RGB Color Model |
The standard color model used on the Internet is RGB,
which consists of a set of three values from 0 (zero) to 255 in decimal
notation, or 0 - ff in hexadecimal (frequently mis-spelt as
'hexidecimal') notation.
One of these values is for
red, one is for
green, and one is for
blue - thus:
#RRGGBB
where
RR,
GG,
BB
are the hexadecimal digits specifying the
Red,
Green, and
Blue values of the color.
The colors you create depend on the mixture of these three colors,
which are indicated by their respective numerical values.
Zero indicates the absence of a particular color;
255 indicates the strongest use of a color.
For example,
- RED is: 255 0 0
in decimal, or #ff0000 in hexadecimal.
- GREEN is: 0 255 0
in decimal, or #00ff00 in hexadecimal.
- BLUE is: 0 0 255
in decimal, or #0000ff in hexadecimal.
Colors can also be specified by name, including the
16 widely understood color names:
aqua, black, blue, gray, fuchsia, green, lime, maroon, navy, olive, purple, red, silver, teal, white, yellow.
These colors were originally picked as being the standard 16 colors
supported with the Windows VGA palette.
Color names and
sRGB
values
| | Black = "#000000" |
| Green = "#008000" |
| | Silver = "#C0C0C0" |
| Lime = "#00FF00" |
| | Gray = "#808080" |
| Olive = "#808000" |
| | White = "#FFFFFF" |
| Yellow = "#FFFF00" |
| | Maroon = "#800000" |
| Navy = "#000080" |
| | Red = "#FF0000" |
| Blue = "#0000FF" |
| | Purple = "#800080" |
| Teal = "#008080" |
| | Fuchsia = "#FF00FF" |
| Aqua = "#00FFFF" |
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Setting Page Attributes:
Changing a Background Color |
Once you determine the hexadecimal value for the color you want,
you must enter the hexadecimal value into your HTML.
For example, to change your background color to magenta,
immediately inside your beginning
BODY tag type:
BGCOLOR="#ff00ff"
<BODY Background = "/Images/margin.gif"
bgcolor = "#ffffff"
text = "#000000"
link = "blue"
vlink = "purple"
alink = "red"
>
Notes:
- the hexadecimal color values are preceded by a pound sign (#);
- there are no spaces between the three RGB hexadecimal values;
- the pound sign and hexadecimal color values are situated within double-quotes.
- The Background attribute specfies the URL
of an image to be tiled across the document window before anything else
is rendered.
- The TEXT
attribute is used to control the color of all the normal
text in the document.
This basically consists of all text that is not specially
colored to indicate a link.
The format of TEXT is the same as that of BGCOLOR.
- VLINK (typically blue) stands for visited link, and
- ALINK (typically purple) stands for active link.
Again the format for these attributes is the same as that
for BGCOLOR and TEXT.
- BGCOLOR: this attribute allows the user to specify a solid
background color.
If a background file specified in the
Background attribute cannot be
found, the color specified by the BGCOLOR tag will be used.
This BGCOLOR will also be used if the user has auto load images off.
This BGCOLOR will also be used as a table border color
on Netscape for Windows.
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Color Palettes |
GIF images include color palettes, or predefined sets of as many as
256 colors, which define which colors they will use.
There are two types of palettes --
an adaptive palette, using the colors already in the image,
or a system palette, using a computer platform's preset group
of 256 colors.
Adaptive palettes usually give the best results when the image is
viewed on a monitor that has thousands or millions of colors.
Netscape navigator (and many other application programs) has a
pre-defined set of colors, or color table
that it uses to display images in HTML pages.
If a color used in an image is not found in the color table,
the software will either substitute a color from the color table
which is similar to the color specified in the image,
or it will dither the colors to approximate the desired color.
A color which is "dithered" will appear to be made up of pixels of
two colors, which blend together visually to approximate the desired
color.
Here is a simple Perl script to generate the
the 6x6x6 color map.
HTML Bag of Trix
Quadzilla Archive - Here are some general Tips and Tricks I
even use as a reference daily.
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