What readily available items can be used for color correction or reference?

Question

Are there any easily available things I can carry with me, that I probably have already, that I could use as a rough color reference card while taking photos with a phone?

I realize that most phones will heavily process the images themselves, but if I needed to have a way to reference a specific color, it would be helpful if I had something in my pocket that I could add to the photo. For instance, would a clean US $1 bill be useful as a green reference? What else could I add to this to get other colors?

I realize that I could just get a pocket sized color reference card, but that is outside the scope of my current project.

Answer 1

Apparently, PTFE white matte thread seal tape wrapped around a white polymer eraser works well as a white balance reference. See DIY: Reliable and Cheap Universal White Balance Reference Device.

Answer 2

Likely the Kodak Q-13 Color and grayscale guide will do this trick. Google this and you will see what it looks like. That being said, for your purpose, why not make a reference card using construction paper and school paste. You don't need a calibrated card because you will have the one you made to use as a reference. The Q-13 has been in service for years and years. Their are others, just Google this stuff.

Answer 3

Hum... Let's take the first step.

The most important color reference is white... or should I say gray.

You need to set up your white balance for the light illuminating your scene. You could use a white sheet of paper... but they come in many flavors. Recycled one, super bright, etc. Choose one that has a god whiteness value. The closer to 100 the better one. If it is above 100 it is probably a "fake" white.

But beyond that, no. You are fooling yourself using standard objects. The only reference that they will provide is for that color. A new green bill will be a good reference for a green bill.

Color reference cards are using standardized values so the calibration software assumes what those values should be, so they can correct them using standardized corrections on standardized points on the curves and channels...

Using common objects could be used only for optical corrections, but I would not do that.

Answer 4

You can pick up some paint color samples the next time you are in the paint section at your local hardware store. The samples are designed to match specific paints in different lighting environments, and close examination reveals that they are pure colors, not dithered halftones.

If you forget to bring them with you, you can pick up another set. Even if you can't get the same brand of paint, you will have the original color swatches for comparison.

If you just want a card to set white balance, you try different shades of "white" until you find one that works well with your camera. The cards often have reference numbers that you can use to locate the same colors in the future.

See Using an uncoated Pantone Swatch Booklet as a Color Reference for photos/video?