color management - why custom?

[dmitry_a]

Reading up on color management leaves an impression that people are

just dragging their old habits into the new brave world of digital.

 

1. Why calibrate the monitor? An LCD panel of a known manufacturer

that is being fed digital signal from the computer should have a well

known profile available from the manufacturer. Is there much

physical variation between two panels of the same model coming from

the same assembly line?

 

2. Isn't it what people a paying good money to Epson for - their inks

and papers being as consistent as possible, and therefore color

profiles being well known?

 

How is it done in the Apple world? If I buy an iBook, will it come

with a color profile for the LCD panel that is very accurate?

 

What I'm going for here is - yes it's cool to do your own

calibration, but the whole business seems very strange in the age of

digital. The only analog things that are in the pipeline have very

consistent and well-known characteristics, so any calibration should

be done by professionals with professional gear once and for all.

 

Are there technical reasons this is not happening?

[William Kahn]

Your assumption seems to be that all digital is equal. Not so. LCD monitors have a variety of settings, most of which are not compatible with the world of photography, film or digital. Video cards use a generic profile, based on their assumption that not everone out there is editing photos. Printer makers provide profiles which (hopefully) enhance the printing of photo images. The trick is to get all these guys on the same page, so that WYS on the monitor is WYG on the print. It takes some work, but it ain't rocket science, and it's well worth the minimal effort involved.

[Uhooru]

Its not about being cool, its about being able to predict results and share results in 2 major ways. One, you want the photo on your screen to match the print coming out of your printer..obvious right? Save's time and money. Two, when you send a photo to someone else to print or send a digital file for someone else to view, such as an editor or graphic designer who's going to utilize your image, you want to know that what you see on your screen, they will also see on theirs. Every monitor whether CRT or LCD changes over time, and faster than you may think. Yes the ink is consistant, and the paper profiles are too, but even there, each printer can deviate from the norm. I don't have a special target for my printer. The papers I use are pretty well profiled and I'm getting more than sufficiant results. But the monitor I do calibrate.

 

What calibrating the monitor does using a calibrating device, if I understand it, is optically compare the red green and blue channels and the black/white grey scale against industry based standards based on the color tempeture you choose to use on your monitor. Some like D50, others like 6500K, at school they use 6000K. (Digressing, this obviously creates problems if you're sending your stuff to a place using a different tempeture. But then you have to ascertain and calibrate for that, its not hard) But for everyone using the same temp. as you are it means when you say Red, there is agreement as to what Red is or Green etc. If properly calibrated and the same color temp. A color print will look the same on an Apple ACD and a Nec CRT, given the resolution differences etc. But bascially the colors will match very well. Does that help explain why? For instance I tune mine up for what we use at school, so when a class mate comes over to my place with his powerbook, we can share images on our computers and they look pretty darn the same. That won't happen if you don't calibrate the monitors, unless its blind luck.

[andrew_rodney1]

Displays are NOT stable devices; they change over time. The same LCD made on the same

day from the same manufacturer may not match any other. Then you have the graphic

systems which affect color and you have the (crude at least for LCD) controls for adjusting

them. In actuality, you only have control over the backlight intensity of the CCFL. So there

are all kinds of reasons why you need to calibrate a display. What aimpoint?s are you

calibrating to? That can differ based on a lot of factors. Even the ambient light around a

display can affect your color perception (it?s why we calibrate the white point luminance).

The white point can be many colors (white IS a color).

 

t/

[dmitry_a]

William, yes you're pointing at various places where things can get screwed up.

 

But: say I walk into the store and there's a laptop there on the shelf. I pick it up, open it and it powers up. There's an OS pre-installed and there are no controls except for brightness on a laptop screen.

 

Why the heck do I need to calibrate it? It's a well-known setup that just came from the factory, and if it works nobody's going to tinker with any of the settings you mention. I should be able to just install Photoshop, download printer profiles and start printing. Everything should "just work" in this case.

[Uhooru]

Dimitry, the question has been answered several times. If you just want to play and cruise the net etc. and it looks good to you than fine, you don't have to calibrate it. If you want to have any control over working with images and printing, and not have to trial and error every print because the bloody printing output doesn't match the monitor than it will be much easier, and you'll get much better results from calibrating. You know just visually adjusting contrast and hue if your monitor allows it is "calibration" its not a magic term. You can eyeball it and go your happy way. But the type of calibration we're talking about is really creating a unified color work flow from scanner to monitor to printer to get predictable accurate results when it counts. Hope this helps.

[Ed_Ingold]

1) True, the monitor is (can be) connected with a digital cable. While this avoids losses which occur in the traditional analog VGA cable and connectors, there is still an analog conversion in the screen itself. The lamp and possibly the LCD screen itself ages. Predictable? What happens when you touch the screen? Besides manufacturing variations, most LCD's have various adjustments which are unscaled. From personal experience, my desktop LCD, a Viewsonic VP191 was unusable as an editing screen before calibration - too dark and punchy. Calibration brought it into a highly useful state. The calibration profile (graphed by Gretag-MacBeth) is surprisingly linear, yet not reproducible with the monitor controls alone.

 

2)Epson inks and paper are remarkably consistent, but there are significant differences between papers. A certain degree of calibration is burned into firmware for some printers - notably the 4800 and larger models. That aside, Epson publishes profiles for high-end printers, including the 2200 and 2400, which are very good. Results from customized profiles are only slightly better than the published versions.

 

Other printers are not so consistent. My Kodak 1400 performs much better with calibration than with the bonehead procedure included with the printer. My color laser printer is the least consistent - changing with each lot of paper and change of toner cartridge (there are 4), imaging roll or fuser. Now the color is almost as good as the 1400, but still grainy.

 

3) Apple LCD's, even in their laptops never need adjusting or calibration! OK I said it. Now can I have my children back?

 

Ha! Laptop LCD's are still analog devices and still age - even the esteemed Apple products. Laptop LCD's furthermore have a much more restricted viewing angle, low luminosity, low contrast and are sensitive to pressure, compared to desktop versions. Apple does have color management built into the operating system, so there is much more agreement between programs. I'm a PC person, and find that Gretag-MacBeth handles color management in XP Pro very well, and in a global fashion.

 

Gretag-MacBeth recommends that a touch-up calibration be performed on CRT's every two weeks and LCD's once a month or so. It only takes a minute or two, and is fully automated.

[andrew_rodney1]

-->Why the heck do I need to calibrate it? It's a well-known setup that just came from the

factory

 

Even if we agree that each is identical (and I wouldn?t agree to that <g>), whatever the

behavior, it?s undefined.

 

Some provide a generic ICC profile for the description. And if you want to go that route,

OK. But years and years of experience among those who want predictable color on their

computers have proven that generic profiles range from OK to just useless. Again, a

profile simply defines device behavior. If the two agree, you?re all set. If not, how far are

the two?

 

When you walk into a TV store and see two dozen sets all producing different color but all

getting the same signal, what does that tell you?

[ilkka_nissila]

As people have said, most of these devices are not made for photography. As such the color, contrast and brightness is what it happens to be, and these characteristics will drift over time. While digital stuff doesn't drift, the digital part ends where actual ink is put on paper, when paper is made, when screens wear as they're used etc. How images appear change even as you change the illumination of the room.