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Managing Color in RGB-CMYK Conversions

(May 2008) posted on Fri May 02, 2008

Find out how image-file preparation and color-space conversion can affect color control in prepress and digital print production.


By Rick Mandel

Attaching the profile to the graphics file, then sending it to the printing company may be of benefit, but what is attached to the graphics file? For example, the profile may describe the device that printed the proof that the printing company is required to match. The attached profile may only be the description of the monitor characteristics, which may be helpful to view the graphics file in the settings that your client used. Monitor (or soft) proofing is performed with this method. Generally, profiles do not alter the original file; instead, profiles assist the color-management process for the next step of digital printing—at least, this is the client’s goal when attaching a profile.

 

Client influence

Now, let’s turn the tables to illustrate how our clients affect color management and color-space conversion. The client designs a graphic in a software program, proofs internally, then sends the file to the printing company. The customer may send the file as-is or as a native file converted to CMYK, flattened, or with a profile attached. Looks like a slippery slope with a multitude of variables built in! Ultimately, our job as printers is to match the proof that our clients have approved, which the industry defines as expectation or quality.

Some printers may prefer pro-duction files be delivered in RGB with ICC profiles attached, as this allows the printer to use color-management methods when converting to CMYK. Other printers may prefer files in CMYK mode, as this is the mode required for the printing process. If an RGB file is submitted, it must ultimately be converted to CMYK for print. When the conversion takes place, color shifts can and will occur; therefore, the printer may not want the responsibility to be the one that converts to CMYK.

Attached profiles do have their pitfalls for the digital printer. Fortunately, embedded profiles can be accepted or turned off. A dialogue box usually asks the operator to allow the attached profile to remain. The correct response depends on the how the printing company utilizes color management. The printer’s RIP may be set up to discard any attached profile and use its own profile instead, or the RIP may be arranged to allow the attached profile to impose its will on the printer. Neither scenario creates a predictable response for the device.


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