Archived posting to the Leica Users Group, 2010/04/13
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Geoff, Your e-mail is very interesting and I read it carefully more than once. Thanks. Fortunately I've saved images since the beginning of digital photography in the camera's raw format except those taken with the old Leica S1. I've been careful to calibrate monitors and to be aware of color management, however, until Sunday I hadn't realized that Microsoft didn't care as much with its browser. I rarely use Explorer, but most people still do and that's what counts. I really should have known better because I went to some trouble a year ago to bring up a PC with IE 6 to test web pages with IE 6 quirks, lack of PNG support being one. John Geoff Hopkinson wrote: > 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 >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information >> > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information