CSC111 Lab 7 2014

--D. Thiebaut (talk) 12:45, 10 March 2014 (EDT)

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Page under construction!

Skeleton Program

# JES Picture processing
# D. Thiebaut
# A demo of some of the functions available in JES for manipulating 
# the pixels of an image.


# the image we are playing with
image = None

# changeColor( image ).
# Changes the amount of red, green and blue that is in an image
def changeColor( image ):
  for x in range(0,getWidth(image)):
    for y in range(0,getHeight(image)):
        pixel = getPixel (image, x, y)
        red   = getRed(pixel)
        green = getGreen(pixel)
        blue  = getBlue(pixel)
  
        # the line below replaces the pixel with its original color.  Change
        # the amount of red, green and blue to see some change in the colors
        newColor = makeColor( red, green, blue )
        setColor( pixel, newColor )
  return image

# ==================================================================  
#                             MAIN PROGRAM
# ==================================================================  
file = pickAFile()
image = makePicture( file ) 
show( image )
  
#image = changeColor( image )
#repaint( image )

Problem 1: random processing

Write a function (use the skeleton program for a skeleton function with nested for-loops) that modifies the red, green and blue components of each pixel.

Problem 2: black and white

• Make your image black and white by storing the same value in the green, red, and blue component of a pixel. In a first step, pick the amount of red of the pixel and store that number in the 3 components.

• Next take the average amount of red, green and blue and store that value (store it in a variable called grey for example), in all three components.

• Better: initial the grey variable as follows:

  grey  = int( 0.3 * red +0.6 * green +0.11 * blue )

Problem 3

Copy paste this function that contains a call to repaint( image ) inside the for x in range(...) loop. See how the program "sweeps" through the image.

Modify the function so that the sweep goes from left to right.

Modify the function so that the sweep goes from top to bottom

Modify the function so that the sweep goes from bottom to top

Problem 4

Pick one of the functions you have written for the problems above and make a new copy of it under a different name.

Replace the nested for-loop with this loop:

  for x in range( getWidth( image ) ):
      for y in range( min( x, getHeight( image ) ):

Predict the way the image is going to be transformed by these nested for-loops.

Problem 5: Border

Write a new function called addBorder( image, borderWidth ) that will put a red border around the image.

Modify the program and ask the user to pick a color first, then pass this color to the function addBorder( image, borderWidth, color ) which will put a border all around the image.

Problem 6: B&W image with Colored Border

Make your program output a version of your colored image that will be black and white with a colored border around it.