Re: [APML] Reflecting on Cygnus

[Jerry Lodriguss <lists4@astropix.com>]

Hi Chuck,

First, let me ask you what version of Photoshop you are using, and what you 
have set as the working color space, and what OS you are using?



>Yes, I know there can be a big difference between color spaces. All
>I'm asking Rob is which way is he intending people to view his
>images, with the profile applied, or not.


My point was, his intentions don't matter because most people will view the 
image in a web browser that does not use color management, so they are 
going to be viewing it without the profile applied.  (unless they take the 
time to save the image and then re-open it in Photoshop to look at it, and 
provided they have color management set up correctly in Photoshop... the 
last being non-trivial). But I'm sure that the overwhelming majority of 
people are just looking at it in a web browser.





>  I asked him to perform that
>test so he could see what a big difference there was. At least I
>hoped he could see it.



As I pointed out, this test is not valid because it depends on what the 
working color space is set to in Photoshop. The image will look radically 
different depending on the size of the gamut of the color space chosen.

But, note that this is not because, as you say, there are differences 
between color spaces.  It is because the wrong profile is being applied to 
the data.

A more valid test would be to set Photoshop's working color space to the 
monitor profile, and then see what the image looks like with and without 
the sRGB color tag applied. (Note that you should never set Photoshop's 
working space to the monitor profile for real).

I did this test on a 19inch LCD and I could see only a very small 
difference between the monitor profile and sRGB. About the same amount of 
difference as between the monitor profile and sRGB on a CRT monitor.



>With more of us going to new and brighter LCD displays, the
>difference in the display gamut and sRGB is much larger than it was
>between a typical monitor and sRGB. The difference I see here is
>huge. I believe he has a new display himself and it was after he was
>using it that his images looked much different. The difference is
>mainly in brightness and not hue.


It's not surprising that there is a difference because sRGB was a kind of 
lowest common denominator for *CRT* monitors.

However, if he has an LCD display and he adjusted the image for correct 
brightness on his, and you view it on your LCD display, there shouldn't be 
that much difference, if both are set up correctly.

If you save an image as an sRGB jpeg and then open it in a browser, and 
then tile both the browser and Photoshop so you can see the image in both 
at the same time on the same monitor, be it a CRT or an LCD, there should 
not be that much difference between the two images. IF the monitor is 
correctly calibrated and has a correct monitor profile and if Photoshop and 
the OS are all set up correctly for color space management on both your end 
and on the image creator's end... which, believe me, a very difficult set 
of criteria to satisfy.

But still, your test in photoshop is not valid as you are doing it.

Jerry








_______________________________________________
Astro-Photo mailing list
Astro-Photo@seds.org
http://seds.org/mailman/listinfo/astro-photo