Location Based Conditions

Section 26.5 Location Based Conditions

We can also use the x and y coordinates of pixels to make decisions about what pixels to process. This program changes pixels to black only if their x coordinate is less than 20 or over 180.

Checkpoint 26.5.1.

Currently, this program changes the 20 leftmost and rightmost pixels to black. Modify it to turn the 40 left and rightmost pixels to black. (Hint: The image is 200 pixels wide.)

from image import *

img = Image("cat.jpg")
win = ImageWin(img.getWidth(),img.getHeight())
img.draw(win)
img.setDelay(1, 400)   #SPEEDS UP THE DRAWING

pixels = img.getPixels();
for p in pixels:

# GET PIXEL DATA
    x = p.getX()
    y = p.getY()

# TEST THE LOCATION
    if x < 20 or x > 180:

#MAKE THE COLOR BLACK
        p.setRed(0)
        p.setBlue(0)
        p.setGreen(0)

# CHANGE THE PIXEL
        img.updatePixel(p)
====
from unittest.gui import TestCaseGui

#account for weirdness with datafile color values
#return b if a is close to it, otherwise return a
def nudge(a, b):
    if abs(a.getBlue() - b.getBlue()) < 3 and abs(a.getRed() - b.getRed()) < 3 and abs(a.getGreen() - b.getGreen()) < 3:
        return b
    return a

class myTests(TestCaseGui): 
    def testOne(self): 
        p1 = img.getPixel(38, 10)
        p2 = img.getPixel(177, 10)
        p3 = img.getPixel(55, 10)
        
        targetPixel = Pixel(109,161,7)

p3 = nudge(p3, targetPixel)
        
        self.assertEqual(str(p1),"[0,0,0]", "Test if 40 pixels on left are black")
        self.assertEqual(str(p2), "[0,0,0]", "Test if 40 pixels on right are black")
        self.assertEqual(str(p3), "[109,161,7]", "Test that pixels in the middle are unmodified")

myTests().main()

You have attempted of activities on this page.