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Photo Forum / Digital Photography / DSLR Cameras / February 2006

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Adjusting contrast for digital projectors

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Paul Furman - 02 Feb 2006 00:07 GMT
I'm preparing some photos for a slide show on a digital projector and I
know those awful things boost contrast so I'm thinking of reducing
contrast on the images.

My projector bulb is burned out at the moment though so I can't test.
Maybe someone can test this or already knows the appropriate adjustment.
I think it's more a matter of blocking up shadows than blowing
highlights (though I'm not sure) so maybe with a photoshop levels
adjustment on the lower 'output' slider to cut off to 50-255 (starting
at 0-255).

Or will this even work? It's a shame to see the photos butchered on
those projectors!
C J Southern - 02 Feb 2006 00:54 GMT
I don't use a projector, so I can't help with your original question, but
you may or may not know that the Spyder2Pro Studio kit comes with all the
necessary evils to profile your projector so you wouldn't have any of these
issues in the future.
Mike Russell - 02 Feb 2006 00:54 GMT
Have you tried running Adobe Gamma using the projected image as a reference?
If this is not available, the display driver may have a gamma adjustment.
The location of the display control panel depends on whether you are using a
Mac or PC.
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Mike Russell
www.curvemeister.com

Paul Furman - 02 Feb 2006 01:22 GMT
> Have you tried running Adobe Gamma using the projected image as a reference?
> If this is not available, the display driver may have a gamma adjustment.
> The location of the display control panel depends on whether you are using a
> Mac or PC.

The projector to be used is a mac, mine is a pc. Is this something that
can be adjusted on the computer? I doubt his has adjustment in the
projector, mine doesn't & his is smaller. I think they make them high
contrast so it works in a partly lit room like for business meetings.
Mike Russell - 02 Feb 2006 02:46 GMT
>> Have you tried running Adobe Gamma using the projected image as a
>> reference? If this is not available, the display driver may have a gamma
[quoted text clipped - 5 lines]
> projector, mine doesn't & his is smaller. I think they make them high
> contrast so it works in a partly lit room like for business meetings.

I'd recommend that you install Adobe Gamma on the Mac, if you have access to
the Mac version.  Run it in wizard mode, and try to adjust it according to
the instructions.  If you can get things looking good - and there are no
guarantees - you're set.  Another possibility is to use the display control
panel - some drivers have adjustments for gamma and/or brightness and
contrast.

Another trick I've heard of - from Andrew Rodney - is using the Eye One
Color.  It's designed to be used with a CRT or an LCD, but if you point it
backwards, it can be fooled into calibrating a projector.  Cool, huh?

If you post the model number of the projector, someone may post with more
direct experience.
Signature


Mike Russell
www.curvemeister.com

John Forest - 02 Feb 2006 16:13 GMT
Our camera club just purchased a digital projector.  We ran Adobe Gamma and
the pictures still looked too contrasty.  We ran it again, this time
ignoring the first step prescribed by the wizard, to set the monitor to the
maximum contrast.  We put the contrast (using the projector controls) back
to the default value.  (It allows plus or minus settings up to 14.)  We then
did the rest of the setup as called for in Adobe Gamma, with the box
unchecked for "view single gamma only"  We found it helpful to defocus the
projector slightly when doing the setups for red, green and blue.  With the
setup this way the pictures were a very close match to what was seen on the
monitor.  Another thing we found was that the projectors have a very short
projector to screen distance and it is tempting to angle it upward and use
the keystoning control to make the picture rectangular.  That results in the
bottom of the screen being much lighter than the top.  We took steps to
raise the projector so it is parallel to the screen to solve this problem.
J. A. Mc. - 02 Feb 2006 17:21 GMT
>Our camera club just purchased a digital projector.  We ran Adobe Gamma and
>the pictures still looked too contrasty.  We ran it again, this time
[quoted text clipped - 10 lines]
>bottom of the screen being much lighter than the top.  We took steps to
>raise the projector so it is parallel to the screen to solve this problem.

Better projectors have allowed for this with a lens shift mechanism, similar
to Perspective Control lenses or a swing lens in a portrait camera.

Projection and Video 'space' is different from monitor space as far as
levels go.
Paul Furman - 02 Feb 2006 18:13 GMT
>>Our camera club just purchased a digital projector.  We ran Adobe Gamma and
>>the pictures still looked too contrasty.  We ran it again, this time
[quoted text clipped - 16 lines]
> Projection and Video 'space' is different from monitor space as far as
> levels go.

My projector is a Dell 2300MP. Holy sh.t, the replacement bulb is $350!
Anyways it defaults to keystone correction assuming it's pointing up
from a conference table and that's adjustable in the menu but any
adjustment in the menu seems to put it into instability causing the
image to drift to the side & requiring 'reset-all' to fix. When I get
another bulb I'll see if it's possible to adjust contrast for profiling.
http://www.projectorcentral.com/Dell-2300MP-user-reviews.htm
http://www.pcmag.com/article2/0,1759,1710890,00.asp
J. A. Mc. - 03 Feb 2006 17:43 GMT
>>>Our camera club just purchased a digital projector.  We ran Adobe Gamma and
>>>the pictures still looked too contrasty.  We ran it again, this time
[quoted text clipped - 25 lines]
>http://www.projectorcentral.com/Dell-2300MP-user-reviews.htm
>http://www.pcmag.com/article2/0,1759,1710890,00.asp

Sorry, I don't have the tech setup papers for any Dell machines.
If it 'defaults' to keystone correcting, then there's no lens shift.

That price on the bulb is 'cheap' - the ones we use are $800 to $1500! <G>
When you consider that slide projector bulbs last about 30 hours and run
$20, you should be paying double that for your 1,000 hours. <G>
J. A. Mc. - 02 Feb 2006 00:56 GMT
>I'm preparing some photos for a slide show on a digital projector and I
>know those awful things boost contrast so I'm thinking of reducing
[quoted text clipped - 9 lines]
>Or will this even work? It's a shame to see the photos butchered on
>those projectors!

If you have a friend with a laptop and an LCD screen you can approximater
the butchery.

FWIW, I'd go with a gamma or curve adjustment, not contrast!

IF you've got a good projector, it too will have a gamma option - perhaps
you can get the setup tech to use it. Furnish a 16 step greyscale as a
'test'.
Paul Furman - 02 Feb 2006 01:19 GMT
>>I'm preparing some photos for a slide show on a digital projector and I
>>know those awful things boost contrast so I'm thinking of reducing
>>contrast on the images.

My friend is going to show them on his projector, I know it boosts
contrast similar to mine and I don't think there is any adjustment. I'll
probably not be able get him to set it up for tests in the evening.

> If you have a friend with a laptop and an LCD screen you can approximater
> the butchery.
>
> FWIW, I'd go with a gamma or curve adjustment, not contrast!

Hmmm, gamma is more like the brightness of middle tones and I think the
issue is really contrast. Middle tones are probably about correct but
colors get oversaturated & shadows blocked up.

> IF you've got a good projector, it too will have a gamma option - perhaps
> you can get the setup tech to use it. Furnish a 16 step greyscale as a
> 'test'.
J. A. Mc. - 02 Feb 2006 17:18 GMT
>>>I'm preparing some photos for a slide show on a digital projector and I
>>>know those awful things boost contrast so I'm thinking of reducing
[quoted text clipped - 16 lines]
>> you can get the setup tech to use it. Furnish a 16 step greyscale as a
>> 'test'.

Video Gamma is a bit different than photoshop's 'gamma'. It's used to
stretch the black areas and lightly compress the upper highlights.

Don't forget too, that photographic imagery goes to "0" black. Video cameras
never go below "20". Also Video camera "white' is really more like "224".
The video space allows higher levels, but they are for reflections and often
are clipped. LCDs exacerbate the clipping 'look'.
 
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