Paul Thompson wrote:

> I am on PCs using 6500k and 2.2 gamma. The monitor is calibrated, the
> histograms are fine. The black point is around 8/8/8 with white around
> 244/244/244

Sounds ok.
> 
> I'm producing tiffs for agencies.
> 
> Alamy and Corbis seem happy enough with my files but my French agency has
> said that they are much too light (on their computers and for their clients)
> and I need to change the monitor gamma to 1.8 so as to produce "darker"
> images.

Ok, my bet is they are using a Mac, and are viewing the images in a non
colour managed application (a browser probably).
If you, in Photoshop, choose View > Proof Setup > Macintosh RGB you should
see what they are seeing (something lighter than what you have now).
What you see in this way however isn't nessesarily correct; if you convert
the images in a colour management savvy application this will use the
embedded profile as source space for a conversion...

> I'd appreciate it if it could be explained how these two gamma settings can
> be used on different computers/images and sit happily side by side on the
> client's digital lightbox?

It doesn't matter one bit which you choose as long as you use a colour
managed application. If you have a Mac calibrated & profiled to Gamma 1.8
and a PC to G 2.2, and display the same image in Photoshop, they will look
almost identical.
If you view them in a non colour managed web-browser the 1.8 gamma
calibrated Mac system will display the images lighter than the PC.

If you calibrate/profile your monitor to a gamma setting that differs from
the monitors native gamma, you will have a higher degree of banding, but
apart from this any CM aware application will display the images with
similar density.

Non CM savvy apps is an entirely different matter, and I'd believe that's
what they are judging from.

I'm guessing you are supplying images in either Adobe RGB (1998) or sRGB
(both are Gamma 2.2 working spaces). Rather than touching your (hopefully
calibrated and profiled) monitor, try to convert your RGB files to either
ColorMatch RGB or Apple RGB (both are Gamma 1.8 working spaces). Ask the
agency if this is better. On a profiled system in a CM aware application
most images will look identical, but in a browser on a mac it will make a
difference.

If this doesn't do the trick, convert a bunch of your images to Euroscale
CMYK v2 and have an analogue cromalin or MatchePrint done. If this looks
correct to you (looks like your monitor) send it to the agency and tell them
this is what happens when you convert your images to CMYK. Ask if this is
what the images looks like on their screens. If not, it's their system...

Best Regards

Thomas Holm / Pixl ApS

- Photographer & Colour Management Consultant
- Adobe Certified Training Provider in Photoshop�
- Apple Solutions Expert - Colour Management
- Imacon Authorized Scanner Training Facility
- Remote Profiling Service (Output ICC profiles)
- Seminars speaker and tutor on CM and Digital Imaging etc.

- Home Page: www.pixl.dk � Email: th[AT]pixl.dk
-- 


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