These challenges involve processing pre-existing image files, by altering them in some way, gathering statistics, or other image processing tasks.

learn more… | top users | synonyms

59
votes
5answers
4k views

Recognise Stack Exchange Sites by Their Icon

After spending a while on Stack Exchange, I can recognise most sites in the Hot Network Questions by their little icon (which is also their favicon), but certainly not all of them. Let's write a ...
29
votes
4answers
2k views

Paint by Numbers

You're given a true colour image. Your task is to generate a version of this image, which looks like it was painted using paint-by-numbers (the children's activity, not nonograms). Along with the ...
23
votes
5answers
740 views

Create icy avatar images for the winter season

It's winter, and the time of year has come for it to start getting cold (and for strange colorful headcloths to start appearing... soon). Let's write some code to make avatar pictures and other ...
61
votes
9answers
5k views

Counting Grains of Rice

Consider these 10 images of various amounts of uncooked grains of white rice. THESE ARE ONLY THUMBNAILS. Click an image to view it at full size. A: B: C: D: E: F: G: H: I: J: Grain ...
56
votes
7answers
3k views

Square, Circle, Triangle, …Gear?

Using Algodoo and Paint I made these six 300×300 monochromatic images of four convenient shapes: This class of images has the following properties: They are always 300×300 pixels, ...
15
votes
5answers
647 views

Mondrian painting description language

This challenge consists in coding an interpreter for a Mondrian painting description language (MPDL). Language definition The language operates on a stack of rectangles. A rectangle is defined by ...
17
votes
3answers
1k views

Hungry Image Snake - Hole #3

Hole #1 Joe the snake is hungry. He eats pictures, one pixel at a time. He really likes bright pixels. The Challenge Program Joe to eat the most bright pixels he can find, given that he can only ...
22
votes
1answer
674 views

Paint a still life (or a moving one) - draw an image in the Game of Life

You are given as input a greyscale image. Your task is to find a static or looping pattern in Conway's Game of Life that resembles the input image as closely as possible. Your output can be either a ...
21
votes
1answer
756 views

Stitch a picture

NOTE: This question is currently in the SANDBOX. Please bear this in mind before adding new answers. I have a large collection of fine art. My toddler is learning to use scissors and glue; lately ...
5
votes
4answers
505 views

Find a thumbnail in a mosaic

After the last Ludum Dare (LD) game programming contest a friend of mine made a nice mosaic of all the LD game thumbnails: After searching for my own game I quickly gave up and decided to solve it ...
18
votes
3answers
811 views

Life can be colorful!

Each cell in a life-like cellular automaton only needs one bit to represent it since it can only be alive or dead. That means there are only two colors; pretty boring. Normal images have 24 bits per ...
42
votes
6answers
3k views

Redraw an image with just one closed curve

Inspired by vi.sualize.us Goal The input is a grayscale image and the output is a black and white image. The output image consists of just one closed curve (loop) that is not allowed to intersect ...
28
votes
3answers
1k views

Reproduce an image using lines

Write a program that takes in a true-color RGB image I, the maximum number of lines to draw L, and the minimum m and maximum M length of each line. Output an image O that looks as much as possible ...
46
votes
8answers
4k views

Draw random black-and-white forest

Your task is to write program which will draw 800x600 black-and-white image with something resembling a forest. Like this (it is dithered photo): Rules You are disallowed to use any existing ...
1
vote
10answers
1k views

Crop an image to a square

In this challenge, you will take an input image and crop it to make a square, leaving only the central part of the input image. The answers must work with landscape, portrait, or square input images. ...
65
votes
25answers
10k views

Rearrange pixels in image so it can't be recognized and then get it back

Create a program which can rearrange pixels in image so it can't be recognized. However your program should able to convert it back to original image. You can write two functions - for encoding and ...
22
votes
5answers
2k views

Draw an Image with a Snake

Imagine a continuous 2-dimensional path that can only turn left, right, or go straight, cannot intersect itself, and must fill a rectangular grid such as the grid of pixels in an image. We'll call ...
25
votes
6answers
2k views

Photomosaics or: How Many Programmers Does it Take to Replace a Light Bulb?

I've compiled a mosaic of 2025 headshots from the avatars of the top Stack Overflow users. (Click the image to view it full-size.) Your task is to write an algorithm that will create an accurate ...
286
votes
35answers
50k views

American Gothic in the palette of Mona Lisa: Rearrange the pixels

You are given two true color images, the Source and the Palette. They do not necessarily have the same dimensions but it is guaranteed that their areas are the same, i.e. they have the same number of ...
12
votes
9answers
1k views

Dither a Grayscale Image

Dither a grayscale image into pure black and white with your own algorithm. Guidelines: You must come up with your own new algorithm. You cannot use pre-existing algorithms (ex. Floyd-Steinburg) but ...
18
votes
3answers
1k views

Miniature Faking

As any amateur photographer can tell you, extreme post-processing is always good. One such technique is called "miniature-faking". The object is to make an image look like a photograph of a ...
21
votes
3answers
1k views

Hiding information in Cats

You are a secret agent trying to communicate with your fatherland. Of course the information needs to be hidden so no one eaves drops your message. What would be better suited than a cat? Everyone ...
25
votes
17answers
3k views

Output an image of your source code (not-quite-a-Quine)

Code golf: Print an image of the source code. Requirements Must output the image of the source code itself, not a version stored elsewhere and retrieved at run time. Code must be legible enough ...
11
votes
4answers
498 views

Recognize ASCII art numbers

Challenge Recognize ASCII art numbers. To make things interesting, three random points in the image might be flipped. For example: ***** * ** ** ** ** ** Input A 7x7 ...
13
votes
3answers
756 views

Freehand red circles

Over on http://meta.stackoverflow.com, we have a few memes of our own. One of them is Freehand Red Circles. See this post: So, the challenge is, can you draw freehand red circles... with code? ...
7
votes
4answers
749 views

Produce the number 2014 from an image

In the 2014 challenge, Michael Stern suggests using OCR to parse to 2014. I'd like to take this challenge in a different direction. Using built-in OCR from the language/standard library of your ...
52
votes
9answers
4k views

Encode Images into Tweets (Extreme Image Compression Edition)

Based on the very successful Twitter image encoding challenge at Stack Overflow. If an image is worth 1000 words, how much of an image can you fit in 114.97 bytes? I challenge you to come up with a ...
4
votes
4answers
422 views

Determine which of two ImageMagick .TXT images is more saturated

You have two images (64x64 pixels each): Your program must take the file names of each of them as command line arguments and determine which has more average saturation among their pixels. The ...