Capture to Output – Colour Communication (Part Two)
By David Crowther
In the last issue we looked the first three steps of Capture to Output. This covered RAW digital capture, RAW processing to RGB and RGB Editing – Conversion. With the latter two steps, a calibrated monitor is of vital importance. Accurate visual assessment of the RAW capture and subsequent RGB image editing requires implementation of good colour management. We all have ideas of how the captured image should appear, but without following the fundamentals of colour management; we will have no idea if the previews on the monitor are an accurate representation of the colour we wish to output onto paper, canvas, etc.
Editing by numbers alone is possible but can be frustrating. Productivity, confidence and ease of use are just a few of the benefits gained when you start to edit images using both numbers and colour accurate previews. A colour accurate preview on your monitor requires an output profile of the device you wish to simulate. So how can we achieve predictable colour output to our printer that has the colour appearance from the preview on the monitor? The solution to obtain this colour communication is to use ICC profiles.
Output ICC profiles can be built and created by oneself, using a Spectrophotometer and profile building software. Most photographers I work with prefer to use generic output ICC profiles available from a media supplier (Fine Art & Photographic media) or printer supplier/manufacturer (e.g. Canon, Epson, HP). Generic output profiles made by yours truly for the DES range of Chroma Jet and Innova Art media are available from the DES website (http://www.des-pl.com.au/resources/). These profiles have been created with ease of use in mind.
The following explanation for using these profiles is the same procedure used by the major print engine manufacturers, other media suppliers and learned colour experts from around the globe. I am sticking to colour managed output using PhotoShop CS2, which could be argued as being the most common method of doing photographic or fine art prints to a wide format printer. I have used snap shots from Mac (OSX) and Win XP to show that the settings are the same, regardless of your choice of platform.
Commence by selecting the Print with Preview command, which allows PhotoShop to colour manage and print your output. In this dialog you need to select More Options to expand the selections available for colour management. Select Color Management from the pull down (Win XP) or pop up menu (Mac). What should be noted here that this Print with Preview dialog is an element of PhotoShop and not related to any particular print driver.
A color accurate preview on your monitor
The important parts to focus on are the Print and Options areas of the dialog. Of the two radio buttons within Print, select Document. In brackets next to Document is the name of the profile embedded in the image you are about to print. Please make sure to pay close attention to the profile name here, as it should reflect the colour space you are working with. For example, Adobe RGB (1998), sRGB.
Underneath the Document radio button is the Proof radio button. This allows for the printer to simulate another printing device, such as an offset press. To keep it short and simple, we will not discuss this option here.
In the Options area, close attention should be paid to the selections made for each of the following: Color Handling, Printer Profile and Rendering Intent. For Color Handling, select Let Photoshop Determine Colors. This allows for an ICC transform using PhotoShop based on the output profile selected from the Pinter Profile pop-up/pull down menu. The Printer Profile you select should reflect your printer make and model, media type and ink set. The latter is usually reserved for the choice of a matt or photo black ink. This choice is usually dictated depending whether you are using a fine art paper (matt based) or photographic type media. I am often asked as to what is the correct rendering intent to use. There is no right or wrong answer here as one needs to take into account the image itself, the embedded profile, the printer and ink set being used, the paper type and your own preference for the output image feel, look and rendition. Importantly, you should have already decided on the rendering intent by utilizing PhotoShop’s soft proof functionality through View – Proof Setup – Custom.
With the Options all set, click on Print. Having chosen Let Photoshop Determine Colors, we lastly need to be mindful of the actual print driver settings. As PhotoShop is carrying out the ICC colour transform, colour management within the print driver should be set to OFF. As with most generic print profiles, we should also use the correct Media/Paper type setting, Print Quality/Resolution setting and dithering option as recommended by the print profile supplier. These settings are vital as they were the settings used by the print profile builder and are necessary to obtain a colour accurate and predictable result.
I have tried to include as much detail as possible for you, but as usual this forum does not allow us to delve right down into wherefores and whys. As an instructor, I ensure that the finer points and details are always covered in Chromaticity Australia’s Digital Print Makers Master Class.
It may seem like much is needed to produce consistent, colour accurate output on wide format inkjet, but like most things, practice makes perfect, and great results are definitely achievable. Keep in mind that most print drivers today allow you to save frequently used settings for easy recall and selection.
Now that we have covered the fundamentals of Capture to Output, in the upcoming issues of DR, I hope to further explore the impact of colour on our lives and how this affects you, the image professional.
David Crowther is the manager of Chromaticity Australia.
Chromaticity Australia offer colour management training and consulting.
David writes a regular Workshop page for Digital Reproduction magazine.