How do ASCII art image conversion algorithms work? [closed]

by

The big-picture-level concept is simple:

  1. Each printable character can be assigned an approximate gray-scale value; the “at” sign @ obviously is visually darker than the “plus” sign +, for example. The effect will vary, depending on the font and spacing actually used.

  2. Based on the proportions of the chosen font, group the input image into rectangular pixel blocks with constant width and height (e.g. a rectangle 4 pixels wide and 5 pixels high). Each such block will become one character in the output. (Using the pixel blocks just mentioned, a 240w-x-320h image would become 64 lines of 60 characters.)

  3. Compute the average gray-scale value of each pixel block.

  4. For each pixel block, select a character whose gray-scale value (from step 1) is a good approximation of the pixel block average (from step 3).

That’s the simplest form of the exercise. A more sophisticated version will also take the actual shapes of the characters into account when breaking ties among candidates for a pixel block. For example, a “slash” (/) would be a better choice than a “backward slash” (\) for a pixel block that appears to have a bottom-left-to-upper-right contrast feature.

More Related Contents:

  1. The number prodigy : reverse sum of pattern
  2. Pseudocode – Largest to smallest integer [closed]
  3. How can I pair socks from a pile efficiently?
  4. RGB values of visible spectrum
  5. How do I calculate the area of a 2d polygon?
  6. Simple calculations for working with lat/lon and km distance?
  7. Finding a single number in a list [duplicate]
  8. Minimum number of swaps needed to change Array 1 to Array 2?
  9. Division without using ‘/’
  10. Precise subpixel line drawing algorithm (rasterization algorithm)
  11. Algorithm to find next greater permutation of a given string
  12. What’s a good algorithm to determine if an input is a perfect square? [duplicate]
  13. nᵗʰ ugly number
  14. Optimal algorithm for returning top k values from an array of length N
  15. Argument for O(1) average-case complexity of heap insertion
  16. How to partition an array of integers in a way that minimizes the maximum of the sum of each partition?
  17. How to rank a million images with a crowdsourced sort
  18. insert, delete, max in O(1)
  19. How Can I Best Guess the Encoding when the BOM (Byte Order Mark) is Missing?
  20. How does Dijkstra’s Algorithm and A-Star compare?
  21. Permute all unique enumerations of a vector in R
  22. Easiest algorithm of Voronoi diagram to implement? [closed]
  23. “Rounding” colour values to the nearest of a small set of colours
  24. What algorithm can calculate the power set of a given set?
  25. Color gradient algorithm
  26. Calculating frames per second in a game
  27. Which is faster, Hash lookup or Binary search?
  28. Group n points in k clusters of equal size [duplicate]
  29. How to generate a power set of a given set?
  30. Complete graph with only two possible costs. What’s the shortest path’s cost from 0 to N – 1

Leave a Comment