Device Link Profiles

Color profiling software also can generate device link profiles.

A device link is a type of International Color Consortium profile that contains two profiles inside of one. In order to create a device link profile, you select the two profiles, along with settings, and then save these ‘linked’ profiles as a device link profile. A device Link profile always contains a source color space and a destination color space, and the conversions always move from the source color space to the destination color space, saving time in file preparation and processing. They are most useful to people who repeatedly use the same specific configuration.

Why might device link profiles be required?

One example is when a scanner application does not embed the source profile in the document containing the image it creates. Storing the scanner’s profile eliminates the need to request the appropriate source profile each time the user wants to print with a configuration involving that scanner.

Perhaps a user also may want to see how a scanned image looks when printed using a specific printer, or may want to look at many images captured on the same scanner at different times before printing the final image.

Since the same devices are involved each time, the graphics application displays a list of device link profiles that the user had previously created for various configurations, allowing the user to select the appropriate device link profile for the current activity.

Another reason to use device link profiles has to do with maintaining channels in color conversions. Typical ICC color conversions require all of the colors in the file being converted — including the black channel. device link color conversions allow the user to maintain the K channel so that the color conversion can happen without any changes to the K channel — such as converting K type to CMYK type. This can be important when making color conversions for certain types of inkjet proofing where you need to maintain the black channel.

It is even more important for making color conversions during plate generation. When used during ripping or plate generation, the black channel must be maintained and device links are a must. In this scenario the device link is used to make the press simulate another printing condition, or to match a printing condition such as GRACoL. Not every platesetter RIP can use device link profiles, but many can, and for those with RIPs that can’t, there are third party applications that can provide these conversions.

Device links are a required component in conversions between different printing conditions, e.g. from offset to gravure. Black channel conversion is achieved with exacting results. Whether single black or rich black output is specified, the device link will manage the requirement.

Currently device link profiles can’t be embedded or assigned in applications like Photoshop because they contain mathematical information for a color conversion rather than describing a color space. Because of this, device link profiles are more complicated and less flexible than traditional ICC profiles and are classified by the ICC as a special type of profile.

A few other points about device links:

• only one rendering intent is available, that which was selected at the time the link was created. 
• links cannot be embedded into images 
• the rendering intent encapsulated in the link is selected in the 'default intent' field in the profile's header. 
• a profile sequence tag in link profiles documents the profiles used to create the profile. 

If you are looking to create your own device link profiles, I personally like the iPublishPro 2 software from XRite.

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