Python Imaging Library/Editing Pixels

With PIL you can easily access and change the data stored in the pixels of an image. To get the pixel map, call load() on an image. The pixel data can then be retrieved by indexing the pixel map as an array.

pixelMap = img.load() #create the pixel map
pixel = pixelMap[0,0] #get the first pixel's value

When you change the pixel data, it is changed in the image it came from (since the pixel map is just a reference to the data rather than a copy).

Example

Resultant image

The following snippet shows how to change the pixel values in an image based on the index of the pixel:

from PIL import Image

# PIL accesses images in Cartesian co-ordinates, so it is Image[columns, rows]
img = Image.new( 'RGB', (250,250), "black") # create a new black image
pixels = img.load() # create the pixel map

for i in range(img.size[0]):    # for every col:
    for j in range(img.size[1]):    # For every row
        pixels[i,j] = (i, j, 100) # set the colour accordingly

img.show()