Re: [gentoo-user] Cmdline image resizer understanding gamma ?

[Sebastian Pipping]

On 05/06/2011 12:05 AM, Paul Hartman wrote:
> Doesn't Netpbm satisfy your criteria? It's the very first program on
> the list of "good" software in that web page.

I have a had a closer look at netpbm's pamscale now.


pamscale doesn't support PNG input out of the box:

  "pamscale: bad magic number 0x8950 - not a PAM, PPM, PGM, or PBM file"

So to let pamscale operate on my PNG it seems I would need to run this

  # pngtopam in.png > in.pam
  # pamscale [..] in.pam > out.pam
  # pamtopnm out.pam > out.pnm
  # pnmtopng out.pnm > out.png

I haven't checked yet if that preserves transparency.

While there is a tool pamrgbatopng shipped with netpbm it didn't like my
out.pam produced above:

  "pamrgbatopng: PAM must have depth at least 4 (red, green, blue,
   alpha).  This one has depth 3"

Interestingly netpbm tools point to a respective man page when run with
--help, which points to a man-like website with the real content.  So it
seems without internet the tool is effectively unusable.  Great.

I'm also not sure if I really want to add 300 binary files from a single
package:

  # equery f media-libs/netpbm | grep '^/usr/bin' | wc -l
  331

Best,



Sebastian