Given an RGB value what would be the best way to find the closest match in the database?

Question

I have a rgb value and if it doesn\'t exist in the color table in my database I need to find the closest color. I was thinking of comparing all values and finding the diffe

Answer 1

Let the database do it for you:

select top 1
  c.r,
  c.b,
  c.g
from
  color c
order by
  (square(c.r - @r) + square(c.g - @g) + square(c.b - @b))

Where @r, @g, and @b are the r,g,b values of the color that you're searching for (SQL Server parameter syntax, since you didn't specify a database). Note that this is still going to have to do a table scan since the order by has a function call in it.

Note that the extra square root call isn't actually required since it's a monotonic function. Not that it would probably matter very much, but still.