CSCI 1101B Advanced Image Manipulation Techniques Mohammad T . - - PDF document

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CSCI 1101B

Advanced Image Manipulation Techniques

Mohammad T . Irfan 3/6/14

Red-eye reduction

 Write a function for red-eye reduction

 Parameters: picture file name (“jenny-red.jpg”)

and coordinates for the box

 Show and return the modified picture object

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Pseudocode

for every x coordinate within the box for every y coordinate within the box px = pixel at (x, y) if distance(red, px’s color) < 165 change px’s color to black/gray show the modified picture return the modified picture

Edge detection

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Tracking moving objects How to detect edges?

 What is an edge?

 There is an abrupt change of color

 Psueodocode

for each x coordinate for each y coordinate if the luminance of (x, y) pixel is very different from that of neighboring pixels, (x, y) is part of an edge

 In addition to the above, we want to create

a new picture that shows the edges

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Practice problems (class participation homework)

 Due on Tuesday, March 11  Blurring a picture (program 42)

 The filename parameter of the blur function must

be the file name with complete path. Only “flower1.jpg” for filename will not work. Write the following in command area to get the complete path:

 setMediaPath()  filename = getMediaPath(“flower1.jpg”)  blur(filename) #call the blur function with the

proper argument

 Did you understand why the ranges in for loops

started at 1 and ended 2 short of width/height?

class participation homework (cont.)

 Chromakey (Program 47)

 Here, the source and bg parameters are picture

• bjects. File names as arguments will not work.

You will need to create the picture objects from the command area first. You can then supply those picture objects to the chromakey function. Here’s an example for creating these picture objects (type the following in command area):

 file = getMediaPath(“blue-mark.jpg”) #assuming

setMediaPath() done previously

 source = makePicture(file)  file = getMediaPath(“moon-surface.jpg”)  bg = makePicture(file)  chromakey(source, bg) #call the chromakey function

with proper arguments