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Reducing Map File Sizes

PostPosted: 20 Oct 2013, 19:06
by Morg
Note from Pedros - Morg has produced several maps for me lately. All are of unusual quality, particularly clarity. Listen to what he has to say!

While producing variant maps can be fun and successful maps can be satisfying to run, there is a challenge of keeping the map under the designated file size limit of 60kb. So consulting with another prolific map designer Attitudes, we’ve come up with a handy set of tips to reduce that file size so that your map fits within the limits and can be run without anyone chastising you for the file size.

1. Maps should always be saved as a .gif before uploading them to the site. This file type has been seen as ideal and keeps the same map size smaller in terms of kb than other file types.

2. Maps should whenever possible have a canvas size of no more than 900 pixels by 600 pixels. This is a good standard. Most maps can be made even smaller than that, but this is a solid size. Large enough to fill the screen, yet still small enough to keep the whole map visible on a standard size screen.

3. Use fewer colors. Clearly you want each country to have its own color and you want to have enough color to add depth, but you need to use solid colors. Oftentimes when a map is reduced in size, many of the pixels will change their colors in slight degrees leaving pockets of individual pixels in shades other than the main color of the province. File sizes will be dramatically reduced by eliminating all of these small isolated pixels of slightly different shades. I have seen maps go from over 100kb down to 30kb just by eliminating these small differently shaded pixels.

A great tool for getting rid of these is to use the fill tool and use the global flood mode. This will change all of the pixels of the same shade on the map to the color selected.

4. Along these lines, whenever you use the brush, erase, or even the text tools, always, always have antialiasing disabled. Antialiasing, when enabled, blends the color you’re using with the colors surrounding it creating hundreds of slightly differently shaded pixels each time you use it. This undoes all of the work you put into doing tip number 3.

These tools have their own toolbar. On the far right of this tool bar there is a curved line with 3 dots on it, click it and make the line zigzag and you will have saved yourself a ton of space. A complete list of tools that have an antialiasing option are paint; brush, erase, stamp, text, line, rectangle, rounded rectangle, ellipse, and freeform shape. Anytime you have the option always disable antialiasing. Attitudes and I cannot stress this enough.

You can make Antialiasing Disabled the default setting now. Instructions on how to do so are outlined here. This should save you a lot of work or at least effort.

5. Allow space for the units. Ideally you’ll want to have the map down to about 50kb so that when the units are on the board you can still stay under the file size limit. The units should also be simple. They are usually 2 colors, a black outline and the country color. Overcomplicated units or units with too many colors in them will ruin all the hard work you put into getting the map down to proper size.


While there are plenty of other tricks and tips Attitudes and I have, so does every mapmaker, but these tips will get your map down to file size and help us all save space. If you have any questions, feel free to PM either one of us.

Re: Reducing Map File Sizes

PostPosted: 09 Apr 2014, 06:23
by JacobiGalt
Is there a particular program that lets you do all this? I've just been using paint?

Re: Reducing Map File Sizes

PostPosted: 09 Apr 2014, 06:46
by Morg
JacobiGalt wrote:Is there a particular program that lets you do all this? I've just been using paint?

Use "Paint.NET" it is free to download and is pretty much the unofficially official program for maps in the DVFG community.