Image Standards - Site

These are the guidelines for making images for the site.

Emulated images

This covers screenshots, sprites, maps - anything built from emulated images.

PNG format

Always create images in PNG format, not GIF, unless there is a truly pressing need for GIF anmimation.

1:1 scale

One image pixel should correspond to one emulated pixel. Disable all scaling, stretching and filtering.

Full range palette

Where possible, image palettes should be "full range" - so black is #000000 and white is #ffffff. This often corresponds to a "bright" palette setting in the emulator.

Optimise the PNG

Our preferred optimiser is PNGOUT, using the /f0 parameter on images with many colours. You can use other optimisers in "lossless" mode if preferred. You can easily batch-convert all PNG files of a same directory using the command-line version of PNGOUT:

for %i in (*.png) do pngout "%i"

Or create a batch file (any filename ending with .bat or .cmd extension) with:

for %%i in (*.png) do pngout "%%i"

And run it from the directory you want to convert.

Another good optimiser is advpng in "insane" mode, but it does not offer the option to change the filter mode so it may be best to use it after PNGOUT.

Scanned images

JPEG format

Use JPEG in all cases, except for black-and-white text-based images where PNG may be more efficient.

Format options

Given an option of "baseline"/"standard"/"incremental" or "progressive", choose the one that yields the smaller image for the same quality.
Do not use any "disable color subsampling"/"4:4:4" option unless the "standard"/"4:2:0" option provides significantly poorer images.

Quality and resolution

Follow the guidelines for the section you are in.