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IMAGE PROCESSING FUNDAMENTALS

Part 2: Math, Math, Math

by James Antonakos

Start ý Blob Analysis ý Edge DetectionýBehind the Mask ý A Helping Hand from Fourier ý Please Sir, May I Have Some More? ý Sources and PDF

This month, Iýll continue discussing the many interesting operations that can be performed on an image. Of course, there will be a lot of math involved in the operations discussed, so get ready for some real thrill seeking as I delve into the mathematics involved in extracting useful information from an image.

EVERY BIT COUNTS

Last month, I described an operation called threshold, in which each pixel in an image is compared with a threshold value and then replaced with one of two different values in order to make a binary image. In a similar fashion, you may want to analyze an image to see what information each bit plane represents. A bit plane is associated with each bit in a pixel. For example, what does the image look like if only the LSB of each pixel is used?

Photos 1býg show the six different bit planes contained in the original image in Photo 1a. Each image is a binary image created using a specific bit in each pixel. Depending on the application, the information in a particular bit plane may be more useful or easier to process than the original image.

a)	b)	c)
d)	e)	f)
g)	Photos 1aýgýThe original image (a) is shown using six bits per pixel. býg)ýHere you can see the bit plane in each pixel for bit 0, bit 1, bit 2, bit 3, bit 4, and bit 5, respectively. (click to enlarge)

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