[Leica] Rudely awakened by color management

[hopsternew at gmail.com (Geoff Hopkinson)]

John there are several intertwined issues there.
Lightroom is focused mainly for digital captures which typically
have embedded profiles. The Raw processing engines know how to interpret
those (Camera Raw and Lightroom have identical engines).
If there's no embedded profile Lr assumes sRGB. Internally Lr actually uses
a very broad colour space that is similar to ProPhoto RGB *but is linear*.
That is a gamma of 1.0, not with the big curve that adjusts the files to
look 'normal' to our eyes. This is because Raw files work that way too.

When you convert Raw files into images that our eyes can understand, you
then assign the colour space that you want. The default will be whatever you
tell it to be. Many people always leave their files in the broadest possible
colour space (ProPhoto RGB) because it is just about impossible to lose any
information that way and you can make copies in any other smaller colour
space for whatever purpose you want.
 For web images the default is sRGB since monitors can display that. When
you get to web browsers, some are colour management aware as
you noted. Internet Explorer is not. Since you cannot control people's
monitor adjustments nor their browser you should convert your images to sRGB
for web viewing.

So as an example out of all of that, you might have made a photograph in Raw
in your camera, you develop it in Lightroom and export  a copy in whatever
format and colour space you choose. If you were developing the photo further
or planning to print or archive you would likely choose a large colour space
and not throw away any information (a 16 bit TIFF in ProPhoto RGB for
example). When you make a version for the web, whether from your Raw
original or that big  TIFF, you should convert your JPEG to sRGB, ideally
after you have done any other developing that you want.
 I am sure that the the acronym police will be on my case but that is as
best as I can type and explain.

Hint:There are some mini reviews on excellent resouces to learn about this
stuff on the LUG Pearls wiki ;-)

Cheers

Geoff
http://www.pbase.com/hoppyman


On 13 April 2010 01:24, John Nebel <john.nebel at csdco.com> wrote:

> This is probably old hat to many or most.
>
> When I was testing clickable "where's Waldo" pictures of the Boulder Mall,
> they looked horrible in Firefox 3.0.x on a PC, but fine on Firefox 3.6 on a
> Mac.
>
> http://photos.csd.net/spring_mall_01.html
>
> http://photos.csd.net/spring_mall_02.html
>
> This was after using ProPhoto RGB (the default?) in Lightroom which carried
> through to the web images; Adobe 1998 had not been as bad.
>
> The solution was simple for Firefox, use the URL about:config and turn on
> the
> optional gfx.color_management_enabled switch on Firefox 3.0.x.  The later
> Firefox which was running on the Mac had color management enabled by
> default.
>
> http://www.dria.org/wordpress/archives/2008/04/29/633/
> has examples of Firefox vs Photoshop.  More on:
> http://www.gballard.net/psd/go_live_page_profile/embeddedJPEGprofiles.html
>
> I can't figure out how to make Explorer behave, so one must use sRGB or be
> out of luck there?
>
> Safari does use color management on both platforms.
>
> John
>
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