Tuesday, September 29, 2015

Improving Color Consistency with the X-Rite ColorChecker Passport

Different cameras see color differently - even within the same brand.  Color accuracy is not just a matter of getting the correct white balance.  Different sensors simply render color differently.  You don't have to take my word for it.  Check out the test below.

Here is a test scene with a color chart (in this case, the X-Rite ColorChecker Passport).  Because many sensors have difficulty rendering red, I also included two red objects that are familiar to many people: a can of Coke and a Netflix envelope.  I used the same exact lighting setup for the shots (a remote Yongnuo YN560III bounced to a white ceiling and triggered by a YN560TX).  I took shots of the test scene using three different cameras -- the Sony a6000, the Olympus Stylus 1, and the Samsung NX500.  I took the shots in raw, then I used the white balance dropper on the black square of the color chart to equalize the white balance.  I also tried to adjust the exposure as closely as possible.

One of the biggest differences is how they render the color red:

In case you're wondering, the top one is from the Stylus 1, the middle is the Sony a6000, and the bottom is the Samsung NX500.  In my opinion, among the three, the Stylus 1 has the most neutral/accurate colors.  The a6000 has reds that are too orange.  The NX500 has reds that are a little deeper.  It's not as accurate as the Stylus 1's red but it's not unpleasant in my opinion.  Is there a way to make the colors more accurate?  Moreover, if you are using more than one camera to cover an event, can the colors be made to look similar between the cameras?

Whether you want to make the color more accurate, or you want more consistency between different cameras, you can benefit from using a color calibration tool.  One such calibration tool is the X-Rite ColorChecker Passport.

With the ColorChecker Passport, you take a photo of a pocket-sized test chart. The Passport software analyzes the test chart photo and automatically creates a custom DNG raw profile for your camera to correct for color inaccuracies.  DNG camera profiles include not only information about color rendering, but also contrast and tone curve for each color channel.

Technically, you should create a custom profile for each camera/lens combination under the same lighting conditions that you will use for your photo.  However, with the X-rite you can do a dual-illuminant profile that can work across a wider range of lighting conditions.

I used Passport to generate custom profiles for the shots above.  I applied the profiles to the shots, and here are the results:

Stylus 1 - calibrated

a6000 - calibrated

NX500 - calibrated
The shots now have more similar colors (although not perfectly identical).  Even looking at each shot individually, there is a huge improvement in the color accuracy of the Sony a6000 so that the red isn't so orange anymore.  The NX500 colors also look more accurate.

The Passport (and its big brothers the ColorChecker Classic, and the Digital SG) isn't the only color calibration tool available.  There's also the SpyderChecker which I will review next time.  The difference is that the X-rite calibrators run within Lightroom (you don't have to launch another software), and they create DNG camera profiles, whereas SpyderChecker creates presets.

If you want to improve the color accuracy of your photos, as well as the color consistency between different cameras, check out the X-rite ColorChecker Passport.