How can i convert multi color to Black and White ??

[majid.ebru]

HI
How can i convert multi color to Black and White ?

in image down :
 how can i convert blue rang color to black&White rang color ??

thank you

[lainz]

(R+G+B) / 3

Or more nice methods:
https://www.johndcook.com/blog/2009/08/24/algorithms-convert-color-grayscale/

[BeanzMaster]

Very simple

pseudo code :

Code: Pascal  [Select][+][-]

1. Const
2.   Thresold = 128;
3.  
4. For y:=0 to Img.Height-1
5.   for  x:=0 to Img.Width -1
6.   begin
7.     Pixel := img.GetPixel(x,y);    
8.     Intensity := (Pixel.Red+Pixel.Green+Pixel.Blue) div 3;
9.     if intensity <  Thresold then newPixel:= clBlack else newPixel:= clWhite;
10.     BWImg.PutPixel(x,y,NewPixel);
11.  end;
12.  

   

[Thaddy]

Very simple

It IS simple but not for gray scaling. And that was the question. First answer is correct.

[BeanzMaster]

The main question is 

How can i convert multi color to Black and White ??

not to grayscale

The 2nd is for grayscale

how can i convert blue rang color to black&White rang color ??

So by the way now they have the choice