backgrounds

[Bill Rothman]

Hello,
 
I acquire RGB images on which I must substract those pixels with RGB
values greater than (240,225,185).for example, ("background") and  set
them to (0,0,0) BUT leave other pixels (with my information) alone. I
guess I could write a macro, but was wondering if someone (most likely)
has done this already.
 
 I also want to increase the intensity of the dimmer untouched pixels
(intensify the low intensity pixels)  in some non-linear fashion, maybe
log scale.
 
Any feedback welcomed.
 
Thanks,
Bill

[Joachim Wesner]

Hi Bill,

it would be pretty easy to write a simple macro to do this, I do not know
of a ready-to-run plugin that does this. however, if you want to avoid
macro programming, you might
want to take a look at the Expression(NT) plugin that - it seems - would
only require you to define some simple formulas to describe your task, and,
as the result is compiled
into "native" Java code, it should run pretty fast if you want to use it on
a larger # of images:

http://www.ulfdittmer.com/imagej/expression.html

Joachim

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Hello,

I acquire RGB images on which I must substract those pixels with RGB
values greater than (240,225,185).for example, ("background") and  set
them to (0,0,0) BUT leave other pixels (with my information) alone. I
guess I could write a macro, but was wondering if someone (most likely)
has done this already.

 I also want to increase the intensity of the dimmer untouched pixels
(intensify the low intensity pixels)  in some non-linear fashion, maybe
log scale.

Any feedback welcomed.

Thanks,
Bill



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[David Webster]

Bill,

I think landini's threshold color plugin will solve your first problem.
Select RGB mode, the set each band to "stop". This trhresholds out eveything
above a level. You do this for each band. Landini's plugin's can be found
via ImageJ's web page Plugins/Links to External Sites/Gabriel Landini.

David Webster

On Mon, Nov 9, 2009 at 11:31 AM, Rothman, William <
[hidden email]> wrote:

> Hello,
>
> I acquire RGB images on which I must substract those pixels with RGB
> values greater than (240,225,185).for example, ("background") and  set
> them to (0,0,0) BUT leave other pixels (with my information) alone. I
> guess I could write a macro, but was wondering if someone (most likely)
> has done this already.
>
>  I also want to increase the intensity of the dimmer untouched pixels
> (intensify the low intensity pixels)  in some non-linear fashion, maybe
> log scale.
>
> Any feedback welcomed.
>
> Thanks,
> Bill
>