IAT 455 Study Guide - Midterm Guide: Grayscale, Digital Video, Color Vision
16 Dec 2015
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Suppose you wish to create a wavy effect, as in the figure below. This effect comes from replacing the image x value by an x value offset by a small amount. Make the maximum shift in x equal to 16 pixels. Write an expression that would show this transformation. x = x +16 * sin (y *0. 02) Suppose we decide to quantize an 8-bit grayscale image down to just 2 bits of accuracy. Just take the first 2 bits in the greyscale value. 1100 0000 to 1111 1111 are mapped into 4 representative greyscale values. Therefore, it is acceptable perceptually to remove a good deal of color information. In analog, this is accomplished in broadcast tv by simply assigning a smaller frequency bandwidth to color than to black and white information. In digital, we decimate the color signal by subsampling (typically, averaging nearby pixels). The purpose is to have less information to transmit or store.
