Light and Color

Using Light

As was true with photos, getting the lighting correct is very important for graphics that look good.  However, unlike photos where we had to work with the light that the camera had, where the best we could do was improve it, here we have complete control of how the lighting affects the image.  However, with all that control means that we need to plan ahead and determine what lighting we want, whereas in photos we could just look at what we were given and figure out how to make it as good as it could be. 

Here's an example of an open cardboard box, without any lighting applied.

And here is that same box, with lighting applied to it.

Its easy to see the difference!  In this case, the author imagined the source of the light to be above and a little to the left of the box.   So you can see the shadow coming down from it and to the right.  Also the right-front face of the box is darker than the left-front face of the box, because some light is on the left-front face, coming a bit from the left side, whereas the right-front face is in the shadow.  Also, the inside of the box is in shadow because the walls are limiting how much light can get in. 
If you look closely you may figure out that there is no way the box could physically be lit like this, the angles of lighting simply aren't possible, but that's not important.  What is important is that there is some aspect of lighting, and that gives the eye enough to separate out the different surfaces, unlike in the first picture.  In graphics, unlike photos, it isn't necessary to make the lighting super realistic, the audience isn't expecting that from graphics, but there still needs to be enough to be pleasing to the eye.

Using Color

When the human eye sees color, it is actually recording electronic waves of light hitting cells in the back of the eye.  A single particle of light is called a photon, and each photon oscillates at a specific frequency, which corresponds to a wavelength.  Photons with a faster frequency (and shorter wavelength), are towards the violet end of the spectrum, while photons with a lower frequency (and longer wavelength) are towards the red end of the spectrum. 
Below is a graphic depicting the spectrum of visible light.
You may notice that the two ends are dark, these are actually not black, rather they glow just as brightly as all the areas in the middle, but in the infra-red and ultra-violet colors that the human eye cannot detect. 

The colors above are the only colors that the human eye can detect.  You may notice that there are many colors missing: brown, purple, not to mention white, black, and gray.  This is because these colors (and many more) don't actually exist, but we perceive them because of how the photons of light hit our eye.  To learn more about the visible spectrum of light, see this page:

When we see an area that is black, that is because very few or even no photons are hitting our eye from that direction.  On the other hand, when we see the an area that is the color white, we are getting a lot of photons, from every single color hitting our eye at the same time.  Gray is simply in between that, when we see a medium number (too many = white, too few = black) of photons, from all the different colors of light, we will see gray.  All the other colors are found by having photons at two or more different frequencies hit the same part of the eye at the same time.  For instance, if we have two photons of red for every one photon of green (and no other colors), then we will see brown in that area.  If we see one photon of red and one of blue, we will see purple. 

So, brightness of  the color is determined by the total number of photons, and what color we see is determined by what frequency or combinations of frequencies the photons have when they strike our eye.

As we learned in the photo section, when a computer monitor projects light out to our eyes, it is projecting Red, Green and Blue.  These colors can be added together to make all the other colors.  However, when we print an image out onto a piece of paper, the paper isn't projecting light into our eyes like a computer screen is, rather it is reflecting the light in the room.  When we were projecting light, we started with black, and added colors to get the color we wanted...if we wanted to get to white, then we added all the colors.  However, when we talk about reflecting light, we start with a white light, then we start taking away parts of that white light, by absorbing the photons of certain colors, so that only the color we want is still being reflected.  If we absorb all the light and don't reflect any, then we are left with black.  For this reason, printers use the colors Cyan, Magenta, and Yellow for their printing.  Cyan will absorb Red, Magenta will absorb Green, and Yellow will absorb Blue. 
For more on reflected or "subtractive" color, see:íntesis_sustractiva_de_color

As you can see in the images of the box, in the previous section on lighting, the changes in lighting affected the color of the image, and it is important that the colors you use match with the lighting that you are applying to your image.  However, more general color choices also will affect your image.  If you are attempting to create a representation of something real, like a box or a forest, then you need to make your colors close to those of what would be realistic for those objects.  On the other hand, sometimes you are making graphics that don't correspond to something in real life.  For instance, in a logo for a company or the color of text in a banner.  In this case, you need to choose color combinations that work well together and don't clash. 

Unfortunately, colors that do and do not work well together vary by culture.  Colors that go well together in the United States won't work well together in Africa.  The same way, colors that clash in India might work well together in Peru.  To see a quick example of this, look at a sample of flags from different countries.  Each country picks a flag with colors that work well together in that country, but I'm sure you can see some that do and don't look like they belong together in your culture!




That's just the countries that start with A, B, and C and there's already a whole ton of different color combinations.  We could go on for a very long time (which we don't have) on the theories of what colors are good together and which are bad.  Indeed many artists will have to take several classes that revolve around this.  Just keep in mind that there are colors that go well together, and look for them as you create graphics.  It also might be a good idea to ask someone for their opinion of which colors they think will go well together in your graphic.