What do you really know about light?

Do you know how much light affects the color of objects?

March 3rd, 2017 | OPTIS group

News couleur 1


Materials and colors can't be seen by the eye. It actually detects the light and objects' colors totally depend on the environment where they are located. 

Just look at a landscape at sunset to realize that the colors of a scene stand out differentley than when the sun is at the zenith. And for good reason! The eye is an organ generally conceived to see under natural light: that is to say under clear blue sky. On the other hand, the sunlight does not send the same amount of light for each of the colors: this balance between colors is called "spectrum" 



As soon as they pass into artificial lighting, colors are modified: the spectrum emitted by the source is not the same as that of the sun and depends directly on the nature of the body that radiates. In fact, objects are no longer perceived the same way. This is especially why you could be surprised at the color of a garment once worn out of the fitting room. 


This is all more true today with the multiplication of LED lights whether they are colored - which will immediatly change the color of the object - or white. For the latter in fact, white is obtained either by direct association of three RGB colors, which provide the white color as a screen does. More commonly, fluorescence is also used and adds yellow to a dominant blue spectrum. 



A yellow lemon, for example, absorbs blue and diffuses all the other colors of the light it receives. So, if you light up this one with red light, you'll get a red lemon. On the contrary, under blue light, the lemon will appear black. Be careful then! Greengrocers could sell you a yellow lemon instead of a lime, simply using green lights in their store! Try the experience and light up a lemon with a blue LED: this will make it easier to understand the influence of the light/color combination. Then repeat the same experiment under a white LED - your  phone for example - and finally compare with the outside light. 




               We experienced by simulating the interior of an airplane, just for you! Surprising, insn't it? 




As we have just seen, the color of an object mainly depends on its environment. To determine the color of an object we usually rely on its color in the sun. However, a question subsists: If you can not know the color of an object, how to characterize it? In fact, the color of an object results from the absorption of colors in the latter. Some colors will be returned and others will not. In the case of yellow lemon, the yellow color is returned while the blue does not return to the observer. Blue is absorbed. When the operation is repeated for several colors, some will be absorbed and others will be returned. It is the quantity of light absorbed according to the color that is called spectral absorption and which will intrinsically characterize the color. 


RGB graphics software - although enable to implement physics based algorithms - isn't precise enough to accurately represent a color as they will only consider the three RGB (Red, Blue, Green) components of the colors. 


OPTIS makes it possible to simulate the spectral radiation of the source which will illuminate the colored object. Depending on its color, the object will return only part of the light and it's this light/object combination that results in the final color of the product. It's precisely this phenomenon that we reproduce in our solutions, and the reason why we can say that the results you get with our software are "physically correct". OPTIS software is actually the only approach to date that guarantee the ultra-realistic color of an object.