# *********************************************************************************#
# ImageReader Class #
# This class contains the methods to read the image data #
# Author: Marina Gonzalez #
# Author: Eduardo Rodes Pastor #
# *********************************************************************************#
from PIL import Image
def get_image_data(filename):
"""
This gets the width and height of an image (in pixels) and the total number of pixels of it.
:param filename: image file
:return: width, height, number of pixels
"""
im = Image.open(filename)
width = im.size[0]
height = im.size[1]
npix = im.size[0] * im.size[1]
return width, height, npix
def get_rgb(filename, npix):
"""
This gets the RGB values from a given file and saves them in three lists from a given file.
:param filename: image file
:param npix: number of pixels
:return: r, g, b
"""
# Getting image pixels RGB values
im = Image.open(filename)
rgb_im = im.convert('RGB')
# Creating three lists of npix items
r = [-1] * npix
g = [-1] * npix
b = [-1] * npix
for y in range(0, im.size[1]):
for x in range(0, im.size[0]):
# We get the RGB value in each pixel and save each component in an array
rpix, gpix, bpix = rgb_im.getpixel((x, y))
r[im.size[0] * y + x] = rpix
g[im.size[0] * y + x] = gpix
b[im.size[0] * y + x] = bpix
return r, g, b
def get_yuv(filename):
"""
This gets the YCbCr values from a given file and saves them in three lists from a given file.
:param filename: image file
:return: y, u, v
"""
# Getting image pixels RGB values
im = Image.open(filename)
im = im.convert('YCbCr')
y = []
u = []
v = []
for pix in list(im.getdata()):
y.append(pix[0])
u.append(pix[1])
v.append(pix[2])
return y, u, v
def rgb_to_yuv(r, g, b): # in (0,255) range
"""
This converts three lists (red, blue, green) in their equivalent YUV lists.
:param r:
:param g:
:param b:
:return: Y, Cb, Cr
"""
# All of these lists have the same length
y = [0] * len(r)
cb = [0] * len(r)
cr = [0] * len(r)
# This is just the formula to get YUV from RGB.
for i in range(0, len(r)):
y[i] = int(0.299 * r[i] + 0.587 * g[i] + 0.114 * b[i])
cb[i] = int(128 - 0.168736 * r[i] - 0.331364 * g[i] + 0.5 * b[i])
cr[i] = int(128 + 0.5 * r[i] - 0.418688 * g[i] - 0.081312 * b[i])
return y, cb, cr
