[vtk-developers] zlib

[Sebastien BARRE]

At 01/11/00 12:15, Michael Halle wrote:

>I know that there's been a long-standing philosophy that vtk is
>easiest maintained when it is standalone, not dependent on outside
>libraries except when essential.  I would like to discuss the
>possibility of making an exception and adding zlib to a future vtk
>release.

I do agree with you, zlib is a good candidate, I've been using it myself as 
part of a freeware I've written, and it is very easy to use. The static lib 
is small.

>* Many of the data and image files in visualization are enormous, yet
>   sparse. A standard compression would be extremely helpful, and improve
>   the speed of loading over network-mounted disks or the net.

As the vtkdata and vtkbaseline are growing and growing, we could shrink 
them easily.

>* with zlib, it's possible to read and write PNG files, which support
>   up-to-16 bit grayscale images, 48 bit truecolor images, color-palette
>   images, and alpha transparency.  PNG is a very simple format (simpler
>   than TIFF), so you don't really need libpng, but you need to have
>   zip compression.

Indeed libpng is *very* small and portable too, both projects have the same 
philosophy.
But as we already have a TIFF writer, we might be able to use the zlib 
compression scheme in TIFF.

>* it's very portable (compiles across more platforms than vtk).

I've tested Solaris, Linux, Windows (Borland and VCC). No problem at all.