web scrubber


Sometimes a little dithering in the browser can improve the quality of your image. But how do you control which areas get dithered and which areas don't?

Try scrubbing your image. Colors that are nearly Web Safe are shifted so that they use one of the 216 colors. Colors that aren't close to being Web Safe are left alone to dither when displayed in the browser.

There are several implementations of this basic algorithm. They all require many steps to produce the final results. This filter does all these steps at once. It works well in conjunction with Browser Preview.

Here is the interface:

 








































colors

The Colors pop-up lets you select the number of colors for the image. The smaller the numbers, the smaller the file. But don't get too carried away; the quality will suffer.

The Wide checkbox allows you to select the colors using two different methods. When it is selected, the colors are chosen by the intensity at which your eye sees them. Otherwise, the numerical values of the colors are used.


red, green and blue

The sliders for Red, Green and Blue adjust the amount of scrubbing (in other versions of this algorithm it is called "grit"). The higher the number, the closer the image will be to a pure Web Safe palette. If the number is low, then there will be more dithering of the image.

The color ramps are adjusted to show how the current settings affect the range of colors.

When the Lock checkbox is set, the controls are adjusted simultaneously.


brightness & contrast

These controls work just as you'd expect them to. You can use them to improve the overall quality of the graphic.


thanks

Thanks to Todd Fahrner for developing this algorithm. Philip Gwyn is responsible for the original Web Scrub filter (produced with Filter Factory). Thanks to both of them for sharing this trick with others.

For Todd and Philip's contact information, please visit the Web Scrubber page at www.furbo-filters.com