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Recommended monitor luminance levels?

 
 
Kulvinder Singh Matharu
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      03-11-2008
On Mon, 10 Mar 2008 23:44:28 +0000 (UTC), Ilya Zakharevich
<(E-Mail Removed)> wrote:

[snip]
>
> 90 * (8/5)**2 * 80/25 = 737.28
>
>The documented value on the manufacturer's site is: Brightness 500
>cd/m2. I'm using factory preset brightness.
>
>WHY would one use less than "the factory preset"?
>
>Yours,
>Ilya


If you're not using about 90 cd/m2 then you're going to have some
real problems using various manufacturer supplied printer/paper
profiles as they apparently assume 90 cd/m2 luminance. At 200 cd/m2
then prints will look dark unless you create custom profiles.

Lots of monitors these days are set at insanely high luminance levels
as that appears to sell. I'm not sure what my monitor's factory
default luminance level was but it was so bright that I had to squint
at the screen! I immediately lowered the luminance down to about 190
cd/m2 but have now realised that it wasn't enough!

--
Kulvinder Singh Matharu

Website : www.MetalVortex.com
Contact : www.MetalVortex.com/contact

Blog : www.MetalVortex.com/blog
Experimental : www.NinjaTrek.com

Brain! Brain! What is brain?!
 
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Ilya Zakharevich
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      03-11-2008
[A complimentary Cc of this posting was sent to
Kulvinder Singh Matharu
<(E-Mail Removed)>], who wrote in article <(E-Mail Removed)>:
> >WHY would one use less than "the factory preset"?


> If you're not using about 90 cd/m2 then you're going to have some
> real problems using various manufacturer supplied printer/paper
> profiles as they apparently assume 90 cd/m2 luminance. At 200 cd/m2
> then prints will look dark unless you create custom profiles.


Maybe I have some mind blocks, but I just cannot grasp what people
mean when they say that "print matches what I see on the screen".
What I see on the screen is affected (although only near black) by the
incoming light. What I see on the print is affected MAJORLY by the
incoming light.

Do "the manufacturers" assume that I will use my blueish flashlight to
illuminate the print? My overhead lamp? Open the sunshades? My
table light?

> Lots of monitors these days are set at insanely high luminance levels
> as that appears to sell.


What is "insanely high"? Whatever is not covered by profiles, or do
you mean anything else? (As you can guess from my misunderstandings,
I do not use profiles...)

> I'm not sure what my monitor's factory
> default luminance level was but it was so bright that I had to squint
> at the screen!


Well, everybody in the house is very satified that this LCD is
brighter than the old (slowly dying) CRT.

Puzzled,
Ilya
 
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Kulvinder Singh Matharu
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      03-11-2008
On Tue, 11 Mar 2008 21:27:17 +0000 (UTC), Ilya Zakharevich
<(E-Mail Removed)> wrote:

[snip]
>What is "insanely high"? Whatever is not covered by profiles, or do
>you mean anything else? (As you can guess from my misunderstandings,
>I do not use profiles...)
>
>> I'm not sure what my monitor's factory
>> default luminance level was but it was so bright that I had to squint
>> at the screen!

>
>Well, everybody in the house is very satified that this LCD is
>brighter than the old (slowly dying) CRT.


That's fine, but as you've guessed my issue is all about getting
print-monitor matching:

http://people.csail.mit.edu/ericchan...ay_calibration

--
Kulvinder Singh Matharu

Website : www.MetalVortex.com
Contact : www.MetalVortex.com/contact

Blog : www.MetalVortex.com/blog
Experimental : www.NinjaTrek.com

Brain! Brain! What is brain?!
 
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David J. Littleboy
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      03-12-2008
"Ilya Zakharevich" <(E-Mail Removed)> wrote:
> Kulvinder Singh Matharu :
>
>> Lots of monitors these days are set at insanely high luminance levels
>> as that appears to sell.


FWIW, this is my impression as well. The last time I was at a friend's
house, I was horrified at how bright my pbase gallery images looked on said
friend's screen.

> What is "insanely high"?


On current LCD screens, anything over "0", apparently.

>Whatever is not covered by profiles, or do
> you mean anything else? (As you can guess from my misunderstandings,
> I do not use profiles...)


On my Dell 19" LCD, I have to turn the brightness down to zero to be able to
adjust the screen using Adobe Gamma. This leaves the screen a bit dark for
my (non-photogrphic) work, so I turn it up to 20 (out of 100) when I'm not
doing photography. (Contrast gets set at maximum.)

>> I'm not sure what my monitor's factory
>> default luminance level was but it was so bright that I had to squint
>> at the screen!

>
> Well, everybody in the house is very satified that this LCD is
> brighter than the old (slowly dying) CRT.


Well, there you go: the people around you like a bright screen. My
impression is that this is common.

But with a bright screen, the shadow areas in images look a lot brighter and
clearer on the screen than they will look in a print, so what looks good on
the screen will have unacceptably blocked up (dark) shadows on the print.
Turn down the brightness on the screen, increase the brightness (either
exposure compensation, brightness, or the middle slider in Photoshop Levels)
in the image editor, and the shadows on the print will be a better match to
what's on the screen.

As you pointed out (in the section I snipped), prints and screens are
affected differently by the ambient light levels. But it's even worse than
that: my take is that the mechanisms by which these technologies generate
images (paper sucks photons and screens spit photons) that trying to make
tham match is pretty hopeless.

(Please don't send me private email.)

David J. Littleboy
Tokyo, Japan


 
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Ilya Zakharevich
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      03-12-2008
[A complimentary Cc of this posting was NOT sent to
David J. Littleboy
<(E-Mail Removed)>], who wrote in article <(E-Mail Removed)>:
> On my Dell 19" LCD, I have to turn the brightness down to zero to be able to
> adjust the screen using Adobe Gamma. This leaves the screen a bit dark for
> my (non-photogrphic) work, so I turn it up to 20 (out of 100) when I'm not
> doing photography. (Contrast gets set at maximum.)


Do you mean that your LCD is saturated near levels 0xFF on the rest of
brightness levels? Mine is not.

I have no problem setting gamma to 2.2 with the default brightness.
The number of "graylevels eaten" near 0xff is what I expect with
1%-rule. (Since my display driver allows storing [and loading? - I did
not test custon tables, just one-floating-point-gamma-value] a
16-bit-per-color-per-256-levels translation table for brightness, I do
not see how gamma tuning could have been affected by the brightness
setting without saturation near 0xFF.)

> But with a bright screen, the shadow areas in images look a lot brighter and
> clearer on the screen than they will look in a print, so what looks good on
> the screen will have unacceptably blocked up (dark) shadows on the print.


IIUC, what you say is essentially: nowadays, the display is a much
better presentation media than photographic paper. So let dumb it
down so it is not better than photographic paper. Right?

> Turn down the brightness on the screen, increase the brightness (either
> exposure compensation, brightness, or the middle slider in Photoshop Levels)
> in the image editor, and the shadows on the print will be a better match to
> what's on the screen.


I would gradly do this on AS NEEDED basis, not as default. (What I'm
doing with prints now is just a correction with gamma=0.75 immediately
before sending them for print...)

Thanks,
Ilya
 
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David J. Littleboy
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      03-12-2008
"Ilya Zakharevich" <(E-Mail Removed)> wrote:
>
>> But with a bright screen, the shadow areas in images look a lot brighter
>> and
>> clearer on the screen than they will look in a print, so what looks good
>> on
>> the screen will have unacceptably blocked up (dark) shadows on the print.

>
> IIUC, what you say is essentially: nowadays, the display is a much
> better presentation media than photographic paper. So let dumb it
> down so it is not better than photographic paper. Right?


A good print is a thing of amazing beauty, and screens are nowhere close. So
to say screens are better is pretty odd<g>.

But, no. I'm saying that if you have an image that has dark blocked up
shadows, you should fix that in Photoshop, not in the monitor.

>> Turn down the brightness on the screen, increase the brightness (either
>> exposure compensation, brightness, or the middle slider in Photoshop
>> Levels)
>> in the image editor, and the shadows on the print will be a better match
>> to
>> what's on the screen.

>
> I would gradly do this on AS NEEDED basis, not as default. (What I'm
> doing with prints now is just a correction with gamma=0.75 immediately
> before sending them for print...)


Here's a reality check. You can download the MacBeth color chart. You can
print it out with a roughly correctly profiled printer and it'll look very
close to just like it does in the books. It ought to look that way on the
screen, too.

A value in an image file (in a given color space) means a specific color and
density (or color and luminance). The gamut (including luminance) of each
output device is different, but for values within the gamut of the paper,
what you see on the screen ought to be the same.

So the brightness setting on the monitor ought to be such that the values
that are in-gamut for the printer ought to be displaying as close to
identically as possible on the screen.

Inversely, if the screen's gamut is way wider than, say, Adobe RGB, you
shouldn't be expanding the gamut to match the screen when you display it.

David J. Littleboy
Tokyo, Japan


 
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John McWilliams
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      03-12-2008
Ilya Zakharevich wrote:
> [A complimentary Cc of this posting was NOT sent to
> David J. Littleboy


Ilya-

As I have pointed out, I doubt that any NG regular wants "cc's" however
called. Please desist.

Although maybe a string of fellows will post exceptions.

--
john mcwilliams
 
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Ilya Zakharevich
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      03-12-2008
[A complimentary Cc of this posting was NOT [per weedlist] sent to
David J. Littleboy
<(E-Mail Removed)>], who wrote in article <(E-Mail Removed)>:
> A value in an image file (in a given color space) means a specific color and
> density (or color and luminance).

^^

That "or" makes, IMO, your statement completely useless, since there
is no way to translate density to luminanance (e.g., I have 4
different light sources near my monitor).

> what you see on the screen ought to be the same.


As I said, I have no idea what people MEAN when they say that "image
on paper is the SAME as on the screen".

> So the brightness setting on the monitor ought to be such that the values
> that are in-gamut for the printer ought to be displaying as close to
> identically as possible on the screen.


At the moments when you do the final preparations for print - maybe.
(So one may need to instruct their picture viewer to temporarily reset
the monitor colormap.) As a permanent step - I see no point.

As I said, I do just the opposite: I optimize for view, then do a
PRECALCULATED transformation (a certain gamma correction) to fit the
image into the narrower gamut of the printer. (Your solution should
give better results, mine is better for my eyes.

Thanks,
Ilya
 
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Ilya Zakharevich
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      03-13-2008
[A complimentary Cc of this posting was NOT [per weedlist] sent to
Ilya Zakharevich
<(E-Mail Removed)>], who wrote in article <fr4h4s$2vmm$(E-Mail Removed)>:
> > >Thanks. But this puzzles me; at ISO100, this would be f/5 and 1/25
> > >sec. Mine is f/8 with f/80, which gives about 740 cd/m2...

>
> > What was the calculation that you used?

>
> 90 * (8/5)**2 * 80/25 = 737.28
>
> The documented value on the manufacturer's site is: Brightness 500
> cd/m2. I'm using factory preset brightness.


One more reference point: the exposure reading from a piece of white
paper near the monitor, using my "prefered" light source, is 1/60sec
f/7.1 at ISO100. Which means that my monitor is about 70% brighter
than paper.

Yours,
Ilya
 
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Ilya Zakharevich
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      03-13-2008
[A complimentary Cc of this posting was NOT [per weedlist] sent to
David J. Littleboy
<(E-Mail Removed)>], who wrote in article <(E-Mail Removed)>:
> > IIUC, what you say is essentially: nowadays, the display is a much
> > better presentation media than photographic paper. So let dumb it
> > down so it is not better than photographic paper. Right?


> A good print is a thing of amazing beauty, and screens are nowhere close. So
> to say screens are better is pretty odd<g>.


Resolution-wise, screens are awful. But the dynamic range is so much
better...

(Of course, there are exceptions. The big TV screen I see gives quite
impressive results - if one forgets that the DVD player cuts off about
20 brightness points on top and on the bottom of the 8-bit range of JPEGs.
AND, to add insult to injury, it does in the "main view" mode only;
the preview "icon" is fine... I thing the icon is about 500x300; main
view is of the full 2MPx3 resolution.)

Puzzled,
Ilya
 
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