digital image processing, phyton

Project 6 - Color Theory

In this project, you will implement the following:

1. Extract the YUV bands of an image

2. Decimate the Y band and show its effect on the quality of the RGB image

3. Decimate the U band and show its effect on the quality of the RGB image

4. Decimate the V band and show its effect on the quality of the RGB image

# import necessary packages # reading/writing image files

from skimage import io

from skimage import color

# displaying images and plots

import matplotlib.pyplot as plt

# array operations

import numpy as np

# mathematical calculations

import math

import cmath

# DFT calculations

from scipy import fftpack as ft

# histogram calculation

from skimage import exposure

# signal processing operations

from scipy import signal

from scipy.linalg import circulant

# display an image in original size

def my_display_actual_size(img, str_caption): height = img.shape[0]

width = img.shape[1] ndim = img.ndim

isColor = True

if ndim == 1: isColor=False elif ndim != 3: assert False

# determine a figure size big enough to accomodate an axis of xpixels by ypixels # as well as the ticklabels, etc.

margin = 0.05

dpi = 80

figsize = (1.0+margin)*height/dpi, (1.0+margin)*width/dpi

# define the figure

fig = plt.figure(figsize=figsize, dpi=dpi)

# make the axis the right size

ax = fig.add_axes([margin, margin, 1 - 2*margin, 1 - 2*margin])

# display the image

if isColor:

ax.imshow(img, interpolation='none')

else:

ax.imshow(img, cmap='gray', vmin=0, vmax=255, interpolation='none') plt.title(str_caption)

plt.show()

return

# end of function

# STEP 0 Pick an image

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# set image folder

image_folder = r''

# read input image

image_file = r'/peppers.png' image_path = image_folder + image_file imgRGB = io.imread(image_path)

# display image

my_display_actual_size(imgRGB,'Input Image')

# STEP 1 Transform the image into YUV color space #

# Extract the YUV bands of the image using "my_RGB2YUV()" function #

# ADD YOUR CODE BELOW

# STEP 2.a Demonstrate the effect of the Y band on image resolution #

# Decimate the Y band by a factor of 4 in horizontal and vertical directions #

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# ADD YOUR CODE BELOW

#

# Interpolate the decimated Y band back to its original size #

# ADD YOUR CODE BELOW

#

# Convert from YUV back to RGB (use the processed Y band) #

# ADD YOUR CODE BELOW

#

# Calculate and print the RMSE between the above image and the original image #

# ADD YOUR CODE BELOW

# STEP 2.b Demonstrate the effect of the U band on image resolution #

# Decimate the U band by a factor of 4 in horizontal and vertical directions #

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# ADD YOUR CODE BELOW

#

# Interpolate the decimated U band back to its original size #

# ADD YOUR CODE BELOW

#

# Convert from YUV back to RGB (use the processed U band) #

# ADD YOUR CODE BELOW

#

# Calculate and print the RMSE between the above image and the original image #

# ADD YOUR CODE BELOW

# STEP 2.c Demonstrate the effect of the V band on image resolution #

# Decimate the V band by a factor of 4 in horizontal and vertical directions #

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# ADD YOUR CODE BELOW

#

# Interpolate the decimated V band back to its original size #

# ADD YOUR CODE BELOW

#

# Convert from YUV back to RGB (use the processed V band) #

# ADD YOUR CODE BELOW

#

# Calculate and print the RMSE between the above image and the original image #

# ADD YOUR CODE BELOW

# STEP 3 Display the images obtained in STEP 2 above together with the original image #

# Display the original RGB image and the three RGB images obtained above in a 2x2 grid: # [Original RGB] [Y decimated RGB]

# [U decimated RGB] [V decimated RGB] #

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# ADD YOUR CODE BELOW

STEP 4 Comments on the results ADD YOUR COMMENTS HERE

Compare the three RGB images obtained in STEP 2 to the original RGB image in terms of (a) visual quality and (b) RMSE value and explain why decimation of different YUV bands have different effects on the RGB image quality.

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