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(S-4A) Experimenting with Colors


The Sun

S-2.Solar Layers

S-3.The Magnetic Sun

S-3A. Interplanetary
        Magnetic Fields

S-4. Colors of Sunlight

S-4A.Color Expts.

S-5.Waves & Photons

Optional: Quantum Physics

Q1.Quantum Physics

Q2. Atoms   (and 6 more)

S-6.The X-ray Sun

S-7.The Sun's Energy
Here is your opportunity to demonstrate the three-color theory by using your computer. I am indebted for this to Joe Burns, on whose color demonstration file it is based. Joe's "Primer" web-course HTML Goodies and his subsequent book by the same title taught me practically everything I know about writing web documents, and both are highly recommended.

You see below two tables with colored fields. The top one approximates the rainbow colors--at least on my monitor (yours may be designed and/or adjusted differenly). The one on the bottom is for you to experiment with. To use this file, use your web browser to look at its "Page Source" (on View menu in "Netscape"). and copy that file to your computer, in text format (you may have to cut and paste --depends on your set-up).

red orange yellow green
blue indigo violet white

Table for trying out your combinations

one two three four
five six seven eight

If you look at the source-code file, you will find it is written in HTML, the language-code of the web. You can however proceed even if you are not familiar with HTML, as long as you only change the entries described below. On your saved file you will see the specifications of two tables. The contents of each cell of the table are preceded by the letters TD (Table Data), and each of the three rows is preceded by TR (Table Row).

The entry which specifies the color of a given cell in the table is of the form


The particular specification above is taken from the bottom cell, whose color matches the background colors of "From Stargazers to Starships." It is actually a combination of three numbers:

D0     FB     FF

What? They do not look like three numbers? That is because they are written in base 16, a close cousin to the binary system (base 2) in which computer hardware is programmed. In that system, instead of counting

0 1 2 3 4 5 6 7 8 9  10   11 12  13  14  15  16
we count
0 1 2 3 4 5 6 7 8 9   A  B  C  D E   F  10

The letters A to F are now numerals. In base 10, 100 = 10x10. The number written 100 in base 16 would in base 10 be written 16x16 =256, and the number preceding it is FF=255. D0FBFF gives the intensity of the three colors which make up the background: D0 is the intensity of red, FB is the intensity of green and the second FF is the intensity of blue, the maximum blue you can get. If you wanted to specify pure red, green or blue, you would choose FF000, 00FF00 or 0000FF, and these choices are in fact used in the first table. Also, 000000 is black--no color at all, and FFFFFF is white, the sum of all three colors at saturation intensity. In between you can have 777777 or AAAAAA or CCCCCC giving you various shades of gray.

If you want to experiment with colors, let your browser read the copy of this file from your computer. The menu-commands depend on the browser, e.g. ("Open ... page source... Save"). Leave the colors of the first table for reference, but change those of the second table using your word processor (always save as TEXT!), then command "reload" and see what you have accomplished. You can also change the color of the lettering, by modifying the color specification that follows the word "FONT"--but don't be surprised to see bizarre results!

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Author and Curator:   Dr. David P. Stern
     Mail to Dr.Stern:   stargaze("at" symbol)phy6.org .

Last updated: 9-23-2004
Re-formatted 26 March 2006

Above is background material for archival reference only.

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