Color Management - 2

The Printer

So now, as the first part of color management, you've got an accurate monitor but you find the prints don't look like the image on the screen.
There are several reasons for this.

• The monitor works in red, green and blue, the primary colours, which make up white light when mixed together. Unfortunately, it is not possible to print successfully with red, green and blue inks. This is nothing to do with photography or computers nor is it is the fault of Epson or Hewlett Packard; it's always been the case.

• Offset and inkjet printers alike use cyan, magenta and yellow with a separate black to help the mixture along.
• A monitor will display thousands and often millions of colours.
  CMYK inks cannot produce anything like this number.
• A green on the screen will be produced with a mixture of cyan and yellow and it might look fine.
• A blue will be produced from cyan and magenta and it probably won't look much good.
• A monitor, like a transparency, is lit from behind and has a vibrancy.
• Printing is on paper and uses reflected light which takes away much of this vibrancy.
• The characteristics and tone of the paper also affect the final colour.

We know the monitor uses an RGB colour space while a printer uses a CMYK colour space. This means the large range of colour on the RGB display has to be squeezed into the CMYK colour space, which can only reproduce a much smaller range or gamut of colours.

To bridge the gap between the monitor and a specific printer with its own inks and paper, very accurate settings need to be put into the system.
This is the job of the profile.

• A printer profile is made for a particular printer, one type of paper and one set of inks.
• Once you've decided on a certain fine art paper and suitable inks, the profile will work well on that combination.
• Change the inks or the paper and the results won't be the same; you'll need a new profile.
• There are numerous suppliers of this profiling service and they will supply the image file made up of many small colour patches.
• This file is printed out and the patches are then measured by a spectrophotometer, which reads the LAB colour values on the print.
• These values are compared with the RGB values of the master print. The colours are compared via the LAB colour space and the results are entered into the colour settings to bring the colours produced by your printer in line with the master print.
• These settings make up the printer profile which is put into the system.
• Finally your prints will look like your monitor display.

Most people will be better off using a specialist service.
There are some recommended websites at the bottom of the page.


Profiles are installed in ......

Mac OS10 - User / UserAccountName / Library / ColorSync / Profiles

Windows 2000, XP, ME - WinNT(back slash)System32(back slash)Spool(back slash)Drivers(back slash)Color

Printing

• In Color Handling, in order to use a printer profile, choose Let Photoshop Deteremine Colors.

• In Printer Profile, choose the custom profile, if there is one.

This example has chosen the profile called Smooth Fine Art, referring to a paper type.

The image is colour managed by the printer driver.

• If there is no unique profile, choose sRGB IEC61966.
This is the narrower colour space used by desktop printers.

• With Same as Source, the image data is not changed.
Choose this if printing a target print or if the image is already converted to the printer's space.

Also under Options is a suspicious looking item called Rendering Intent.

Rendering Intents

The four rendering intents are set by the International Color Consortium (ICC), and all color management systems use them. Gamut is the range of colours a device can cope with.

Perceptual Rendering
The gamut of the source file is compressed into the target space (the print).
It does this by desaturating colour until they fit into the print's gamut.
Smooth gradients and the relationships between the colours are maintained and the overall look of the image can be good.

Saturation Rendering
This is best for strong graphic primary colours such as bar charts. Colours can shift as they are made to fit into a new gamut but with this sort of subject matter that is not usually critical.
Saturated colours in the original space will still be fully saturated in the target space, although hue and lightness can suffer.

Relative Colorimetric Rendering
This intent does a white point conversion, which means it adjusts the white of the source to the white of the output and shifts other colours with it.
It also clips out-of-gamut colurs to the next hue that can be reproduced.
There can still be some sudden gaps and sharp changes.
Often it can retain more of the original colours than Perceptual.

Absolute Colorimetric Rendering
This reproduces colours exactly, with out-of-gamut colours appearing as near as possible for hue and saturation.
When looking at a white, the eye with considerable help from the brain, is very adaptable and a range of shades will be interpreted as white. This flexibility influences how other colours are seen.

Absolute colorimetric rendering will try to reproduce the original white in the target space, which means it will have some colour. With truly white paper around an image, the image will have a cast.
The second problem with this intent is that we see colours next to and compared with others and that is how we judge them. If some of these colours are changed (the out-of-gamut colours), the relationship with the in-gamut colours change and the result can look strange.
This intent is best for proofing devices with much larger gamuts and should be ignored for normal use.

Note

• A digital camera should have its individual profile rather than relying on what is already in the camera. The better systems will include the necessary hardware and software to undertake this.
• If scanning, a scanner should have its own custom profile.
• The image has its profile, which translate the numbers in the image file into colours.
• The monitor has its profile, and with this Photoshop creates a display of that image.
• The printer has a profile, which tells Photoshop what colours it can print, and which numbers it needs in order to print these colours.

Summary of procedure

2. Decide what printer, paper and ink combination is to be used.

3. Printers are set up to work best on the maker's papers and inks. e.g. glossy paper is printed with the Inkjet film paper setting. Third party papers and inks don't necessarily work this way; a matt paper might print better on the glossy setting. It's all to do with the coating rather than the paper surface.

The printer's best neutral position must be found before profiling.
Go to Edit > Color Settings > Color Management Policies. For RGB select Off.
Go to File > Print. Under Print Space > Profile choose Same As Source.
Under Advanced Settings, choose No Color Adjustment.

4. Print a greyscale on all the different paper settings under Print > Media Type. Choose the printing resolution you will finally want to use, such as 1400dpi.The idea of this test is to get the optimum printer settings for that combination of paper and ink, prior to a bespoke profile.
Decide which paper setting gives the best result so far.

6. The profile is installed into the computer and it translates the colours from one device (the monitor) to another device (the printer) to produce the 'perfect' print.


The workflow is as follows:

1. Monitor
2. Calibrated with monitor device
3. To produce a calibrated monitor
4. Profiling colour patches are printed
5. Referenced against LAB colour space
6. Printing profile is produced and installed
7. The printer prints via the profile to produce prints which match the monitor image.

Cameras and Scanners also need to be profiled.
They suffer from the same minor discrepancies as monitors and printers.



After reading about colour management in these tutorials, you'll probably realize how essential it is to successful work in Photoshop or any digital imaging programme. Greater understanding of the process will come when it is put into practice. Here are some useful color management resources:

Neil Barstow Consulting

• Good articles on calibration and profiling.
• Articles on choosing printers and unblocking printers, but not the clearest of sites to work through.
• Calibration equipment sold.
• Color management services include calibrating, profiling and training.
• Profiles aren't the cheapest but you get the best.
• Your monitor and prints will look reborn.

More Information

• Profile makers for displays, scanners, cameras and printers.
• Good range of calibrating equipment for sale.
• Good range of profiling software for sale.
• Quality monitors and spectrophotometers.
• Training and consultancy services, online and offline.

More Information

• Everything necessary for monitor calibration and profiling.
• A extensive shop with selected monitors, colour management equipment, printers, books, inks and papers.
• A good range of Greyscales and Colour Charts for accurate white balancing.
• Natural light lamps for accurate viewing of prints.
• Consultancy services and training courses.

More Information

• Profiles for printers created.
• A clear and easy-to-follow website.
• Efficient service.
• Good profiles at a modest price.

More Information

• InCamera software is for creating custom ICC profiles for digital cameras and scanners.
• Fast and simple, using industry standard colour charts.
• The system will work with GretagMacbeth, HutchColor or IT8 charts.
• The chart is scanned or photographed;
  colour data is compared to the known colour values of the charts;
  ICC profile is created;
  the profile is put into the system and it integrates with the color management workflow.
• The dynamic range and colour balance of the greyscale is corrected along with every colour across the spectrum.
• The results from scanner and camera are more predictable and colour is more reliable.

More Information

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