Optical Red

[Allan Rahbek]

Do anybody know what color the Optical Red is ?

Thanks, Allan.

[Julie Deane]

Hi Allen -

What are you referring to? A color mentioned in a book? A color on a computer screen?

The only thing that comes to mind immediately is an optical mix of magenta and yellow - 100% each, which looks like red when put together, one over the other. This is from my old days as a graphic artist in a printing company: for printing we had to mix our four colors of cyan, yellow, magenta and black to get any desired color.

I don't know if this is what you are looking for.

[Allan Rahbek]

Hi Julie.

I know the printing colors, some very strong and clean ones.

But this Optical Red is used for portraits by Adrian Gottlieb who is also a member at SOG. He have a homepage with many interesting informations, besides some excellent portraits.

He explains that he sometimes use the Optical Red. I just wonder if it is some red neon mistake or what.

Allan

[Henry Wienhold]

Hello Allan
I'm not sure , but Adrian Gottlieb may be refering to a final thin transparent glaze of red in order to give flesh color a warm glow and make the figure stand out more. To give the image that outstanding quality that the old masters were able to do so well, but I could be wrong.

[Allan Rahbek]

Henry, this is most likely the explanation.

By glazing with red you will damp down all other colors relatively more than the red, and thereby make it stand out as stronger in tone and lighter. Optical stronger.

I could not understand why he would need any stronger red than the cadmium he use.

Thanks, Allan

[Steven Sweeney]

I have enquired of Adrian about his use of the term and would hope to have his response anon. Patience will likely be rewarded.

[Steven Sweeney]

Adrian provided the following response:

Optical red is a highly subtle and thin halo of red around a light area. The red exists not on the light object, but on the darkness around it. The use of Optical red can be found in the works of most any master, most noticeably in Rembrandt, Caravaggio, Velazquez, and Bouguereau. I prefer to apply it so that you would only notice it if you already knew to look for it. After all, optical red is merely a tool. I don't feel the need to shout, "Hey! Look! Optical red!!"

In short, optical red tricks the eye into seeing a glare, or greater intensity of light. When the sense of light has already been achieved, optical red adds a second punch, causing the light to truly appear as light.

Has this clarified things?

[Allan Rahbek]

Thanks, this was very informative.

If I have understood it right this will be the effect of blinding.

I believe this tool can be seen clearly in the picture "St. Peter Denying Christ" by Rembrandt.

Not only has he used the red in big parts of the shadows, which creates a glowing temperature to the whole painting and especially the lit parts, he also enforced the tonal contrast in shadow areas close to the light-source.

Allan

[Tony Pro]

I used optical red in this painting... note the "red glow" just on the outside of the profile of the forehead... It's a wonderful concept of giving "life" to any portrait or figure...

Remember, light is tangible believe it or not... so when bright warm light reflects of flesh, it can cast a "glow" or "halo" to produce an atmosphere in the painting.

Hope this helps!

Tony

[Chuck Yokota]

So, if optical red creates the illusion of the brightness of the adjacent light area in the minds of the viewers, does that mean it's just a pigment of their imagination?