Eero Ahonen <aer### [at] removethiszbxtnetinvalid> wrote:
> Possibly surprisingly that's handness of the web developer. PNG supports
> transparency, so there actually should be no real need to get the same
> background color as at the page.

  Transparency may not always be the answer. Sometimes you may want to
use color fadings which are not possible to achieve with the alpha channel.

> Fortunately for you JPG's are usually far more practical on the web,
> while they take up less space.

  A jpeg takes more space if the image is simple and uses just a few
colors. (Ok, you *can* make it take less space, but then the image will
look like crap.)

> I quickly checked the PNG specs and seems the specified way is to guess
> the gamma. I'm not sure if it's a good idea.

  IMO it's a bad idea. I understand why they specified it like that,
but I think it's still a mistake, and less problems would have arised
if they would have not.

> > Some programs follow this rule, others don't. 

> ...it's still specsed, so every program should follow the rule. The
> final colors would vary less.

  Even if all browsers followed the PNG recommendations to the letter,
you still couldn't be sure to get matching colors between the PNG and
other elements in the page. The browser would have to apply the same
gamma correction to the other elements in the page too (which, if it
did that, would probably just cause more problems instead of solving
any).
  Of course funny things may happen if there are two PNGs in the wegpage
with *different* gamma info. (IOW, what should be done to the other
elements in the page?)

> > What is worse, if there *is* gamma info, some programs will read it, others won't.


> This certainly is no PNG standardization group's fault, some programs
> just act wrong.

  Right, but think about image formats which do not support any gamma info.
No gamma-related problems appear there.

-- 
                                                          - Warp

Post a reply to this message