[magick-users] Reducing number of Colo(u)rs

[Anthony Thyssen]

On Tue, 28 Apr 2009 15:33:45 +0100
"Roger Lee, NOTiFY" <rlee at notify.co.uk> wrote:

| I run the following command on my JPEG;
| 
|  
| 
| convert "Water lilies.jpg" -quantize YIQ -dither None -colors 3
| "Water_Lilies_3_QYIQ_NO.jpg"
| 
|  
| 
| Expecting the "colors 3" parameters to reduce the image to just three
| colours. 
| 
|  
| 
| When I read the image pixel by pixel and count and aggregate the RGBs I find
| that there a lot more than three RGB combinations. Though there are
| predominately three larger RGB combinations. 
| 
|  
| 
| What am I doing wrong?
| 
What version of IM?

Can you put the image online somewhere so we can download and test
against the latest release?


Fred:  dither setting should make no difference, it is supposed to
represent the method by which IM decides what pixel gets what color
so as to produce the best representation of the original image using
the reduced color scheme.


  Anthony Thyssen ( System Programmer )    <A.Thyssen at griffith.edu.au>
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