Profiling your scanner with the Eye One

A package of software to go with the Eye One Spectrophotometer

The Eye One spectrophotometer from GretagMacbeth is a sophisticated measuring device that can measure detailed spectral information from emissive sources (ambient light or a CRT/LCD display) or reflective sources (print samples or just about any coloured object)

Different kit options enable different functionalities in the supplied software.

Scanner Profiling

This review covers the scanner profiling capabilities that you can activate in the Eye One Match software (you can purchase an activation code).

This feature is not active in the Eye One Design package that Keith reviews elsewhere.

That review covers monitor calibration with the Eye One spectrophotometer, basic printer profiling and measurement of ambient light with the Eye One Share package.

There is a separate review of the Camera Profiling option in the Eye One Photo SG package.

GretagMacbeth provide a range of colour management hardware and software aimed at professional users.

Details of the full range of Eye One solutions are available on the main GretagMacbeth site. [Now X-rite]

Profiling your scanner

If you are completely new to colour management I'd suggest you might also like to have a look over my Introduction to colour management article on this site. However, I have added links, in this review, to articles and information on this site and others explaining some of the concepts mentioned here.

There are two basic types of scanner. One measures reflected light from an object (typically a flat print or document) and the other measures transmitted light (typically film or slides). I'll be covering profiling two flat bed scanners later, so I'll concentrate on scanning pictures.

To get an accurate scan, both the characteristics of the light source and the sensor that is being used to capture it need to be considered.

Think first of the light source, ideally it should provide illumination that provides a similar range of colours to the light that you would view the subject.

Think of using something like a yellow street lamp bulb and you will see why not all light sources are useful. There are some examples in the Eye One review.

Secondly, there is the sensor that is recording the reflected light. Our eyes capture colour information by being sensitive to three main colours of light (Red, Green and Blue).

It's actually quite a bit more complex than just three colours, and characterising our colour vision is a specialised field (Spectral response of the eye and more detailed biology of colour vision) Various optical sensors will have their own characteristics, which may be tailored with the addition of coloured filters.

If you add in the need to have an economical and long lasting light source, and a high resolution sensor to designing a scanner, then you arrive at a number of different basic designs (HowStuffWorks-Scanners, - scanner light sources)

The upshot of all this is that despite the best efforts of the scanner manufacturers, the representation of colours and brightness (luminance) of your scanned picture may not relate very well to what the picture looks like to you.

One way of addressing this problem is by 'profiling' the scanner. You take a known picture, scan it, and compare what the scanner gives you to what you should get. The resulting profile is in effect a 'translation' document for use to convert from 'what is recorded' to 'what it should be'

The whole question of input device profiling can become a tricky one when you consider that any colour will produce some sort of output from the scanner, so the concept of a scanner 'gamut' is not a meaningful one in the same way as a printer gamut, which is limited by the inks and paper to a certain range of colours. If you think this makes it tricky for profiling scanners, at least they have a constant light source -- unlike your camera. I'll be covering some aspects of camera profiling in a future article.

The scanner driver software, whether a Photoshop plug-in or a full stand alone application may well have numerous correction and adjustment features which you should be aware of, since any profile you build is only relevant to particular scanning conditions.

If you can find a manufacturers profile for your scanner, then do try it, they can make quite a difference, but without profiling the scanner yourself, how can you know whether it's accurate, or just 'looks good'?

Profiling

An 8"x11" printed target is supplied by GretagMacbeth for profiling reflective scanners. This is a patchwork of 288 colours which cover a range of colours at different brightnesses. The Eye One Match software makes use of a 'Target file' which contains spectral information on each coloured patch. Note that this is much more than simple RGB values, it gives the brightness of each patch in 10nm bands across the whole visible spectrum. This allows the profile generation software to allow for different types of lighting and sensors.

If you have not done so before, you will need to create a target file by scanning the test target with your Eye One spectrophotometer. If you are using another target (such as an IT8 film target), then you select it here.

First you need to calibrate the unit with the white patch in the base.

Once you have created the target file, it will be available for profile generation without going through this step.

As with all colour management reference tools, you should keep the target print in it's envelope in a safe place away from light and damp or any other environmental factors that may affect the print (ozone from older laser printers is particularly good at fading prints)

Now you have a target file we can see how your scanner's version of the target differs from what the Eye one 'saw'. You need to get a scan of the target with your scanner and save it as a tiff file. This is loaded into Eye One Match.

You need to rotate and crop the scanned image to get just the coloured patches.

There is one final check to see that the measured chart and the scanned chart are the same one. You can see from the picture that the scanned chart is darker, but it is the same chart (and the right way up)

The profile is then created and saved (do remember to give it a meaningful name)

Remember that just like monitors, scanner profiles will change over time as the lamp ages, it also helps to have the scanner switched on for a while before profiling, so that everything gets to warm up properly.

How well do the profiles work?

If you want to profile a transmissive (film) scanner then you will need to get a special target. My own Canon FS4000 is used rarely these days since I moved to a fully digital workflow, and when it is used, is mainly for black and white. So I decided to test two flatbed scanners I have in the office:

A UMAX PowerLook III - this has a transparency adapter, SCSI interface and is attached to an old Mac running OS8.6
An Epson Perfection 1200U - USB flatbed connected to G5 Powermac - OSX

The UMAX may be old, but it is still a very useful scanner :-)

I created two scans (with all corrections turned off in the scanner software) and went through the profile generating process above. Do remember to make a note of all the scanner settings for when you want to use the profiles for real work, since the profile is dependant on the settings being the same.

The picture below shows the original scan from the UMAX, if you move your mouse pointer over it you will see the original Epson 1200U scan. If you then click on the image (and hold the button down) you will see the scanned image after opening a raw scan tiff file in Photoshop and assigning the appropriate scanner profile.

You should be aware that if you take an untagged (i.e. no embedded icc profile) scan and open it up in Photoshop, it will look different dependant on how you colour manage it. You should assign it the scanner profile and then convert it to your working profile if need be. There are some examples of how this affects web images in the article on web colour management.

Just in case you were wondering how big a range of colours the scanner has captured to make the profiles, I used the Mac OS X ColorSync Utility to compare some colour spaces...

	The Epson 1200U scanner colour space (grey outline shape) compared with the sRGB space. Apart from a small area near the base, the sRGB space is entirely within the scanner space. The coloured line represents pure spectral colours
	Same comparison, but this time with the larger Adobe98 colour space. Notice that the overlap is complex, i.e. there are some colours in A98 that couldn't be captured, and some in the scanner space that can't be represented in A98. Of course the scanner will give an output for any colour, so it's not technically correct to describe the 'gamut' of an input device. Think of it more as the range of colours that are accurately mapped - outside of the space they may be correct, but they may not be
	This comparison is with the Epson 1290 printer using Premium Glossy Photo Paper. Even though the print space is much smaller than the scanner space, there are still a few colours that can be printed but not necessarily accurately captured. The 1290 with PGP paper produces very good quality prints. I have one myself that produces better glossy prints than my RIP driven Epson 9600. However print lifetime with the glossy dye inks is nowhere near what you could get from the Ultrachrome pigment inks.

May 2010 X-Rite annouce new profiling software for Q4 2010

i1 Match and ProfileMaker Pro will be superseded by i1Profiler later in 2010. We have some notes and press info in the X-rite information section of the Northlight blog. For purchases after April 1st 2010 here will be free upgrades, along with other offers when the software is available.

Sept. 2008 X-Rite and the current i1 range

It now consists of two options. The functionality is the same as we have reviewed, but exactly what you get varies. As a result of this rationalisation, the i1Photo, i1Photo SG, i1Proof and i1XT have all been discontinued, and the i1 range now consists of:

The i1Basic - i1Pro measuring device with monitor profiling software
The new i1XTreme - professional monitor, RGB and CMYK printer, camera, scanner and projector profiling, plus profile editing

With the i1XTreme you can calibrate and profile:

Monitors - LCD, CRT and laptops
RGB output devices
CMYK output devices
Scanners
Digital projectors
Digital cameras*

Summary

Simple and elegant solution to getting accurate scans from your scanner.

The software is easy to use and the required steps are clearly set out.

You probably won't profile your scanners very often but the way the software steps you through the process makes it much more likely you will remember how it works.

The final quality of the scan is limited by the quality of the scanner, but a profile will help you get the best out of it.

Eye One packages are available from a wide variety of suppliers

The unit tested came from Colour Confidence in the UK.

It is available for Macs and Windows PCs.

More Info

An Introduction to colour management article by Keith and collection of CM info.
The Viewing page - basic monitor set-up
The Eye One design - monitor calibration/profiling, light measurement and basic print profiling.
Colour management links on this site
Colour Management Check-up kit review
The PrintFIX - Basic printer profiling
Printer profiling with the Eye One Photo - review
More advanced printer profiling with the Eye One.
The Spyder2 Pro - Monitor calibration and profiling
The Eye One Display 2 - Monitor calibration and profiling
More general scanning information on this site
http://www.hamrick.com/
The software Keith uses to scan film - includes scanner profiling features (requires target)
http://www.targets.coloraid.de/
Scanner targets (film and reflective)
Review of the Camera Profiling option in the Eye One Photo SG package.

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