[Ohrrpgce] better palette options

[David Gowers (kampu)]

On Fri, Oct 8, 2010 at 11:42 PM, David Gowers (kampu) <00ai99 at gmail.com> wrote:
> http://bpaste.net/show/10001/
> ^^^^^
> The format proposition
>

Note that I intentionally made it as unrestricted as possible.
Imposing additional constraints could allow the removal of certain
tuple types and runtime data fields. Whether additional constraints
are appropriate is a matter for discussion.

Comments on PNG:
* I saw your suggestion, Mike, and I thought : though it isn't the
only option, it has a lot going for it.

* Note we may want to rewrite imported images even if they are in PNG
already: Some programs (notably Photoshop) are pretty bad at
compressing PNG relative to libpng.

* I opted to include a simple source-tracking tEXT chunk
  to aid import <-> export cycles

* using PNG (and implicitly assuming 256-color sprite data) has the
side effect that we can play nicer with eg Grafx2, which always writes
a '256-color' image even though only the first 16 colors are used.

On another topic:
* my proposition does not include backgrounds or tilesets.
  I believe backgrounds can fit into the scheme in a natural way.
  I'm not sure what to do with tilesets as I understood that some
other upgrade relating to them is incipient, but not sure exactly
what.
* nor does my proposition address partial recoloring. With 256 color
sprites, it would be far easier to standardize on recoloring, so, for
example, you could fill a 256-color palette via sets of 16, and just
swap in/out sets of 16 to recolor things easily.
* related to the above: color cycling, while not *important*, might be
something we want to consider (eg for showing elemental effects on a
character)