1.1 Color Perception

To see the color, we need a light source; it could be the daylight, a lamp, or a candle. And without this light source, color will never be percept.

The white daylight of the sun contains all the color spectrum, and the surface exposed to this light will reflect a certain color depending on the exposed object’s nature or pigment.

The eye percepts the reflected eye, and depending on the color temperature and wave length the brain distinguishes that color.

1.2 Color Models

1.2.1 RGB:

RGB stands for Red, Green and Blue. The three colors that create every other tone of color that is visible on your screen. There is no black or white ‘color’. Neither is there yellow or purple. They are all combinations of red, green and blue. White is the sum of all three colors while black is the absence of all three colors.

1.2.2 CMYK:

In four-color process (CMYK) printing, primary colors (Cyan, Magenta, Yellow, and Black) are mixed together to produce most of the colors that you see in normal magazines and color books.

CMYK is what the vast majority of commercial printers do, although there is a wide range of options. Images and artwork targeted for reproduction in a CMYK color space must be properly formulated to print correctly. If you’ve had the misfortune of trying to get an accurate print from an RGB image, you’ve just had a glimpse into the technical realm of 4CP (four color process) printing.

1.2.3 H.S.L.

HSL stands for hue, saturation, lightness, while HSV stands for hue, saturation, value. HSL describes colors as points in a cylinder whose central axis ranges from black at the bottom to white at the top with neutral colors between them, where angle around the axis corresponds to “hue”, distance from the axis corresponds to “saturation”, and distance along the axis corresponds to “lightness”.

This model was first formally described in 1978 by Alvy Ray Smith, though the concept of describing colors by these three dimensions, or equivalents such as hue, chroma, and tint, was introduced much earlier.

1.3 Color Gamut

Color Gamut simply is the range of colors that a certain color model can produce, RGB model which is used in TV screens and computer monitors has a wider gamut than the CMYK model which is used in most printers and commercial offset presses.

When converting from one color model to another, this conversion is passing into a mathematical process, the accuracy of this conversion depends on the software you are using, Adobe Photoshop for example is more accurate than Adobe Illustrator, so always place CMYK files into Adobe Illustrator and Adobe InDesign.

1.4. Visible Spectrum:

The sun produces a wide range of spectrum including Gamma rays, X-rays, Microwaves, radio waves, but our eyes can only percept a limited range of colors, which is called the visible spectrum,

1.5. Color Temperature:

Measuring Color Temperature

Color temperature is measured in degrees Kelvin (k).

Higher color temperatures correspond to cooler, blue light and

Lower temperatures correspond to warmer, red light.

Color Temperature            Similar To

1500 k                                    candlelight

2680 k                                    40 W incandescent lamp

3000 k                                    200 W incandescent lamp

3200 k                                    sunrise and sunset

3400 k                                   tungsten lamp

5000 K                                   xenon lamp/light arc

5500 k                                    electronic photo flash

7500 K                                    overcast sky

10000 up to 12000 k          bright blue sky

1.6. Color Wavelength:

Beside that colors have temperatures also colors have certain wavelengths, so the eye could distinguish them.

Color wavelength is measured in nanometers (nm), the visible spectrum that our eyes can percept starts from 380 nm (blue) up to 780 nm (red), and all other colors are in between these two values.