Re: [APML] Reflecting on Cygnus

[Jerry Lodriguss <lists4@astropix.com>]

>Well this was part of the experimentation. I used this chart to set
>the gamma as accurately as I could. Have you seen this?
>
>http://www.aim-dtp.net/aim/download/mccp_v1.4.gif
>
>The entire article is here:
>
>http://www.aim-dtp.net/aim/calibration/monitor_calibration/ 
>monitor_calibration.htm


Hi Chuck,

I hate to be the bearer of bad news, but Timo is a well known web quack. He 
is legendary. He advocates using a linear gamma, and although his site 
sounds authoritative, I would not believe anything I read there, nor would 
I use any charts that he produces to decide anything about the display of 
my monitor.

I would be much more inclined to believe something I read here:

http://www.normankoren.com/makingfineprints1A.html

about monitor gamma and calibration.

Charles Poynton also wrote the bible on gamma:

http://www.poynton.com/Poynton-color.html

Honestly,  these get too dense for me though.

You know what I use?  I use your 18 step grayscale step wedge. It's the 
greatest thing that was ever invented. And I use Adobe Gamma. And even then 
I have to cheat a bit because the display always comes out too dark with 
Adobe Gamma, I can't see the darkest steps on the step wedge.

If I was doing printing, or pre-press work professionally, I would get a 
Sony Artisan and use their hardware calibration.  But, because of the fact 
that 99.999999999 percent of the people who look at images on the web don't 
have their monitors calibrated at all, I just don't worry about it. And I 
don't even really worry about my own display as long as I can see all of 
the steps in your step wedge, which I have to thank you for turning me on 
to it because I think it is one of the best tools out there.


There's also some info here by Ian Lyons on calibrating an LCD display in 
OS 10:

http://www.computer-darkroom.com/colorsync-display/colorsync_3.htm







>The gamma needs to be set to 1.3 for this display for the best
>results on that gamma calibration chart. I suppose that's not a
>surprise since LCDs are supposed to be more linear than CRTs. They
>should require less gamma correction.


well, like I said, don't trust this chart.



>This highlights a problem between LCDs and CRTs for on-line viewing.
>Even though there were variations between CRTs, they weren't that
>great. The color gamuts weren't hugely different and the gammas
>weren't either. This probably accounts for why something done on one
>monitor looked passable on another, especially if both had been
>calibrated, even without color management.
>
>Now along comes an LCD with a hugely different gamma correction. Non
>color managed images generated using a CRT look like crap on it when
>viewed in monitor space.


I think the problem you may be running into is the old Mac gamma of 
1.8.  It's just not valid or used anymore.

On the LCDs I use, I just don't see that much of a difference.  I'm on a 
Windows platform though. More hints of evidence that it's a mac gamma thing.

1.3 definitely does not sound right, it's too close to linear (which is 
what Timo preaches).

Here's the evidence... the numbers don't add up... you got info from Timo, 
you see vast differences in the displays between your new LCD and your old 
CRT. It really sounds like you don't have something set up right.

Ian Lyons says "The majority of displays (CRT and LCD) will have a Native 
gamma somewhere between 2.0 and  2.2 "






>Color Sync provides some nice graphical data for each profile in the
>system. I screen shot a couple of these.
>
>Colorant Tristimulus for the Dell 2405FPW, sRGB EIC61966-2.1, Adobe
>RGB 1998
>
>http://images.aa6g.org/colorant tristimulus.jpg
>
>You'll see right away that the 2405 color gamut is almost identical
>to sRGB.
>
>
>Red Gamma Curve for the Dell 2405FPW, sRGB EIC61966-2.1, Adobe RGB
>1998 (green & blue are virtually identical to red)
>
>http://images.aa6g.org/response curve.jpg
>
>This is where the difference is.


The problem is the 1.3 gamma.



>this is a new problem. Every unmanaged color image on the internet
>generated by looking at a CRT monitor looks washed out on this
>display in monitor space. So unless I use Safari and hope that images
>have a profile with them, any image I care about is going to look poor.


I'm tempted to say that the lesson here is to stick with CRTs. :-)

But, I use Mac laptops with LCDs and Windows desktops with LCD screens, and 
everything looks ok here, so...






>Now that I have the best calibration on my monitor that I know how to
>perform, I really need to view images with Photoshop in sRGB working
>space.... and save them with the embedded profile to remain
>compatible with the CRT world.


You can soft proof them. But, you should convert them to sRGB before saving 
as a JPEG for the web. I don't worry about tagging the images because 98 
percent of the browsers out there ignore the tags.  Windows uses sRGB as 
the default on a system level anyway, so as long as they are converted 
first, they don't have to be tagged.



>Seems like every time a new and more advanced piece of technology
>comes along it reveals existing but mostly unrecognized problems.

Amen to that.



>So although this display has only the color gamut of sRGB, it
>produces a brighter, higher contrast and sharper image.

I guess that's why you and Rob think it shows more of the imperfections of 
an image, another reason not to use em :-).

Personally, I really hate the way LCDs look, but my kids love them. They 
have young eyes. I guess that tells you something.

Jerry




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