ADOBE RGB vs SRGB.

EdinburghGary

EdinburghGary

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Gary
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Please see this image:
http://www.talkphotography.co.uk/forums/showthread.php?t=244061

And the histogram for two versions.
redchannel.jpg


The first Histrogram is my Adobe RGB red channel for the TIFF image.

The second Histogram is my SRGB red channel for my "Save for web" Jpeg.

My question is simple. Can I display the missing data which is evident in the histogram, online? The reality is very clear. Imagine you had a layer mask, one with a white cheek, one with a retained peach. Switch the layer on and off, it's extremely obvious.

My pro printer uses Adobe RGB....

When I save my JPEGS, I use Photoshops "Save for web" option and always ensure "Convert to SRGB" is ticked...

Gary.
 
I try not to use save for web as I like to leave the exif on my image.

I don't know if save for web strips some more data from the image.
 
The colorspace is embedded into the JPEGs so in THEORY people with a properly color managed OS + browser and calibrated screen can see them. I'd bet that most people even here on the forum don't have all the versions right and settings set for that though. so in PRACTISE, it's going to be very hit & miss.

I think Firefox has been colorspace enabled for a while, and recently they changed the default from 'disabled' to 'tagged only' meaning that everything that isn't tagged is rendered in sRGB but tagged files work ok. Not sure about other browsers but Safari & Chrome on the Mac seem to also obey tags when tested at:

http://www.gballard.net/psd/go_live_page_profile/embeddedJPEGprofiles.html#

Check it out..

Color management in WinXP and its browsers was such a royal pain that I'm loving the Mac.. hopefully they've gotten it right in W7.
 
I agree, I use win XP and FF and it used to show a difference. Do you know how I can look at my settings?
 
Tom-I-think, type "about:config" into the URL field, bypass the warning, then put "gfx.color" into the search. Google for what the parameters do.

Easiest is to upgrade to the newest FF, it seems to get it right at least on a Mac.
 
There are different algorithms for compressing the colour space from adobe rgb down to srgb. These should have an effect...
 
My understanding is that the gamuts are different, therefore there will almost always be areas in any adobe rgb file that cannot be displayed on a monitor hence the missing data in the sRGB histogram.
 
All monitors are not created equal, I have an extended color gamut Dell , although I think they specify it as 92% of NTSC gamut or something. But it's definitely a bigger one than sRGB. Which is great in properly color managed apps and horrid in those that aren't. I only use it as my secondary monitor for office work but when Aperture opens up, it uses that one for a full screen image of whatever photo is selected. Mmm..
 
vaizki said:
All monitors are not created equal, I have an extended color gamut Dell , although I think they specify it as 92% of NTSC gamut or something. ..
Click to expand...

NTSC = National Television System Committee. It the system of analog television system used in USA, not sure what it has to do with colour space UK has PAL
 
jim_j said:
My understanding is that the gamuts are different, therefore there will almost always be areas in any adobe rgb file that cannot be displayed on a monitor hence the missing data in the sRGB histogram.
Click to expand...

Yes but most conversion algorithms don't just clip unreproducible areas of tone, but remap and/or compress them so you still see detail in the tones, but they do it in different ways.

I think Gary you need to try some different ones (algorithms) to get the results you want in sRGB.

Another approach may be to tweak the colours in Adobe RGB space so everything present in the image can be faithfully reproduced in sRGB, then simply clip the gamut to sRGB rather than a remap with less control. Does that make any sense or am I just babbling? :banana:
 
tiler65 said:
I try not to use save for web as I like to leave the exif on my image.
Click to expand...

So, tell the Save for Web dialogue to preserve your EXIF information? :)

saveforwebmeta.jpg
 
Test for above




Tried what you wrote John (have tried it before mind too)

Can you see any exif in the above shot?

Let me know because I certainly can't.
 
Camera Maker : Canon
Camera Model : Canon EOS30D
Lens: EF70-200mm f/4L USM
Image Date: 2010-04-17 16:43:27 +0100
Focal Length: 81mm
Aperture: f/8.0
Exposure Time: 0.0013s (1/800)
ISO Equiv: ...

Aww hell... easier to just link it. :)

Remember, "Save for Web and Devices" is specifically designed to save as much filesize in your image as possible (it's kinda the point). So by default it does strip everything.
 
The EXIF plugin I'm using shows it from within FireFox.

FxIF 0.4.1. It tells me...

Camera Maker: Canon
Camera Model: Canon EOS 30D
Lens: EF70-200mm f/4L USM
Image Date: 2010-04-17 16:43:27 +0100
Focal Length: 81.0mm
Aperture: f/8.0
Exposure Time: 0.0013 s (1/800)
ISO equiv: 320
Exposure Bias: none
Metering Mode: Matrix
Exposure: shutter priority (semi-auto)
White Balance: Auto
Flash Fired: No (Manual)
Color Space: sRGB IEC61966-2.1
Photographer: Tom Astley
 
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