CHAPTER 9 — Skin Tone Adjustments 1 – Automatic removal of the Infra Red Effect

Abnormal skin tones are immediately recognized as a manifestation of color distortion. Skin tone distortion can result from an unseen portion of the electromagnetic spectrum. When a camera sensor detects energy it generates a voltage response representing that energy. The sensor itself does NOT distinguish color. Today’s sensors are sensitive enough to respond to wavelengths beyond the visual spectrum such as infra red frequencies. When your camera allows infra red light to generate a voltage response the color red will be boosted in the skin tones of the image. Perfectly Clear has a solution.


Today’s camera sensors are sensitive enough to respond to Infra Red Energy

Figure 45A common challenge in digital photography is what we’ll call the over responsiveness of the cameras sensors to a range of long wavelength frequencies unseen by the human eye.

Heat is emitted from people as infra red radiation. Your camera has three color filters which overlay the camera’s sensors: red, green and blue (an exception to this can be Nikon camera’s use of CYM filters and Foveon’s proprietary non-filtered approach). Infra-red light passes through the red filter and therefore generates a voltage response for the “red” sensor. As infra-red is not seen by the human eye this voltage response is effectively boosting the “red” channel. This is a camera limitation that is going to result in color distortion. Because the longer wavelengths of light are most often represented in skin tones, this is where the distortion will occur.

Perfectly Clear will automatically search for and detect excessive red in skin tones and reduce it. In the “after” image note how the skin tones have been reduced but the other reds in the image have been maintained.


Skin and human physiology

The body regulates the rate of heat loss by dilating or constricting blood vessels at the surface of the skin. When our body is hot or is producing excessive heat, as by exercise, exertion or exposure to sunlight, our arteries open up (dilate) and blood comes more to the surface of the skin to release the bodies heat. This accounts for the reddening or flushing of the skin.

A more prevalent reason for “flushing” of a persons’ complexion, and completely unrelated to working out or excessive heat, is dehydration. The human brain is 1/50th of our body mass but receives 25% of the blood flow. The brain is 85% water and when your daily consumption of water is inadequate your brain will demand priority on the water in your system. Dehydration activates the hormone histamine to ration the water in your system. The facial flushing is a result of the brain demanding water. So when you want your skin to fit within the preferred skin tones increase your water (and sea salt) intake! It’ll take 3 months to rehydrate your body. We wish you good health!

Skin tones in your photos will have to be balanced between camera sensors capturing to non-visual light, skin tone preferences of what you may prefer skin to look like, and the reality of the human physiology of the moment recorded in the original image. Perfectly Clear allows you the choice of Real Color and your preference.

Skin Tones and the human eye

Abnormal and improper red skin tones are an unwanted color distortion in your photos. In such a case their effective removal is necessary to reproduce your original experience. The challenge remains that the human eye is a response mechanism recording the actual skin tone color and not that which you might “prefer”. Better matching of the original image in the mind’s eye requires accurate colors for you to achieve the benefits that an accurate photo delivers. Photo Accuracy [link] demands Real Color.