[OLPC-GSoC] Gsoc Digest, Vol 4, Issue 10

Greg Smith gregsmitholpc at gmail.com
Thu Jun 26 14:57:15 EDT 2008

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
> Message-ID:
> 	<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.
> cam.start()
> frame = cam.get_image() # the frame returned is a 24bit pygame Surface
> You can also do fun stuff like:
> http://eclecti.cc/bytes/living-pointillism-a-pygame-webcam-script
> 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.
> Thanks,
> Nirav Patel
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> End of Gsoc Digest, Vol 4, Issue 10
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