Big "Picture" Calibration Question

[RegRoy]

I'm confused about the big picture of calibrating my monitor. I understand (thanks to the people on this forum) that to achieve my goal of trying reproduce what I see on the screen on my prints, that calibration needs to be done.

What I don't understand is the calibration workflow.

1. If you create an ICC profile for your monitor, why does a company like mpix need to send you their ICC profile, too?

2. And if you already have an ICC profile for your monitor, why do you need calibration hardware? My 21" LCD has an ICC profile with the drives from the factory. Why is this good/not good?

3. Can calibration hardware be used on multiple machines -- say if I actually learn something and go out and buy a better monitor?

 

[Garbz]

1. ICC profiles only describe the device or file compared to a standard colour space. For instance an image you are working with will have a working profile. AdobeRGB, ProPhotoRGB, or sRGB. sRGB is the standard so any image or device without a profile is automatically assumed to be sRGB. These profiles say the colour sRGB(255,0,0) is this very specific shade of red. Now another profile such as your monitor or printer profile is then used to determine how to display that shade of red. Say your monitor has a wider gamut and photoshop then wants to display that above shade of red. It now uses the monitor's ICC profile to say aha! I need to display MonitorRGB(245,5,3) to correctly render sRGB(255,0,0).

Now the monitor colour space (3 primaries made up of red green and blue) will never match the colour space of a printer which mixes a completely different set of colours. So you can view a picture on your screen in your perfectly colour managed environment but it won't match your print because the printer simply can not produce the right colours. The process of conversion is called soft-proofing and takes the above process a step further by saying: Let's render on the monitor using the Monitor's ICC profile the image how it will look like if we first convert it to the Printer's ICC profile.

It allows us to view the output on one device as it would appear on another device. But in order for this to work we need the ICC profile of both the monitor and the printer.

2. Two reasons. Firstly Monitors drift. You get variations with age, and with temperature. You get variation with backlight brightness. The calibration software that comes with the NEC Spectraview for instance will give an error if any settings at all on the screens are changed since it's last calibration run. Secondly the factory didn't test YOUR screen. It simply tested a sample. Production variations, even things like circuit changes can happen on an identical model screen and will have an effect. One would hope that a change in the backlight would cause the manufacturer to change the model number on the screen, but sometimes this isn't practical and an old item is no longer available.

3. Yes, within bounds of the hardware and licences. So far the only hardware issue I have heard of is that the Spyder 2 will not work well on wide gamut screens and NEC actively don't support this calibrator for this reason. Beyond that any hardware is good. It's just a question of the software. Also the software varies from the Bundled with the hardware "click this one button to do everything" type program, to dedicated software from third parties which supports a multitude of calibrators, custom curves, different settings, and will provide options for calibrating printers, lightboxes and other nonsense. And then some software is included with some more upmarket monitors like NEC SpectraviewII is bundled with an NEC branded i1 Display 2 on all "Spectraview" screens, and will only work with NEC screens but will work with any calibrator. (except Spyder2 )

It's all quite flexible.