If
java disabled or no main menu showing above - use links
below.
|
|
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.
|
|
Back to Top
|
