ColorRun

ColorRun cycles through color gradients that sweep across the applet area as rising scanlines. On the Amiga and Atari ST this kind of effect could be achieved without touching pixel data at all — by reprogramming the color palette registers via copper or HBL (horizontal blank) interrupts on each scanline, the hardware would display different colors per line from a single flat-colored framebuffer.

This Java applet recreates that classic raster bar look in software: a thin horizontal strip is cropped from the source image at a progressively increasing Y offset and painted onto the canvas, building up the picture scanline by scanline before looping back to the start. Just point the logo parameter at any GIF or JPG and the effect does the rest.

Note: This effect was originally a Java applet (1996). It has been transpiled to plain JavaScript / Canvas in 2026. The minified script is colorrun.min.js. Configuration is passed via a global COLORRUN_CFG object before the script tag.

Features

Raster-bar style scanline sweep over any logo image
Works with GIF and JPG images
Double-buffered rendering via hidden backbuffer canvas
Continuous looping animation
2×2 pixel zoom via CSS scaling (browser upscale, pixelated rendering)

Parameters (COLORRUN_CFG)

Name	Type	Description	Default	Required
`logo`	string	ID of hidden `<img>` element	"img1"	no

Code Example

<canvas id="game" width="288" height="132"></canvas>
<img id="img1" src="colorrun.gif" style="display:none">
<script src="colorrun.min.js"></script>

Original Applet Code

<applet archive="ColorRun.jar"
  code="ColorRun.class" width="144" height="66">
  <param name="logo" value="colorrun.gif">
</applet>

Version History

2026 — Transpiled from Java applet to JavaScript / Canvas
1.0 — Original Java applet release