- if `SLIDESHOW_RESOLUTION` is unset images will be requested in their original resolution.
- if `SLIDESHOW_PALETTE` is unset no color palettes will be requested.
- if `SLIDESHOW_SCRIPT_STAGE` is unset the script (if specified) will be executed **after** the background image has been set **and** the color palette file has been generated.
### stages:
-`pre_image`: executes the script **before** the background image will be set.
-`post_image`: executes the script **after** the background image has been set.
-`pre_palette`: executes the script **before** the color palette file will be generated.
-`post_palette`: executes the script **after** the color palette has been generated.