What is color and how does human vision relate to the camera


Understanding what color is

Color is the first impression we have of objects or places. Even before we interpret shapes and forms, color is influencing our interpretation of whatever it is we are looking at. When the color helps the viewer of a photograph to better understand the object the viewer has a good experience and their understanding is enhanced. As photographers, we can use color to enhance the experience in any way we want, by either reinforcing what we already know, or by calling that foreknowledge into question. And what if we eliminate color? One of my favorite genres of photography is B&W. While I don?t want to get too side tracked as I?ll plan to revisit this topic in the future, but I simply want to say that by removing color the viewer is left to solve other visual problems and that can be good thing. It makes the brain work in ways it doesn?t normally have to work. And the impressions we have regarding shapes, forms and the relationship between objects is done differently with the absence of color. But, this is an article on color, so back on track!

How to talk about color

There are two primary ways to talk about color, a scientific or objective method, and an emotional or subjective method. Understanding both is important to getting good results with using color in our images.

Color drives interpretation, at least in part, of our visual language. Whether through color associations or simply the perceived brightness, or importance of a color, many factors come into play when we are considering color.

How color works, physically

The human visual system is extremely complex, and I don?t pretend to know it all. However, the basics are certainly good for photographers to understand as there are many similarities that can be drawn from our ability to see and how digital cameras work. 

The eye has a light-sensitive coating on the back side called the retina. Cameras have digital sensors. How the eye differs drastically though is the idea of how light is detected. Camera sensors have photosites and each one has a color filter over it so only one color, red, green, or blue, is recorded. The eye has two different types of photosites. They are the rods and cones. Rods are spread out across the majority of the retina and the cones are very concentrated in the fovea area. Rods are for seeing in the dark, you don?t interpret color with rods, only subtle differences of tone or luminance values in dark areas. The cones detect either red, green or blue light and those signals are sent to the brain for understanding the scene before us. This is somewhat similar to the raw processor demosaicing the raw file and making a full-color image out of it. And I also love how the foveon sensor by Sigma is the one sensor that records all three colors at all photosites. It?s not exactly like the human visual system, but it?s a good choice of name none-the-less.

Diving a bit further into the rods and cones. There are about 120 million rods in the eye. And about 6 to 7 million cones and, as stated before, they are concentrated in the fovea area. Actually, there?s a region called the macula which has both rods and cones, but the majority of cones are in the .3mm wide area called the fovea. Step back a bit and think about all that. When you combine both eyes together you have about 14MP of information being put together. To put it another way, 5K screens are almost 15MP in resolution. That?s a lot of information the brain is computing in real-time, and on top if seeing basic shapes we get depth perception too!  Whenever I think of these types of things I just am in awe of these awesome details of creation.


So the fovea is roughly .3mm across. Those cones are packed in with amazing density. Our full-frame sensors are 36mm wide. Granted the common sensors are also between 24 and 45MP in size as well. Too bad we can?t get the sensor down to the size of the fovea,,, oh wait, I almost forgot about cell phone sensors for a bit. JBut even with that you have nothing close to the dynamic range the eye can handle.

Objects and color

When measuring and interpreting things we like to have a standard for which to base these interpretations. Thanks to Sir Isaac Newton who discovered all wavelengths of light are contained in mid-day sunlight, we tend to use that as a standard for light quality. Of that visible spectrum objects will either reflect certain wavelengths of light or absorb them. It all depends on the pigments contained on the object. One fascinating object to photograph is the fall color. Once chlorophyll is no longer the dominant substance in a leaf the color changes and other pigments take over.

Changes in Perception

There are so many things that influence our perception of color. The biggest factor is likely our culture and how we are taught to react to color. The second biggest factor, I would say, is surrounding colors. Color can be heavily or subtly influenced by its neighbors. The amount of influence depends on many factors such as how close the two hues are to each other, the amount of one color vs. another color and even the purity of saturation on the colors involved. As a small exercise, take an object and place it in different areas of the room. Put it on a dark surface, a bright surface, and a neutral or colored surface. Study how the object itself changes, or rather, your perception of it changes, with the different placements. The same happens in your photography as well. Sometimes we have to modify our post-production of certain colored objects, so they are interpreted properly, according to our goals.

Color and Memory, Culture

I?ve touched on this before, and that is the effect our culture has on our understanding of color. We are taught certain meanings and associations with certain colors. Our personal experience can also affect our understanding or opinions on color as well.

Local, Optical, Arbitrary Color: Above I mentioned how we like to have standards for how we interpret or talk about color. The context, as it were. 

Local Color is the most basic of expectations. For example, a scene that is brightly lit at high noon with the colors being interpreted or rendered exactly as we ?expect? them to be. This would be a ?daylight? white balance on your camera.

Optical Color is when you have variances in the actual measurement of the color of an object due to differences in the light source or other factors. That same generic scene mentioned above but with different light, such as during a storm or at sunset, would be an example of an optical color situation. We still understand easily what the subject is, however, the mood may be changed due to the different colors exhibited due to the late evening light.

Arbitrary Color is when you have taken full creative freedom in post-production and make things whatever you want them to be. Have you ever made a green sky? If so, this would be a good example of an arbitrary color choice. As an artist you have full reign on the colors you use, but I would caution you to choose wisely. We don?t want to upset our viewers too much now! J

Perception Curve

Greens and yellows are easier to perceive due to them being the brightest of the colors. Have you ever wondered why there?s twice as many green photosites as there are red or blue on a digital camera?s sensor? The luminance values may play into that. But it?s also interesting to note that of the cones, about 64% are sensitive to red light, 32% are sensitive to green light and between 2?7% are sensitive to blue light. Maybe it has something to do with the actual wavelengths of light? I don?t know.

Meanings of color: RED

Finally, we get to thinking about the meanings of color. In this post I?ll start off with the color red. I think I chose this color because I recently visited Hong Kong and in Chinese culture, red is a color of good luck. Most the taxi cabs are red, and it?s common for brides to wear red on their wedding day. Though each color has different meanings in different cultures, I will be focusing mostly on the norms of western culture, or you could even blame me for focusing on an American interpretation of the color. Undoubtedly colors will have unique meanings in your areas, and I welcome your feedback via my contact form so I can update this post where possible. Additionally, as I talk about other colors, you?ll certainly find some overlap in these associations.

Positive Associations for Red

Love, dynamic, luck, vital, romantic, passion, fun, festive, importance, commanding, alert, complimentary, joyful, visible, hot, compassion, power, courageous and new or late breaking.

Negative Associations for Red

Evil, danger, debt, bureaucracy, war, anarchy, salacious (think ?red-light? district), rebellious.

The Effect of Red Light and Strength

Apparently red light can also have an effect on one?s measured strength. According to a study conducted by researchers at Samford University in 2008, 18 men were tested for muscular power and hand grip strength. The researchers modified the ambient light and measured the muscle strength of the subjects under red, blue and white light. There was a significant increase in measured strength when red lights were used. Blue lights had an increasing calming effect. 

I don?t know what we can specifically do with this information, except to understand that red in an of itself causes some type of psychological change which enhances one?s ability to perform in tests like these. Does it have to do with adrenaline? I?m not sure. I couldn?t find the entire report, just the abstract.

On the Podcast

I?ve turned this topic into a podcast as well! Give it a listen on the Latitude Photography Podcast. I also was able to include a discussion about listener submitted images that exhibit the color red. 


Details of the eye http://www.blueconemonochromacy.org/how-the-eye-functions/

Color in Motion

Color Studies book


Light and strength research