What is the fastest way to draw an image from discrete pixel values in Python?

Question

I wish to draw an image based on computed pixel values, as a means to visualize some data. Essentially, I wish to take a 2-dimensional matrix of color triplets and render it

Answer 1

Requirements

For this example, install Numpy and Pillow.

Example

The goal is to first represent the image you want to create as an array arrays of sets of 3 (RGB) numbers - use Numpy's array(), for performance and simplicity:

import numpy

data = numpy.zeros((1024, 1024, 3), dtype=numpy.uint8)

Now, set the middle 3 pixels' RGB values to red, green, and blue:

data[512, 511] = [255, 0, 0]
data[512, 512] = [0, 255, 0]
data[512, 513] = [0, 0, 255]

Then, use Pillow's Image.fromarray() to generate an Image from the array:

from PIL import Image

image = Image.fromarray(data)

Now, "show" the image (on OS X, this will open it as a temp-file in Preview):

image.show()

Note

This answer was inspired by BADCODE's answer, which was too out of date to use and too different to simply update without completely rewriting.