File Basics: Rendering Intent
by Jeff Lazell – September 13th, 2014
Welcome to File Basics, a new feature to the X-Rite blog where I hope to demystify a lot of the settings and terms associated with building an effective post processing workflow. I worked on the production side of the photo industry for almost a decade and I know that focused, succinct explanations are not only the best way to learn, but can sometimes get you out of a sticky situation. Today I would like to focus on rendering intent.
When it is time to prep a file for print, choosing the correct rendering intent can have a huge effect on outcome of your finished print. Unfortunately though, this choice weighs heavy on a lot of our heads because we are unsure what this term means. Furthermore, it can be hard to tell what the actual difference is between the options we are presented with.
Very simply put, selecting a rendering intent is how you tell the program or printer you are working with what to do with all the colors that are considered “out of gamut”. Which is to say all the colors the pixels in your monitor can create, but the ink set you are working with can not. This will of course differ from printer to printer because a printer utilizing twelve ink cartridges can reproduce far more colors than a printer utilizing four.
Here we have our four choices as illustrated by the print dialog box in Adobe Photoshop:
Now, two of these choice’s actually have no use in digital photography. Saturation rendering intent is meant for use with charts and diagrams, where the color’s intensity is important, but not so much the specific hue. Absolute Colormetric is mainly used in applications such as medical imagery where exact replication of only a few colors is extremely important.
So, for our purposes on this photography blog we can eliminate those two from our choices and focus on the other two, Perceptual and Relative Colormetric.
Choosing Relative Colorimetric actually does two things. First it takes all the colors the printer or colorspace can reproduce and does so, exactly. Then, it takes all the ones out of gamut and maps them to their closest in gamut equivalent. This rendering intent has the benefit of causing no over all tone shift to the image, however it can have a downside. Sometimes if a photo contains subtle gradients that range out of gamut, these colors can get mapped to the same in gamut point. The colors then stack upon one another and cause banding, for this reason this rendering intent is most effective in files that have a small amount of out of gamut colors. The banding effect is most common in places like sky tones where the blues range out of gamut and it is a very undesired outcome, so lets look at our other option.
Instead of taking all of the out of gamut colors and mapping them in, perceptual effectively takes all the colors in the image and squeezes them until none are left out of gamut. This avoids the banding issue entirely, however it can cause an over all color shift in the file. Perceptual is usually the choice to make when your photo contains a large amount of out of gamut colors.
The truth is that often the difference between these two can be pretty subtle. Decisions about which one is best should be made on a case by case, photo by photo basis. Luckily with a properly calibrated monitor and printer you can use Photoshop and Lightroom’s soft proofing function to get a very accurate preview before you print. The soft proofing process has been covered in the past by Coloratti John Paul Caponigro (Article Here), but an updated version is forthcoming in another installment of File Basics.
I hope you find this information useful when setting up your own post processing workflow. If you have any questions please post them below. When I get enough questions about one topic I will turn to the answer into an article like this one. I hope that with the help of the readers of this blog I can create a good resource for photographers and production artists.
Learn how you can stop guessing and start knowing with color management solutions from X-Rite at www.xritephoto.com.