Python & PIL - Revision history

Bbogart at 21:22, 6 December 2006

2006-12-06T21:22:27Z

← Older revision		Revision as of 21:22, 6 December 2006
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	I wrote two python programs for:		I wrote two python programs for:

	* Controlling ffmpeg to batch process the ripped VOB fiels into jpgs [~~[Media~~:~~Example~~.~~ogg]~~]		* Controlling ffmpeg to batch process the ripped VOB fiels into jpgs [http://www.sfu.ca/~bbogart/csi/vob2frame.py src]

	* Image Processing [~~[Media~~:~~Example~~.~~ogg]~~]		* Image Processing [http://www.sfu.ca/~bbogart/csi/processFrames-PIL.py src]

Bbogart at 21:19, 6 December 2006

2006-12-06T21:19:28Z

← Older revision		Revision as of 21:19, 6 December 2006
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	# Writes the mean value of the pixels in the image to a logfile.		# Writes the mean value of the pixels in the image to a logfile.

	I ~~solved~~ two ~~problems in~~ python:		I wrote two python programs for:

	* Controlling ffmpeg to batch process the ripped VOB fiels into jpgs [[Media:Example.ogg] ~~source~~]		* Controlling ffmpeg to batch process the ripped VOB fiels into jpgs [[Media:Example.ogg]]

	* Image Processing [[Media:Example.ogg] ~~source~~]		* Image Processing [[Media:Example.ogg]]

Bbogart at 21:18, 6 December 2006

2006-12-06T21:18:43Z

New page

I had planned to do the computer vision aspect of this project with python-opencv (The python hooks into the Open Computer Vision library). I ended up abadoning this method because OpenCV does not have any simple tracking (center of gravity of moved pixels in the frame) only complex tracking. I looked at CAMShift and MHI algorithms. The CAMShift tracking the colour mean of an image, MHI is a motion history image that calculates vectors of motion in the image based on a gradient from old to new frames. Both these methods (and opencv in general) work best with static cameras, so these methods get total lost when there is a scene cut.

In order to get data more quickly after a month of work on opencv I decided to look at the Python Imaging Library (PIL) which gives you a nice number of functions for working with image files. This is not a real-time image processing library, though it is quite fast considering. PIL has not computer vision facilities built in. I ended up doing a very simple process where the program:

# Opens an image file.
# Opens the previous file in the sequence.
# Removes the colour data from the images
# Subtracts the two frames to get the difference
# Writes the mean value of the pixels in the image to a logfile.

I solved two problems in python:

* Controlling ffmpeg to batch process the ripped VOB fiels into jpgs [[Media:Example.ogg] source]

* Image Processing [[Media:Example.ogg] source]