string2png is a small, flexible utility to compile strings to PNG images files. It is intended to ease the creation of extremely low resolution graphical assets such as gradient and patterns. It may also be used for abstract data visualization, glitch art and basic steganography.

Installation

npm install -g string2png

Examples

Note: All images have been enlarged to ease viewing. Actual output is miniscule.

rgb

Simple 3-pixel png

string2png  ff0000 00ff00 0000ff -o example/rgb.png

checkerboard

Checkboard pattern

string2png --encoding hex2 --width 2 --channels v f00f -o example/checkerboard.png

glitch

This page as glitch.

string2png --input README.md --square --normalize 1 --encoding ascii --background red --channels hsv --output example/readme.png

See example/README.md for more examples.

Usage

Javascript

const string2png = require('string2png')

// Default options
const options = {
  encoding: 'hex',
  channels: 'rgb',
  width: 0,
  height: 0,
  background: 'rgba(0,0,0,1)'
}

// Write to a PNG file
string2png.output( 'ff0000 00ff00 0000ff', 'outputfile.png', options )
  .then( () => console.log('Wrote file') )

// Return PNG as buffer
let buffer = string2png.png( 'ff0000 00ff00 0000ff', options )

// Return PNG as data URI
let data = string2png.datauri( 'ff0000 00ff00 0000ff', options )  

// Get normalization parameters
let { data, measured } = await string2png( {
  input: 'yourdatafile.csv',
  encoding: 'float',
  normalize: 6,
  measure: true,
  channels: 'v',
})

Command line

By default, the utility string2png will output a data URI string to stdout. To output a file, use the --output or -o option. Any non-options on the command line will be appended to stdin and used as input data.

Make a single green pixel by piping stdin:

echo 00ff00 | string2png

Options

encoding

• hex default - Parse hexadecimal data like CSS colours. All non-hex input will be ignored. Example: ff0000
• hex2 - Parse CSS-style short hex data. Each hex digit will be a single value. Example: f00
• float - Search input data for all substrings that look like numbers. Any delimiter maybe be used. Example: 0.5 0 0 - CSS maroon
• percent - Like float, except divide by 100. Example: 0 100% 100 - CSS Aqua
• decimal - Like float, except divide by 255. Example: 220,20,60 - CSS Crimson
• ascii - Interpret data as 8 bit binary.

channels

A string or array list of colour channels to be interpreted from input, in the order they are to be parsed. The default is rgb. Supported channels are rgba and hsv. See examples for many different usages of the channels option.

Any unrecognized channel will be parsed and thrown out, allowing padding within data.

data

String containing data to be processed.

input

Load any number of files or urls, and append to data. URLs will be loaded with the request module.

width

The width, in pixels, of the output file. If width is not specified, it will default to the length of parsed colour data, giving a height of 1. If width is specified, the length of data will be rounded up to the nearest divisor of width by padding with background to ensure a rectangular output.

height

If height is specified, the output will be cropped or padded.

square

If specified, width and height will be set to the square root of data length, providing a roughly square output.

background

The default value to use for pixel output. Any CSS string may be used. This colour value can be altered by input data on a channel-by-channel basis. See example alter-red

raw

Dump data to stdout as binary, rather than datauri. Does not affect output.

normalize

Specify number of columns to normalize. Each column will be normalized separately, mapping to a 0-1 range. Normalization is applied before channels. Best used with float encoding.

measure

Output normalization parameters to a JSON file from command line.