Canadian Geographic Photo Club - How does CG ensure colour fidelity when it publishes photos?
  

How does CG ensure colour fidelity when it publishes photos?

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Production manager Mike Elston compares a form that just came off the press to an earlier colour proof. (Photo: Paul Politis Photography)

If you've ever tried printing an image at home, you may have experienced the frustration of discovering the colours in your printed image don't match the vivid colours you see on your computer screen.


Imagine you submitted your photo for publication in a magazine and it wasn't printed the way you thought it would look. You'd probably be enraged.

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Tutorial: Tutorial: Monitor to printer making colours match

DEFINITIONS:
RAW: an uncompressed digital image format containing all the unprocessed data stored in the camera's image file at the moment the photo was taken.

JPEG: a compressed digital image format. The acronym stands for Joint Photographic Experts Group, the international committee of imaging experts that defined the algorithm for JPEG image compression and set this format's standards.

Dpi: dots per inch is a linear measure of pixel density used in digital imaging. The higher the dpi, the better the quality of a printed image.

RGB: the primary colour model used by monitors and other electronic display devices, in which viewable colours are formed by combinations of red, green and blue light.

CYMK: cyan-magenta-yellow-black is the colour model used on four-colour printers and printing presses and hence the one that should be used for images to be published. Combinations of those four colours can produce just about any colour of the rainbow.

Before you grab the phone and call the magazine to complain, stop and think. Is your monitor calibrated? A non-calibrated monitor distorts the colours, meaning that what you see on screen doesn't correspond to the colour information stored in the image file. The image would look quite different on a monitor that is calibrated.


At Canadian Geographic, we're very meticulous about our production process. Here's the scoop:

The current issue of Canadian Geographic is printed on a high-speed web press.
Photo: Paul Politis Photography

At least once a month, we calibrate our monitors to correspond with our colour proofer (a big Epson printer), which in turn is calibrated to correspond with the printing presses at Dollco Printing, the Ottawa company that prints our magazine.


Photographers who shoot with digital cameras send us high-resolution files of their images, either in RAW or JPEG format, because we print at a relatively high resolution of 300 dpi.


The image-processing software we use, Photoshop, is set to indicate whether or not there is a colour profile embedded in the photographer's image file. We use this to ensure consistency between what the photographer saw on his or her monitor and what we see on our screens.


We ask photographers to submit their digital images using the RGB colour model and not CMYK, as we prefer to do the CMYK conversion ourselves to ensure the highest printing standards.

Canadian Geographic is printed on a continuous roll of paper, then sliced into 16-page sections called forms.
Photo: Paul Politis Photography

Depending on the image or group of images from an assignment, and if time allows, we might ask the photographer to send us one or more prints from the shoot which we could use as a colour reference when making any adjustments. This, of course, is not an issue if we are working with transparencies (slides), because they are, by definition, first-generation originals. All we have to do is match the transparency.


We do not edit image content. But if necessary, we'll do minor adjustments to brightness, contrast, sharpness or colour shifts after converting to CMYK.


Once the CMYK image looks as close as possible to the RGB image submitted by the photographer, we print a proof for review.


Once the editors, creative director and production staff have reviewed the page proofs for the whole issue and any necessary changes are made, we're ready to go to press.

Production manager Mike Elston signs his approval.
Photo: Paul Politis Photography

Dollco's web press prints our magazine on huge rolls of paper that get cut down and folded into so-called signatures, or forms, containing 16, eight or four magazine pages.


Canadian Geographic's production manager, Mike Elston, goes to Dollco for each press run to ensure the printed sheets match the colour proofs. If necessary, he'll ask for ink adjustments to be made, which requires changing the density of either the cyan, magenta, yellow or black inks used by the press. This is not the time for major changes. All the work we put into calibrating our monitors and colour proofer ensures any adjustments are minor.


Once Mike is satisfied with the match, he'll sign off and leave until the press staff calls him back again for the next set of pages. Each run of 16-page forms takes about five to six hours, which, unfortunately for Mike, means he often gets called in the middle of the night to approve the next batch of pages being printed.


By Maria-Lucia Castillo

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