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LVZ/LVL Questions - converting 24 bit - 256 color tileset

AcidBomber - Tue Jul 11, 2006 12:22 am
Post subject: converting 24 bit - 256 color tileset

Anyone know how?

I tried it with Paint but the colours got distorted.

Thanksss

Purge - Tue Jul 11, 2006 12:40 am
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That's the only way... Save As -> 256 Color image.

SuSE - Tue Jul 11, 2006 1:34 am
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In decent graphic editors, you should be able to dither in various ways when you convert to indexed.

Assassin2684 - Tue Jul 11, 2006 9:12 am
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Try to get The GIMP or Photoshop.

AcidBomber - Tue Jul 11, 2006 4:01 pm
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actually i use Photoshop Element and I cant seem to find the converting to 256 function... anyone use the same version and can help?

Thanks!

Purge - Tue Jul 11, 2006 4:30 pm
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When you convert something from 24-bit to 256 colors, you will obviously lose some detail.

Why are you going to other programs to do the same thing?

Smong - Tue Jul 11, 2006 5:35 pm
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Because MS Paint does a poor job of converting it.

AcidBomber - Tue Jul 11, 2006 11:15 pm
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alrighty! i got it! thanks

Purge - Tue Jul 11, 2006 11:35 pm
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Smong wrote:

Because MS Paint does a poor job of converting it.

So do other programs make a better 256 color version?

Muskrat - Wed Jul 12, 2006 1:08 am
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Scroll back up and read Suse's post.

Purge - Wed Jul 12, 2006 1:10 am
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I don't understand such grammar.

Solo Ace - Wed Jul 12, 2006 2:50 am
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It's all on Wikipedia:

Wikipedia:Color_depth wrote:

With relatively low color depth, the stored value is typically an index into a color map or palette. The colors available in the palette itself may be fixed by the hardware or modifiable. Modifiable palettes are sometimes referred to as pseudocolor palettes.
...
8-bit color (28 = 256 colors) VGA at low resolution, Super VGA, AGA

Wikipedia:Color_depth wrote:

24-bit Truecolor uses 8 bits to represent red, 8 bits to represent blue, and 8 bits to represent green. 28 = 256 levels of each of these three colors can therefore be combined to give a total of 16,777,216 mixed colors (256 x 256 x 256). Twenty-four-bit color is referred to as "millions of colors" on Macintosh systems.

What the conversion from 24-bit images to 8-bit images means is that there's less space to store color data.
This means the image being converted has to be dithered, because not all colors can be stored in the 8-bit image.

Wikipedia:Dither wrote:

Another useful application of dithering is for situations in which the graphic file format is the limiting factor. In particular, the commonly-used GIF format is restricted to the use of 256 or fewer colors. Images in other file formats, such as PNG, may also have such a restriction imposed on them for the sake of a reduction in file size. Images such as these have a fixed color palette defining all the colors that the image may use. For such situations, graphical editing software may be responsible for dithering images prior to saving them in such restrictive formats.

Wikipedia:Dither wrote:

Dithering is a technique used in computer graphics to create the illusion of color depth in images with a limited color palette (color quantization). In a dithered image, colors not available in the palette are approximated by a diffusion of colored pixels from within the available palette. The human eye perceives the diffusion as a mixture of the colors within it (see color vision).

So, dither: Creating the illusion of new colors and shades by varying the pattern of dots.

There are several ways to dither an image, well, several algorithms...

Wikipedia:Dither wrote:

Dithering algorithms
There are several algorithms designed to perform dithering. One of the earliest, and still one of the most popular, is the Floyd-Steinberg dithering algorithm, developed in 1975. One of the strengths of this algorithm is that it minimizes visual artifacts through an error-diffusion process; the Floyd-Steinberg algorithm typically produces images that more closely represent the original than simpler dithering algorithms.

Other dithering methods include:

Average dithering: one of the simplest dithering techniques, based on selecting an average tone and choosing pixel colors based on how close they are to the average
Ordered dithering: produces a cross-hatch dithering pattern similar to the halftones used by print newspapers
Random dithering: introduces a random element to each pixel, resulting in a staticky image
Albie dithering: a method similar to Floyd-Steinberg, but optimized for display on interlaced monitors

You should be able to pick a dither algorithm based on what kind of result you want.
This is what Suse means. I don't know what MS Paint uses to dither images, but, well, according to Smong the algorithm it uses sucks.

Purge - Wed Jul 12, 2006 3:00 am
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...Thanks.