Re: [Plplot-devel] x20c.c

[Andrew R. <ar...@ge...>]

>My motivation here is to have a good-looking demo.  Obviously something is
>not correct about the current method of reading in lena.pgm since the other

I believe the problem is caused by the fact that the image uses all 256
greyscales, whereas the PNG driver is using CMAP1's 240 greyslots (the
other 16 being taken by CMAP0) and at present no translation is being made.
So basically everything is moved "down" by 16 indices, and the top 16 are
lost. That is an issue that will probably have to be resolved even with GD,
although gd quite possibly has in-built functions that would simplify the
task.

>Now the big question for Andrew: would you be willing to programme png input
>to x20c.c using libgd (version 2)?  I am willing to do this myself starting
>tomorrow using libgd version 2.0.1 that is on my Debian woody system, but it
>might take me a while and with your C skills it might be trivial for you to
>do. Even if you provide just the bare bones of the png reading programme, it
>would help me get a much quicker start.  Let me know what you decide.

I will have a loot at it tomorrow and see what is involved and get back to
you. 
- Andrew