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Calibration "conceptual" problem

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  #1  
Old 06-12-2014, 08:23 AM
frankg frankg is offline
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Calibration "conceptual" problem

I have a 'conceptual' difficulty around display calibration that I just cant get my head around. I hope I can ask this question and have it explained to me on a 4 year old child's level :-)

I understand that the Luminance / Brightness target is not an 'absolute' value like Gamma 2.2 and WP 6500K are more or less 'Standards' for just about everyone. Or at least for Most people (6500 transmitted light seems to roughly equal 5500 reflected light, but I digress)
Luminance can be different for everyone and is affected by the ambient light levels / conditions one is working in, and the light source used to evaluate prints.

But what if either I am not printing myself but sending files to a lab for printing, or I am displaying my images on the web - how can I be certain that you are seeing the same image & brightness for the image/s that I have prepared on my monitor at my target/current values? Even though the image profiles are embedded i.e. I use AdobeRGB(1998) for almost all my work and sRGB for web display.

I realize this is probably an elementary notion to you but I can't understand it.
If all the target values were an 'absolute' then it would be easier to understand that everyone with a calibrated display is seeing the exact same thing.
But, for example, if my targets/current vales are 6500k, 2.2, & say 115 cd/2 and yours are 6500k, 2.2, and say 90cd/2 surely the same image would look different ? Especially if another value e.g. WP is Also different

Any clarification would be much appreciated,
Frank
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Old 06-12-2014, 09:12 AM
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andrewrodney andrewrodney is offline
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Re: Calibration "conceptual" problem

Quote:
But what if either I am not printing myself but sending files to a lab for printing, or I am displaying my images on the web - how can I be certain that you are seeing the same image & brightness for the image/s that I have prepared on my monitor at my target/current values?
You can't. Unless they calibrate to the same targets as you do, with the same display, software and instrument, the visual results will not be identical (they can be very close). And if other's are not using ICC aware applications, the previews they see are likely way off.

The main task for display calibration is to produce WYSIWYG such a print next to the display, under controlled illuminant matches the soft proof of the image on that display next to the print.

Quote:
if my targets/current vales are 6500k, 2.2, & say 115 cd/2 and yours are 6500k, 2.2, and say 90cd/2 surely the same image would look different ?
Probably. The white point is the biggest factor, the backlight intensity far less, the gamma settings have no bearing at all in color managed applications. Your eye's adapt to white and luminance pretty well. They two display systems would have to be next to each other, both within view for you to 'see' a mismatch (or match).
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Old 06-19-2014, 02:30 PM
frankg frankg is offline
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Re: Calibration "conceptual" problem

I'm still grappling with the problem of calibrating in such a way that there is some kind of 'standard' for 'talking to others' and us all seeing the same image. This continues to baffle me.

I bought a new monitor and calibrated it WP 6500, gamma 2.2, and a Luminance of 110 cd/m2 (which seems to be close for wyswyg prinnting on my epson 3880 using paper profiles. Although I may tweak the luminance down a bit.

Here's the problem. I just did a series of 22 portraits and after photoshopping them to look as I wanted, on my new monitor (they're in black & white), I shipped them off to the graphic designer who is designing a composite and having the piece printed. He said they were a bit dark (light areas) and that he needed to tweak them a little in Levels.

Obviously i don't know how he has calibrated his monitor, I think he is on a MacBook Pro, but surely there must be a way to 'standardize'.
Wyswyg from my monitor to my printer is important but not nearly as crucial as me being able to send out files to others across the universe and needing some kind of method to know that they are going to get and see what I intend them to see.

Is there no way to do this....what am I missing ?
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Old 06-19-2014, 02:39 PM
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andrewrodney andrewrodney is offline
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Re: Calibration "conceptual" problem

There is no standard. There are all kinds of displays out there with differing technologies. There are differing calibration solutions. You want a group to see the same numbers identically? Get them all a reference display system (NEC PA series), all running SpectraView set to the same calibration targets. Measure using the same instrument. They should see the same numbers identically if you also control the viewing environment. Short of that, all bets are off.

If the designer thinks his display system is so great, let him tweak the files and let's see what comes out from the output.
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Old 06-20-2014, 03:00 AM
klev klev is offline
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Re: Calibration "conceptual" problem

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Originally Posted by frankg View Post

I bought a new monitor and calibrated it WP 6500, gamma 2.2, and a Luminance of 110 cd/m2 (which seems to be close for wyswyg prinnting on my epson 3880 using paper profiles. Although I may tweak the luminance down a bit.
Keep in mind that what you see can still vary somewhat by viewing conditions. You might be best off if you sent prints for reference.
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Old 06-20-2014, 11:05 AM
insmac insmac is offline
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Re: Calibration "conceptual" problem

Forget about getting the images to look good on all systems, especially the web. It's a dead end. Seriously, forget it.

Mainstream IPS panels might be rich in contrast in lower end range, hence the alleged "lack of details in shadow" seen by the designer. You can't even assume two iMacs produce the same output. And the working environment, of course. No two desks are the same, so to speak (unless of course you have that under control but we're talking an average user, not a post facility).

I have a friend who does a lot of high end print stuff (movie/opera posters and such) which also appears online (press releases and so on). In addition to a rigorously calibrated Lacie he has a pretty cheap mainstream Samsung TN panel which does an excellent job providing a visual reference of how your picture will present itself on a crappy display.
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Old 06-25-2014, 09:21 AM
Rovanpera Rovanpera is offline
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Re: Calibration "conceptual" problem

the more ambient light there is in the room, the lighter the black on the display will be, and you should compensate that with higher brightness, to maintain the contrast. The recommended brightness of around 100 cd is meant for a quite a dark viewing environment.

There is an ISO standard for proofing, gamma 2.2, 5000k and 100cd, and a neutral dark room with indirect lighting (there is a recommended ambient light level for the room, but I don't recall it now). Nowadays it's just practical to use 6500k because that is the native color temperature of the lcd's, and most screens are set to 6500k.
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Old 06-25-2014, 11:58 AM
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andrewrodney andrewrodney is offline
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Re: Calibration "conceptual" problem

There is an ISO 'standard' but don't expect those settings to produce a visual match to the print. Impossible without having specific viewing conditions or YMMV. The biggest factors that affect mismatch is first the white point, then the backlight intensity. They have to be set to produce a visual match and your settings will likely vary. Gamma in color managed app's is immaterial, go ahead and use 2.2 or Native if the software supports it.
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Old 06-25-2014, 01:22 PM
Rovanpera Rovanpera is offline
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Re: Calibration "conceptual" problem

Forgot to mention that this is with professional grade calibrated screens.
But what it means is that professional setups should be calibrated to a certain standard so that everyone with that setup should see the same thing.

There's an ISO standard for viewing the prints as well, on a booth with high quality 5000K light and intensity to match the screen.

I used to have a setup like this and my screen was matching my proofs well, and things looked the same at the printing houses I was using as well. I set it up myself, calibrated the screens and printers, and was happy with the accuracy.

But as Andrew stated already, different setups can come close to each other, but in the real world there will always be a lot of variation.
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Old 06-25-2014, 11:04 PM
klev klev is offline
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Re: Calibration "conceptual" problem

Quote:
Originally Posted by Rovanpera View Post
There's an ISO standard for viewing the prints as well, on a booth with high quality 5000K light and intensity to match the screen.
That standard is very expensive to properly set up. It's also costly purchasing a display that can be calibrated to 5000K without causing problems, meaning poor greyscale tracking where some neutral values in the range look yellowish and maintaining an image that is free of banding. You might note that they recommend a 160cd/m^2 display brightness. It is meant to match a very bright viewing booth with minimal extraneous light. Of course displays lose brightness over time, so you will have to replace that display earlier than you might otherwise, due to the shorter half life from running at that brightness level.
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