Photo Gray Cards, Color balance your camera and photos

This is not written for photographers but rather for artists.

This article is about getting accurate colors in the photos you take and prints you make using a neutral gray card. Taking photos in rooms with different lights and color temperatures causes errors in color balance of prints. How to take quality photos of your paintings using a gray card is covered in my article. How to Photograph your Paintings – Step by Step from Click to print Giclée

What is a Gray Card? It is a reference card with a specific neutral color that cameras and photo software use to color correct photos.

Do I need a Gray Card? Yes! If you want control of the color in your photos so you have accurate images to post or print. The standard color is “18% gray”. The cards come in many sizes and materials. Your local photo shop and on-line will sell them for about $10. Also called Neutral Gray Card. I have cut an 8″x10″ card into 16 pieces. Now I have little cards that I keep with all my cameras and near my paintings and have given away.

Golden makes an acrylic paint called Golden Neutral Gray paint N6.  I have not tried this paint yet. It would be nice to paint this on the surface on which I photograph my artwork. Maybe some on my easels. I’ll let you know, or let me know if you have compared this. Or https://www.goldenpaints.com/ please send me a tube or tub and I will review it ($15).

Should I use a gray card for every shot? No. This is not necessary for outdoor scenery or landscape photography (in natural light). It is not critical if you are taking posed or candid photos of people or things only as reference for your painting. We often desaturate, turn to black & white, reference photos so not to be distracted by colors and to better see values.

Why and when to use a Gray Card: You want to use a gray card so the colors in your photo are as close as possible to your subject. Have you ever noticed that the President’s podium is gray??? All the cameras in the room use this gray podium to color correct for the lights!

Things that can affect the color in your photo.
If you take a photo with natural light you would expect to have accurate color. That is not always the case.

This article is divided in to three sections,
– Using gray cards to photograph artwork in controlled lighting; mostly using the camera’s Custom White Balance settings.
– Taking pictures of subjects in changing light; mostly using Auto White Balance settings
including notes of caution.
–  Processing your photos is covered in another of my articles about Photographing your Paintings.

Photographing in fixed and controlled lighting.
In this first part I will expand a bit more on how to use a gray card and how to calibrate your camera in a controlled setting.
First you need to have lighting that won’t change based on time of day. This lighting should be bright and as close to daylight as possible (5600K is a measure of color temperature and is found on newer light bulbs). If using multiple lights they should all be the same color unless you want a specific effect.

Read your owner’s manual or do an internet search on your camera’s make and model or your cell phone to see exactly how to set your camera’s color balance. Cell phones, especially iPhones have these adjustments built in.

Cameras with the capability of setting a Custom White Balance CWB:
With fixed lighting set, flash or studio, place your 8”x10” Gray Card where the subject will be. Zoom in or move in on the gray card and take a photo of just the card full frame. You will set that image in your camera as the Custom White Balance Photo (cameras differ on how to do this). In your camera’s menu set the White balance to use CWB. Now every shot in that light will be color correct and you shouldn’t need to correct it with software later.

Taking photos of your art with a calibrated camera. Include this gray reference card or a piece of it, next to each painting or 3D object when it is photographed. It is placed off to the edge of the photo for possible use when processing. If you are taking portraits of a person, have the gray card in the first test photos. Keep one of those test photos to use the gray card reference to color correct your final images.

If your camera can not set Custom White Balance, that’s ok. Still include the gray card in your photo and you can use some photo editing software to correct any color imbalance. Or ask someone with Photoshop to help you.

NOTE: Take this from experience… It might be necessary to stick a little something on the camera reminding you that your camera is NOT set to AWB. Otherwise your vacation photo’s colors will be messed up!!!

Taking photos with changing lighting: Portraits, weddings, grads, etc. Images that printing is the final outcome.

Auto White Balance AWB. Cameras are very good at predicting color balance. Taking photos in AWB is very safe if you will be changing light sources. However AWB can be fooled. What if you have two different types of light sources in your room, or the color of your painting is mostly red. These things can confuse the Auto White Balance of your camera.

– For more control in AWB take a test photo of the gray card or your subject (or your helper) holding the card in each scene where there is different light. You can use the first lighting test shots as a reference to correct the rest of the photos when you get home.

NOTE: When in Auto White Balance the camera will still tweak the color if it thinks is needs to. Like if everyone is dressed in blue. Keep the gray card or a piece of it handy.

There are settings like shade, incandescent or florescent lighting, etc.. WARNING: If you forget to change these settings back to AWB and go from florescent lights to outdoor light, your color will be wrong…. SO USE THESE SETTINGS WITH CAUTION when in changing light!!! Experience talking again…When you are so smart to use those settings, but in a hurry, mistakes will happen! You often can’t go back to take those shots again… AWB is safe and use that little gray card in your pocket…

Side tip. I often take photos of my work in progress with an old point and shoot camera. When I do I will put a little gray card in each shot so no matter what light I am in I can accurately adjust the color balance in Photoshop. I like these photos for my classes as examples.

For more information on steps to process your photos for print or publication see my article on How to Photograph your Paintings – Step by Step from Click to print Giclée

Good Luck,
Bill

 

Last edited 26 Aug 20, Major changes and combined 3 different articles, 10 Apr 19, added this last bit on color monitors and prints from labs. 2 Apr 17, Added more on making copies of original images