§ Assignment 2. Image Processing (1)
The section of Image Processing (1) was partly referred to a
document “Image Processing Fundamentals - Contents” available
from http://www.ph.tn.tudelft.nl/Courses/FIP/noframes/fipContents.html
also there is an excellent tutorials available from MATLAB’s help
on Image Processing Toolbox. The names of the subroutines
avaiable from the Image Processing Tool Box start with “im” as
im***.m To do image processing assignments, use images from the
USC-SIPI image database available from
http://sipi.usc.edu/database/
1. Apply histogram equalization to an image of your choice and
see if the cummulated histogram apploximately linearly
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increases with the intensity of the gray scaled image. The help
file of imhist indicates that HISTEQ Enhance contrast using
histogram equalization. HISTEQ enhances the contrast of
images by transforming the values in an intensity image, or the
values in the colormap of an indexed image, so that the
histogram of the output image approximately matches a
specified histogram. Study what histogram equalization would
do to color images and apply imhist to an indexed color
image. Explain what effects you exect from the histogram
equalization to color images. Does this give the same effect as
you can get Microsoft Office Picture Manager?
2. For an image of your choice, apply RGB to YUV conversion to
produce a luma image Y, and two chroma images U(Cb) and
V(Cr). Then, convert the YUV image back to its
corresponding RGB image. Then, calculate PSNR for the
reconstructed RGB image.
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3. Standard linear image filtering operations can be done in
MATLAB with a subroutine called imfilter in conjunction
with a function called fspecial that sets up a filter kernel to
one of the commonly used kinds. Possible values for TYPE are:
average averaging filter
disk circular averaging filter
gaussian Gaussian lowpass filter
laplacian filter approximating the 2-D Laplacian operator
log Laplacian of Gaussian filter
motion motion filter
prewitt Prewitt horizontal edge-emphasizing filter
sobel Sobel horizontal edge-emphasizing filter
unsharp unsharp contrast enhancement filter
Try all of the smoothing filters and edge enhancing filters.
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