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10-24-2006, 08:27 PM

I have a tutorial how to convert rgb to hsl. Could anyone write it in Javascript for me?


1. Convert the RBG values to the range 0-1
Example: from the video colors page, colorbar red has R=83%, B=7%, G=7%, or in this scale, R=.83, B=.07, G=.07

2. Find min and max values of R, B, G
In the example, maxcolor = .83, mincolor=.07

3. L = (maxcolor + mincolor)/2
For the example, L = (.83+.07)/2 = .45

4. If the max and min colors are the same (ie the color is some kind of grey), S is defined to be 0, and H is undefined but in programs usually written as 0

5. Otherwise, test L.
If L < 0.5, S=(maxcolor-mincolor)/(maxcolor+mincolor)
If L >=0.5, S=(maxcolor-mincolor)/(2.0-maxcolor-mincolor)
For the example, L=0.45 so S=(.83-.07)/(.83+.07) = .84

6. If R=maxcolor, H = (G-B)/(maxcolor-mincolor)
If G=maxcolor, H = 2.0 + (B-R)/(maxcolor-mincolor)
If B=maxcolor, H = 4.0 + (R-G)/(maxcolor-mincolor)
For the example, R=maxcolor so H = (.07-.07)/(.83-.07) = 0

7. To use the scaling shown in the video color page, convert L and S back to percentages, and H into an angle in degrees (ie scale it from 0-360). From the computation in step 6, H will range from 0-6. RGB space is a cube, and HSL space is a double hexacone, where L is the principal diagonal of the RGB cube. Thus corners of the RGB cube; red, yellow, green, cyan, blue, and magenta, become the vertices of the HSL hexagon. Then the value 0-6 for H tells you which section of the hexgon you are in. H is most commonly given as in degrees, so to convert
H = H*60.0
If H is negative, add 360 to complete the conversion.


Philip M
10-24-2006, 08:52 PM
Sorry, we are not here to do your homework for you. See the rules:-

1.5) No homework assignments - Do not post your entire homework assignment and request that other members do it for you. This is considered cheating, and your thread may even be used by your school to prove your guilt. Now, you may ask for advice or help on a specific aspect of your assignment that you're having trouble with. Use common sense as far as what's acceptable in terms of soliciting help with homework assignments.

10-24-2006, 10:03 PM
You need to change your major from programming to management...

10-27-2006, 10:35 PM

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