What

(2024-11, 2024-12, 2025-04)

"Plasm" gradient filling for 1-d images.

Command-line tool to generate image by given width, height and random seed.

How to use

Basic usage

$ lua Plasm_1d_ppm.lua

will use random seed and create/overwrite Plasm_1d.ppm image file. Also it will print something like

Config = {
  ColorFormat = 'Rgb',
  ImageHeight = 10,
  ImageWidth = 60,
  OutputFileName = 'Plasm_1d.ppm',
  RandomSeed = 1743896375,
}

Arguments

All values from Config except OutputFileName can be passed as positional parameters. Sequence is

ImageWidth ImageHeight ColorFormat RandomSeed

For example to specify ImageWidth (900) and ImageHeight (150) call

$ lua Plasm_1d_ppm.lua 900 150

Third optional argument is ColorFormat. Rgb for RGB and Gs for grayscale. (Grayscale is more sexy to my taste as you can directly treat values as relief height.)

Fourth optional argument is RandomSeed (int64). With same random seed, image width and color format you will get same result. That's why we are printing config. You can store just several bytes to recreate image.

Advanced usage

Tweak Plasm_1d_ppm.lua!

Important things there are parameters for plasm generator: Scale and TransformDistance function.

How it works

Recursive divisions. Each time we'll set middle pixel as average of border pixels plus noise. Noise is the essence. Noise amplitude depends of current segment length. Typically, shorter segment means less noise potential.

Instead of spending words, I left code in LinearPlasmGenerator.

Wtf is .ppm format?!

Huh, Plain pixmap. It's opening fine by xViewer in Linux Mint. GIMP opens it fine too.

If you bother to install netpbm package you can convert .ppm to .png from command-line:

$ pnmtopng Plasm_1d.ppm > Plasm_1d.png

How it can be used

I'm using it to generate pattern for RGB LED stripe above by monitor. And then scroll it smoothly. See my RGB stripe console project.

I think more common usages is background for PowerPoint presentation, lol. Just add logo and text.

I even found images generated by similar method as "digital art" which one site tries to sell. That's even worse than PowerPoint presentations.

Requirements

• Lua 5.3

It does not use any OS-specific functions so may run even under Windows!

Bonus stuff

DisplayPpm - quick script to display .ppm in console while you're rolling plasm generation.

Example:

lua Plasm_1d_ppm.lua 160 15; lua DisplayPpm.lua

That's text terminal guys! (There are fancy ANSI codes extension to set colors in RGB.)

Sorry Windows users, I don't think it will work on your system.

See also

• RGB stripe console originally this code was born there
• My other repositories (Lua and Arduino C++)