Indie game storeFree gamesFun gamesHorror games
Game developmentAssetsComics

I thought it might be useful to provide some details on how 16-color backgrounds can be imported as of Decker v1.12, which includes fixes and tweaks for a few minor but annoying stumbling blocks. There are many tools available for dithering images, and many algorithms and settings to choose from. In these examples I'll be using the command-line image manipulation utility imagemagick, because it is free, available on all popular operating systems, and easily automated.

Decker has an internal 16-color palette based on the 16-color Macintosh palette, with convenient named constants for each color in the global "colors" dictionary:

We'll need a reference image describing this palette in order to remap a full-color image. The easiest way to obtain one is to ask in Decker's listener. Execute this and save the result as "lut.gif":

each c k i in colors r[i,0]:c end

Then, choose an image of something beautiful, like a chicken:

Next we'll use the imagemagick "convert" utility from our operating system's command line. If we just "remap" our input image, we get a posterized result:

$convert gally.jpg -resize 512x342 -remap lut.gif output1.gif

A Floyd-Steinberg dither is much smoother:

$convert gally.jpg -resize 512x342 -dither FloydSteinberg -remap lut.gif output2.gif

An ordered dither is much grainier, but might be desirable if you specifically want to evoke a 90s aesthetic. I found experimentally that this image needs some contrast tweaks to avoid a washed-out result:

$convert gally.jpg -brightness-contrast -10 -resize 512x342 -ordered-dither o4x4 -remap lut.gif output3.gif

And of course there are many, many more parameters available to tweak.

Now that we have a dithered image, we can import it into Decker and splat it onto the current card background with the listener:


If our converted image doesn't exactly match the size of a card, we can go a step further by filling the card with black and then centering our image, for a nice letterbox effect:

i:read["image"][() 1]
card.image.paste[i .5*card.size-i.size]

Now let's say we have a whole directory of wonderful chicken pictures (and who doesn't, really?) that we want to turn into a series of cards. We could use the above steps to prepare each one individually, but we could also use Lilt, the command-line counterpart of Decker, to automate the whole process, including invoking imagemagick:

What's particularly nice about this approach is that it's repeatable: at any time, you can re-run the script to regenerate backgrounds and add cards as necessary, while leaving any widgets, scripts, or other deck customizations intact.

Hope that helps!


A brief followup: v1.20 slightly modified the behavior of "range", requiring an adjustment to the above script:

When looking up a card by index, instead of[(range[index]]

The "range" operator can now be used more directly:


thanks for the amendment 


Small notes for anyone being lazy, (Like me)

If you fit one of the dimensions it will center fine, so if you have a whole bunch of taller than wide photos, just scale to width and let the code center it.

You can also reduce the colors any way you want, and it will still work fine. 

i:read["image"][() 1] card.image.paste[i .5*card.size-i.size]

Try importing random photos without doing any color reduction for neat effects

How can you save something after using the Listener ? Like, I paste the code into the listener ? And then, how can I save it into "lut.gif" ? Thanks a lot !

(2 edits)

The "write[]" function prompts the user to save a file. If you call write[] with an image interface, for example, it will prompt the user to save that image as a .GIF image file.

After you paste code into the listener, don't forget that you need to press shift+enter to evaluate it! The reference manual section for the listener can be found here:


I see, thanks !