Archive for January, 2011


Seeing Red

Unfortunately, due to the @!#$ internet connection, this blog post was, unfortunately, lost. Anyway, the jist of the post was that not much has been done since the last post, and work is proceeding at a snail’s pace. Also, a major error was detected and rectified wherein I had naively set the hue ranges to {1,180} rather than {0,180} because of the spike in the red colour in the Histogram. That, in turn, was because of the fact that the black background of the image (I simply extract the features of interest and place them on a blank image) , when transformed to the HSV colour space came up as hue 0, or Red. So, fixed it by using the mask to calculate the Histogram, and all was good.

The next thing to do is implementing the back propagation neural network. What’s been figured out is that the test images from the public database have to be scaled down to a smaller resolution – say 16×16, fed to some arbit number of hidden layer neurons, and then five output neurons, as we require 5 bits of information (26 letters + 10 digits).

I end, as the original post did, with – This is going to be one busy semester.

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Cam-era Part II

First of all, a very happy New Year!

Right, now that we’re done with the niceties, moving on to the update, I have now managed to capture pictures from the camera through the USB cable on the beagleboard and transfer the images to my computer using a script running on the beagleboard. I use the gphoto2 command line interface and a simple hook script which rsync’s with a folder on my computer over the network. To avoid the password hassles I created a public key on the beagle and added it to the authorized_keys file in ~/.ssh/ (Of course there aren’t any security issues – Only I use the beagleboard)

However, the delay between consecutive pictures is quite significant (I timed it to ~3.6 seconds between snaps) and it is to be seen whether it would be adequate or not. (I feel that it won’t) I tried setting the mode to fixed aperture, landscape modes, etc. so that it doesn’t waste precious seconds on autofocussing, but no dice. Changing image resolution also didn’t help. So the only alternative seems to take pictures in burst mode and then transferring them. The trigger will have to be done via video(?), and there will be a massive delay between consecutive burst pics. The low resolution for such pictures isn’t too good a thing either. Another mode that the camera supports is a 5 second continuous shot buffer, but it is still to be seen if I can access the buffer on the fly (It seems unlikely though)

So, as matters ┬ástand, unless a DSLR is used, it’s going to be tough trying to get high resolution snaps at short time intervals. Sad, but anyway, let’s save the verdict for the flight test.