ASCII Art Image Converter

How the conversion works

Every character in a monospace font has a visual weight — how much ink it puts on the page. A full stop is almost nothing, an @ is nearly solid. Line them up from lightest to heaviest and you have a greyscale ramp made of letters.

The image is then shrunk to a grid the size of the output — 80 columns wide, say — so each cell holds the average brightness of that part of the picture. Match each cell's brightness to the nearest character in the ramp, print the rows, and the picture reassembles itself out of text.

Why the grid is squashed vertically

A monospace character is roughly twice as tall as it is wide. If the sample grid matched the image's true proportions, the printed result would come out stretched to double height. The fix is to sample about half as many rows as the aspect ratio suggests, which is what this tool does — and it is the single most common thing people get wrong when writing their own converter.

Choosing a character set

The block characters are Unicode rather than ASCII, so they need a font that includes them — nearly all modern ones do, but a very old terminal may show boxes instead.

Where to paste it

• A terminal — the native home for this. Works perfectly.
• A code block — on GitHub, Slack, Discord or Reddit, wrap it in triple backticks so the monospace font is preserved.
• A plain text file — Notepad, TextEdit in plain text mode, or any code editor.
• Email — only if you can force a monospace font. Most clients will reflow it into nonsense.
• Social media — generally reflows and destroys it. Use the PNG download instead.

Getting a good result

• Crop tightly to one subject. Detail spent on background is wasted at this resolution.
• Raise the contrast. ASCII has very few tonal steps and contrast is what separates them.
• Try the invert switch if the output is going on a dark terminal — the ramp needs to run the other way.
• Silhouettes and logos convert far better than busy photographs.
• If it looks like noise, halve the width. Fewer, better-chosen characters beat more mushy ones.