Posted by
Jacqueline Ross on
Jun 02, 2010; 6:29am
URL: http://imagej.273.s1.nabble.com/RGB-to-CMYK-tp3688100p3688105.html
Hi Kate,
You could also try Gabriel Landini's other great plugin: Threshold
Colour (
http://www.dentistry.bham.ac.uk/landinig/software/software.htmland
http://imagejdocu.tudor.lu/doku.php?id=plugin:color:threshold_colour:start ). This helps with separating out hues so might work quite well for
the colours you describe. I have some additional notes that I wrote for
our users that I could send you also if you are interested. They are
also available on our website.
Kind regards,
Jacqui
Jacqueline Ross
Biomedical Imaging Microscopist
Biomedical Imaging Research Unit
School of Medical Sciences
Faculty of Medical & Health Sciences
The University of Auckland
Private Bag 92019
Auckland, NEW ZEALAND
Tel: 64 9 373 7599 Ext 87438
Fax: 64 9 373 7484
http://www.fmhs.auckland.ac.nz/sms/biru/-----Original Message-----
From: ImageJ Interest Group [mailto:
[hidden email]] On Behalf Of
Kateo
Sent: Wednesday, 2 June 2010 6:07 a.m.
To:
[hidden email]
Subject: Re: RGB to CMYK
HI Stephan,
Thank you very much for your reply! I appreciate your insight, and
agree that perhaps I don't need to convert my image to CMYK.
I have tried using the color deconvoluter. However, I do not believe
it will work with the type of images I am looking at. We stained them
with picrosirius red to enhance the bifringency of collagen. We then
looked at the slides under polarized microscopy and from that took
pictures of the light that passed through the polarizing plates and
collagen. So since the color in my pictures is not due to a stain but
due to light passing through collagen of different thickness, I think
this plug in is of no help, unfortunately.
I am still trying to figure out how to get a % of red/orange and
green/yellow that are in my pictures since mature collagen in
red/orange and immature collagen is yellow/green.
If you have any further ideas or advice, please pass it on! I'm green
behind the ears and am slowly getting discouraged.
Thanks very much,
Kate
Quoting "Stephan Saalfeld [via ImageJ]"
<
[hidden email]>:
>
>
>
> In the trivial case, that is when the intensity value stored for each
> color channel is linear, grey is ( red + green + blue ) / 3 and no
color
> profiles are in the way, the conversion is quite easy. Let r, g and b
> be red, green and blue in unsigned byte range [0...255] and calculate
c,
> m, y and k as floating point in range [0...1]:
>
> c = 1.0 - r/255.0
> m = 1.0 - g/255.0
> y = 1.0 - b/255.0
>
> That's CMY from which CMYK is derived by extracting the grey component
> into a fourth channel and scaling the remaining color channels
> respectively:
>
> k = min( c, y, k )
> if ( k == 1.0 )
> c = m = y = 0
> else
> s = 1.0 - k
> c = ( c - k ) / s
> m = ( m - k ) / s
> y = ( y - k ) / s
>
> For the application, you have in mind, I do not think that conversion
> into CMYK is of any help. It does not add any information to your
data.
> Better look at Gabriel Landini's Colour Deconvolution plugin and
> directly estimate the percentage of the colors you're looking for:
>
>
http://www.dentistry.bham.ac.uk/landinig/software/cdeconv/cdeconv.html>
> Best,
> Stephan
>
>
>
> On Thu, 2010-05-13 at 06:44 -0700, Kateo wrote:
>> HI Duane,
>> I was wondering if you could expand on how to convert RGB--> CMYK. I
have no
>> clue about these things, but I found a paper that before analyzing
the
>> colours in histological sections performed colour separation into
CMYK
>> before dertermining the % of colours in their section. I want to
determine
>> the % of orange/red vs. green colour in my sections stained with
picrosirius
>> red and viewed under a polarized microscope. Anyway, I would
appreciate your
--
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