Math Is Fun Forum

metalfred

Guest

Help triplets to 2d conversion formula

Hi all,

I am learning software development and I need to do something that requires some pretty good mathematics I think. I am not very good and been working to solve this problem for a few days now, any help is appreciated.

Here is what I am doing:

I need to find a way to convert pixel colors (rgb) into a 2d xy coordinates.

I know that the perfect red (255, 0, 0) color is at this position:

rx = -26;
ry = -100;

I know that the perfect green (0, 255, 0) color is at this position:

gx = -50
gy = 76

I know that the perfect blue (0, 0, 255) color is at this position:

bx = 62;
by = 10;

I know that white (0, 0, 0) is at this position:

wx = 0;
wy = 0;

I know that black (255, 255, 255) is at this position:

blx = 0;
bly = 0;

Now I need to figure our the formula to convert something like:

(234, 23, 54) to a X Y position.

This is an image of what I am developing, I have something that works right now but the formula is not right.

Vectorscope:

http://www.codeguru.com/forum/attachment.php?attachmentid=24192&stc=1&d=1232848650

Can this be done ? Impossible maybe ?

Thanks alot of the help !!! *pulling hair*

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: Help triplets to 2d conversion formula

The co-ordinates for the colour

are given by

By the way, white should be (255,255,255) and black should be (0,0,0); you got them the wrong way round. Also, your co-ordinates for white (255,255,255) are wrong; they should be

metalfred

Guest

Re: Help triplets to 2d conversion formula

Thanks a lot for the answer JaneFairfax!

If I understand correctly, in a practical way if my pixel is (233, 45, 72):

-26 * 233  = -6058

-50 * 45 = -2250

62 * 72 = 4464

-6058 -2250 +4464 = -3844

-3844 / 255 == -15,07

X == -15,07

-100 * 233 = -23300

76 * 45 = 3420

10 * 72 = 720

-23300 +3420 +720 = -19160

-19160 / 255 == -75,13

Y == -75,13

Am I correct ?

Thank you so much for your time ! I really appreciate.

-fred