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Color Facts


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Color Facts-

In case you would like to get more of a feel for the color and resolution aspects of your computer, here is a brief resume of the subject - simplified as much as possible, but hopefully giving you some idea - if you were previously unaware of this aspect of the subject.

Your monitor -

We are fortunate nowadays that the era of monochrome monitors is all but gone - and we probably take our color monitors for granted. We will now just delve superficially into color and, a little about resolution, so that you may have a better grasp of what it is all about ............................

Your monitor and image software works by using the "additive color model" - -

Look at the image below - where the three primary colors of Red, Blue and Green overlap, they "add" to give three new colors (the "subtractives"). All other colors in between can be formed by appropriate mixes of the basic three. These points are also dealt with on the Color Models page.

Your Printer -

Your printer on the other hand, works somewhat in reverse to this and usually is based on the CMYK (subtractive) model - here we have the three subtractive colors - cyan, magenta and yellow, which when mixed take us back to the additive primary colors of red, green and blue. The "K" is actually a separate black because the mix of these subtractive colors does not give a full and satisfactory black unaided.

When one or more of three primary color phosphor dots on your monitor screen is raised in energy level, by a beam of electrons, light is emitted, appearing as a final color that is a result of three color dot's "energy mix".

Your image files are all made up in a similar manner by being constructed of "Pixels" or dots (see for more on this below), each containing a mix of the primaries.

The size and number of these pixels in an image determines how good the resolution is, or how "sharp" and well colored it looks. When we "compress" an image, some of this color range and also edge definition can be lost - giving a less clear picture.

The RGB Model, details -

This "RGB" color model nowadays generally has 256 levels of color for each primary - thus an RGB value can range (in decimal, base 10) from R 0,G 0,B 0 which is black, to R 255,G 255,B 255, which is white. All color combinations occur between these two extremes. 256 (decimal) happens to be 8 "bits" of information, which in binary (base 2) ranges from zero (00000000) to 255 (11111111), or in hexadecimal (base 16) from 00 to FF.

Without going into too much detail on binary and hex (see the Binary & Hex' page for more information) - let it suffice to say that with 8 bits of information per color, we therefore have 256 x 256 x 256 possible permutations for our RGB model. That is often referred to as "16 million colors", or, 24 bit color -- 8(bit) x 8(bit) x 8(bit).

("32-bit color" is for all practical perposes just 24-bit color that is aligned so that the color information for each pixel in the bitmap starts every four bytes vs. every three bytes. The only reason this is done is that on the Intel 32-bit PCI/AGP/Memory data bus its more efficient to get at data that is "32-bit aligned". [with 24-bit data you often actually have to read the pixel's data twice--and then mask for the bits you are interested in] the "fourth byte" is generally wasted.)

Most of us now, with modern monitors and graphics cards, are fortunate enough to have this level of color capability, or better - but, some machines are working just with a simple total range of 256 colors (8 bit), (often still found on old notebooks and laptops) - this requires that a process called "dithering" has to be used to try and "fake" the intermediate colors. If you have ever seen this, it is unsightly and results in a poor approximation, with lots of dots showing. This is why we try to use the so called "web safe" color palette in web design - to try and "target" the main colors in the limited 256 color palette of some machines.

The "Web Safe" Palette -

If we take colors in
decimal increments of 51 (within the 0 to 255 range available) , then we have a spread for each primary color of 0,51, 102, 153, 204, and 255, yielding a total of 6 x 6 x 6 color combinations = 216. In hexadecimal, this equates to increments of 33 (within the hex' range of "00 to FF"), so that for any given color we progress through the range - 00, 33, 66, 99, CC, FF. Again, 6 x 6 x 6 = 216.

This look at binary and hex is all rather unimportant if all you want is to build a web site! It is however an attempt to just touch on the nuances of the subject to give you some idea of the rationale behind the use of "Web Safe" colors, all still of importance too when using .GIF images at times (an insurance to try and make sure what you see is what you get!). Many books are available on the subject should you wish to learn more.

Not vital info for most but yet again, like much I have included- presented for those who might find it edifying.

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