AW: what RGB is blue?

Tiemo Hollmann TB toolbook at kestner.de
Fri Jul 1 06:41:20 EDT 2011


Thank you Mark, for your profound advice.
It sounds just as what I was looking for. I will give it a try
Thanks
Tiemo

> -----Ursprüngliche Nachricht-----
> Von: use-livecode-bounces at lists.runrev.com [mailto:use-livecode-
> bounces at lists.runrev.com] Im Auftrag von Mark Schonewille
> Gesendet: Freitag, 1. Juli 2011 11:53
> An: How to use LiveCode
> Betreff: Re: what RGB is blue?
> 
> Tiemo,
> 
> The distance between any colour (1) and a colour chosen by you (2; e.g.
r=0,
> g=0, b=255) can be calculated as
> 
> sqrt((r1-r2)^2+(g1-g2)^2+(b1-b2)^2) <= T
> 
> where T is a threshold between 0 and 442 set by you. Change the colour of
the
> background pixel whenever the distance between the colour of that pixel
and
> your selected colour is less than the threshold.
> 
> I use this technique in Color Converter http://www.color-converter.com
> 
> --
> Best regards,
> 
> Mark Schonewille
> 
> Economy-x-Talk Consulting and Software Engineering
> Homepage: http://economy-x-talk.com
> Twitter: http://twitter.com/xtalkprogrammer
> KvK: 50277553
> 
> New: Download the Installer Maker Plugin 1.6 for LiveCode here
> http://qery.us/ce
> 
> On 1 jul 2011, at 11:39, Tiemo Hollmann TB wrote:
> 
> > Hello,
> >
> > I am taking the mousecolor at different points from an image by script
(not
> > by clicking). I would like to analyse if the color I've taken is a "kind
of
> > blue", or another color. I want to change the backgroundcolor of an
image.
> > The background is always blue, but different blues and changing over the
> > background. So what I want to do is to verify, what is background and
what
> > is foreground of my image.
> >
> > 100% pure blue would be 0,0,255. But for a human being 25,75,130
(greyblue)
> > is also still blue, but 240,20,180 is pink, though the third RGB value
is
> > higher as in my greyblue.
> >
> > So I can't just check only the third RGB value, neither the sum or cross
> > total. Has anybody ever heard, if you can define at all by math "what is
> > blue"?
> >
> > Any color specialist around here?
> >
> > Tiemo
> >
> 
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