Interfaces: PC and MAC and the screenGamma property...

[Scott Rossi]

On 1/2/04 3:51 PM, "Chipp Walters" <chipp at chipp.com> wrote:

> I ended up getting an iBook over the holidays to do some cross-platform
> development. Been awhile since I've used Macs for any length of time (they
> sure have changed;-0)
> 
> Anyway, I spent a few hours today trying to track down a color issue and
> here's what I found out:
> 
> If you are like me, you may use animated GIF's to create blinking lights,
> progress bars, etc.. And if you use ImageReady and Photoshop, you can create
> them easily so that the GIF overlays what's beneath it seamlessly. Your user
> will never 'see' the boundaries. But...there's a catch for cross-platform
> developers. Different images have native gamma correction built in, and this
> can create problems when combining GIFs, PNGs and JPGs.

Chipp:

An interesting observation about color, one I hadn't noticed before.  I did
a couple of quick tests over here and encountered the same issue with regard
to PNG but not BMP.  I'm at a slight disadvantage since I'm on a laptop at
the moment with an LCD screen, but the test is here:

  go URL "http://www.tactilemedia.com/colordemo1.rev"

All but the PNG image appear to be the same color here.  AFAIK, you should
not see any difference between any of the images except apparently PNG.

By any chance do you have Photoshop's/ImageReady's color management enabled
which embeds color profiles within images?  If so, then you should disable
this for the purposes of creating images for on-screen and the Web (this
feature is really only suitable for print work).

In my own work, the only time I ever use PNG is when I need to show an image
with variable translucency, or a photographic image that compresses better
than with JPG; otherwise I use GIF and JPG most frequently.  I have noticed
that solid color regions and certain gradient patterns often compress a bit
smaller using as GIF than as PNG so there's another possible reason to use
the format.

If you are running into a development obstacle with the image formats that
is preventing you from creating what you want, feel free to run it by me
off-list.  I'd be happy to take a look and help if I can.

Regards,

Scott Rossi
Creative Director
Tactile Media, Multimedia & Design
-----
E: scott at tactilemedia.com
W: http://www.tactilemedia.com