Color perception with different light sources

By: Oliver Mews

Colors can look different depending on the spectral composition of the light source under which a color or object is viewed. For example, a bright red car viewed in the artificial light of a gas station or streetlamp will look very different when viewed in daylight. The same principle applies to color assessment in photography. If no standard light box is available one still judges a picture best under cloudy skies during daylight.

Sample representation of color temperatures: An image with daylight lighting (6500K), fluorescent, and incandescent lighting.

The reason for such color differences has to do with the spectral composition of the viewing light and the different light reflection and absorption properties of the object viewed. Even two supposedly “same colored” objects, such as two pieces of fabric, may appear identical under artificial light, but vary when viewed under daylight or another light source (a phenomenon known as metamerism).

Light sources have a whole range of spectral compositions and, as a result, different color characteristics.

To put it simply: if a light source lacks a certain color range in its spectral composition or if this range is proportionally weaker, the illuminated object can only reflect its colors with these limitations.

When it comes to visual imagery in photography, different light sources can “bend” colors quite a bit. You can find individual colors in an image that appear completely different from their original capture, while also finding colors that appear identical even under different light sources. In order to compensate for these possible color differences in the best possible way, an ACTUAL color standard must first be determined.

Light sources have a whole range of spectral compositions and, as a result, different color characteristics.

Spyder Checkr ensures color balance

If the colors of the photographs are beyond the camera-typical deviations, this is normally due to the color spectrum of the light source.

A harmonious color balance can be achieved with the right color correction. Spyder Checkr24 or Spyder Checkr can help you with this.

Spyder Checkr makes it possible to determine the ACTUAL state of the occurring color differences in order to compensate for this later during editing with the help of software.

This is done quite simply with a test image of a reference color chart, such as the Spyder Checkr. If this test shot is opened in the corresponding software, it can compare the recorded colors with the actual reference colors in a few moments and thus make a correction via the HSL color control. This color setting is then saved for the RAW converter as a user-defined setting. This way, all images photographed in the same light can be reliably color-balanced and corrected with a single click.

In the same way, the color reproduction of two or more different cameras can also be matched. All you have to do is photograph the Spyder Checkr with each one of your cameras in their respective light and create the appropriate color settings within the software.

What is the color rendering index?

The general color rendering index, Ra or CRI for short, is an order of magnitude between 0 and 100, that reflects the quality of the color rendering of an artificial light source compared to daylight.

Examples of Ra values

Here are some examples of the quality of color rendering using the color rendering index (“Ra”) of different light sources compared to daylight, where 100 stands for the greatest or best possible color rendering: