What is needed to see color?

1. A source of light (like a lamp or the Sun).
2. Something to be seen (like a flower or a star).
3. A detector (our eyes, or a camera film).

• direct source like the Sun or a lamp
• indirect source, like the sky
• self-illuminating source, like "neon" lights

• an object, like a tree, that we see because light is reflected off it and into the detector.
• an object, like a tree, seen through sunglasses, that we see with our eyes, but only in certain colors that the sunglasses let through.
• an object, like fluorescent paints, that actually absorbs light, then re-emits it in its own color (which means it is both a reflector and a source).

A Surprise about "black and white"!

Light that is emitted from a lamp or a star and looks white, is really the combination of all colors in that light. There is really no "white" color and no "black" color! Emitted light looks "white" when the source emits all colors. We conventionally think of color as six major hues - red, orange, yellow, green, blue, and violet. These words you are reading, look "black" because the light in this computer screen is shining three beams of separate colors, which together, make light look white, but in the places where these letters appear, no light is shining. You are really looking at holes in the light!

What about light that is reflected from an object? Unlike the lamp or the star, the object isn't the source of the light, but rather, reflects the light that shines on it from some source. That light is a little different, when it comes to the story of "black and white". Since all the colors are falling on the object, the "black" is seen where all the colors are absorbed and "white" is seen where all the colors are reflected.

The Big Surprise!!!

Objects that reflect light have no color of their own! The color we see from them is the color of light that they reflect. The light that shines on a tree from the Sun is sort of yellowish-white, but the tree leaves look green because, out of that yellowish-white light, the green light is reflected, and all the other colors are absorbed.

Ready for another surprise?

Some objects emit light. Some objects absorb and reflect light. But remember, light is a kind of electro-magnetic radiation. In fact, emitting objects can emit many kinds of EMR, and likewise, reflecting objects can absorb and reflect many kinds of EMR. Now let me tell you about EMR.