Color Names. All standards-compliant browsers should handle these color names. These color names can be used with the CSS properties of color and background-color :. For other colors, it’s safest to use a numerical representation …. RGB Color.
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All standards-compliant browsers should handle these color names
These color names can be used with the CSS properties of color and background-color:
For other colors, it’s safest to use a numerical representation…
The human retina has three kinds of color-sensitive photoreceptors that were traditionally called red, green and blue cones
Visible colors can be created by adding different amounts of the three primary colors, red, green and blue
Color monitors display colors by adding different amounts of red, green and blue light
RGB color components are usually defined on a scale from 0 to 255
Two ways to specify turquoise using rgb in CSS:
Over 16 million colors can be represented this way!
Numbers in the range 0-255 are represented in base 16, using two “digits” that each have 16 values, drawn from 0..9, A..F
Using hexadecimal colors in CSS:
RGB color for each pixel is stored in 24 bits (3 bytes)
How much memory is needed to store a 300x500 pixel image?
300 x 500 x 3 = 450,000 bytes (450 kB)
2 bits per pixel
24 bits per color
“bits per pixel” is also called the “bit depth”
bit depth must be large enough to store all of the colors
GIF Indexed Color
The GIF file format is an indexed color format that allows 256 colors (out of a possible 16 million colors!)
*There’s also a small amount of fixed overhead for storing file type, dimensions, etc.
Other Image Formats
- millions of colors, compressed, nice for photos, does not allow transparency
- millions of colors, compressed, nice for line art and graphics, allows 8-bit transparency
- limited to 256 colors, nice for line art and graphics, allows 1-bit transparency, supports animation
Generate all formats and compare with Fireworks!
Never use BMP files!