Posted by
Harry Parker on
Aug 19, 2007; 3:24pm
URL: http://imagej.273.s1.nabble.com/calibrat-to-known-function-tp3698569p3698574.html
Hi Anne,
Since you really want real numbers and not just integer values from 0 to 255, LUT's won't work.
You could use Ulf Dittmer's "Expression" plugin to modify an image with any mathematical expression.
It's at
http://www.ulfdittmer.com/imagej/expression.html
Its a little tricky to learn, but try studying the documentation, then play with it and the example expressions that come with it.
Once you've added your custom expression, you can save it and then write a simple macro that calls the plugin with your saved expression.
--
Harry Parker
Senior Systems Engineer
Digital Imaging Systems, Inc.
----- Original Message ----
From: Anne Salomon <
[hidden email]>
To:
[hidden email]
Sent: Saturday, August 18, 2007 7:20:08 PM
Subject: Re: calibrat to known function
Thanks for your detailed and speedy reply Harry! Unfortunately, my problem
is still not solved. Here's why...
I have made a .lut file just as you said BUT when I use it in ImageJ, the
1-255 pixels, although defined in color, are not defined in the value of the
chlorophyll a they should represent i.e. pixel =(log10 (chla)+2)/0.015.So,
when I make my image the colors are not calibrated to the function above.
So, how do I assign each pixel (that now has the correct color based on my
.lut file) a value of chl a given the above equation?
Thanks again for your help,
Anne
----- Original Message -----
From: "Harry Parker" <
[hidden email]>
To: <
[hidden email]>
Sent: Saturday, August 18, 2007 2:05 PM
Subject: Re: calibrat to known function
> Hi Anne,
>
> An ImageJ LUT can be defined simply as a text file, 257 rows by 4 columns.
> The 1st row contains text. Each following row has 4 integers from 0 to
> 255, separated by tabs: index, red, green, and blue values. Index is
> incremented from 0 to 255. Then for each index give the values wanted for
> red, green and blue. If you want grey values, red, green and blue are set
> equal to each other.
>
> I created something similar using Excel to calculate the LUT numbers.
>
> Rename the file with the extension, ".lut", and place it in a folder named
> "LUTs" in the ImageJ folder.
>
> --
> Harry Parker
> Senior Systems Engineer
> Digital Imaging Systems, Inc.
>
> ----- Original Message ----
> From: Anne Salomon <
[hidden email]>
> To:
[hidden email]
> Sent: Saturday, August 18, 2007 3:44:43 PM
> Subject: calibrat to known function
>
> I am trying to calibrate pixel colors 1-255 of a LUT to a known function:
> pixel=((log x+2))/0.15. How do I do this in image J?
>
> Thanks very much for you insight,
> Anne
>
>
>
>
>
>
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