You specify a color by specifying a number that represents the color. You can specify the number explicitly or by using an expression that includes the RGB (r, g, b) function.
For the numbers and expressions that specify common colors, see Table 10-2.
The formula for combining color values into a number is:
red + 256*green + 256*256*blue
where the amount of each primary color (red, green, and blue) is specified as a value from 0 to 255.
The RGB function calculates the number from the amounts of red, green, and blue specified.
To create cyan, you use blue and green, but no red. If you wanted to create the most saturated (bright) cyan, you would use maximum amounts of blue and green in the formula, which is indicated by the number 255 for each. The following statements show the calculation:
red + 256*green + 256*256*blue
0 + 256*255 + 256*256*255
0 + 65280 + 16711680
16776960
The following expression specifies the brightest cyan:
RGB (0,255,255)
Notice that the expression specifies the maximum for green
and blue (255) and 0 for red. The expression returns the value 16776960.
To specify cyan, entering the expression RGB(0, 255, 255)
is the same as entering the number 16776960.
Table 10-2 shows the numbers and expressions to enter for some common colors. The number and expression for a color are equivalent. You can use either.
Color |
Expression to enter |
Number to enter |
How the number is calculated |
|---|---|---|---|
Black |
RGB (0, 0, 0) |
0 |
0 (no color) |
Blue |
RGB (0, 0, 255) |
16711680 |
256*256*255 (blue only) |
Cyan |
RGB (0, 255, 255) |
16776960 |
256*255 + 256*256*255 (green and blue) |
Dark Green |
RGB (0, 128, 0) |
32768 |
256*128 (green only) |
Green |
RGB (0, 255, 0) |
65280 |
256*255 (green only) |
Light Gray |
RGB (192, 192, 192) |
12632256 |
192 + 256*192 + 256*256*192 (some red, green, and blue in equal amounts) |
Lighter Gray |
RGB (224, 224, 224) |
14737632 |
224 + 256*224 + 256*256*224 (some red, green, and blue in equal amounts) |
Lightest Gray |
RGB (240, 240, 240) |
15790320 |
240 + 256*240 + 256*256*240 (some red, green, and blue in equal amounts) |
Magenta |
RGB (255, 0, 255) |
16711935 |
255 + 256*256*255 (red and blue) |
Red |
RGB (255, 0, 0) |
255 |
255 (red only) |
White |
RGB (255, 255, 255) |
16777215 |
255 + 256*255 + 256*256*255 (red, green, and blue in equal amounts at the maximum of 255) |
Yellow |
RGB (255, 255, 0) |
65535 |
255 + 256*255 (red and green) |
