, 480), "RGB") # the third
>> argument can be YUV or HSV too.
>> frame = cam.get_image() # the frame returned is a 24bit pygame Surface
>> You can also do fun stuff like:
>> or more practical stuff like having it track the centroid of a
>> specific hue (green in this case): http://eclecti.cc/files/centroid.py
>> My plans are to add functions like finding the largest connected
>> component, optical flow, and other things useful for computer vision.
>> Currently, performace is pretty poor on the XO; a combination of the
>> Geode being slow and having to convert from 24bit to 16bit surfaces to
>> display any captured frames. The XO is fast enough to capture and
>> blit a 320x240 RGB frame at 30fps, but not at 640x480 or a frame being
>> converted to HSV. I'm not sure how or if I'm going to be able to
>> overcome those performance problems.
>> I'd appreciate any comments, suggestions, or reality checks on
>> improving performance or anything else, or any requests for vision
>> functions to add. Also, I only have the camera in the XO, vivi, and a
>> poorly supported USB webcam, so if anyone could test it on other
>> webcams, that would be great.
>> Nirav Patel
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>> End of Gsoc Digest, Vol 4, Issue 10
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