Where can I do it?
At the Toolbox (bottom of the Liquipedia sidebar to the left), there is an option to upload a file. Simply click on it.
What format to use for what
- JPEG is a lossy format. It works well for photos, but has problems with images which include larger monochromatic areas. If you use jpeg please always use an uncompressed image so that it can be modified if required without increasing the quality loss.
- PNG is a lossless format. It works well for monocromatic areas, images with few colors and exactly repeating parts of the image. Thus it is optimal for the flowcharts we use. It is also superior for screenshots of SC1.
Details on choosing a format can be found on r1ch's homepage.
How to create a good png
- Get the raw image. Converting a image from jpeg to png does not work well, so use the original screenshot
- If the image has few colors reduce the color depth to 256. This can be done losslessly for starcraft screenshots since SC only has 256 colors. If you open a pcx which SC uses for screenshots it already has 256 colors, so you can skip this step.
- Save it as png.
A nice program for doing that is irfanview with plugins(download on the same page). Save using the png out plugin on using unlimited passes and colortype+filter on auto usually produces the smallest images. A typical SC screenshot is ~100kB as a 256 color png, and about 250kB as decent quality jpg.