Adding images in a stack

[ml]

I am currently working with fairly simple tiff image stacks that are 8 bit monochrome, and are the result of simulating beam profiles.  We want to approximate what happens when we overlap a few of the beams.  So, we want saturated pixels to stay saturated so that we can see how the screen is filling up.  

I tried using the "sum" option in the "image > stack > Z Project" menu.  However, it gives me a 32-bit image and rescales the contrast, throwing off the saturated pixels.  What I want is something that adds the pixels directly.  If they add to over 255, just set equal to 255 and keep it an 8-bit image.  Is there any way to do this easily without writing my own plug-in?

Thanks  

[Michael Schmid]

Hi,

"sum" with Image>Stack>Z Project should not do any scaling. The 8-bit
value 255 will correspond to the 32-bit value 255, but, of course there
can be larger values (use Process>Math>Max to get rid of them if
undesired). It will be scaled if you convert it back to 8-bit with
Edit>Options>Conversions "Scale when converting" checked.
Without this option, all float values larger than 254.5 will become 8-bit
255.

Michael

______________________________________________________________________

On Wed, July 8, 2009 00:06, ml wrote:

> I am currently working with fairly simple tiff image stacks that are 8 bit
> monochrome, and are the result of simulating beam profiles.  We want to
> approximate what happens when we overlap a few of the beams.  So, we want
> saturated pixels to stay saturated so that we can see how the screen is
> filling up.
>
> I tried using the "sum" option in the "image > stack > Z Project" menu.
> However, it gives me a 32-bit image and rescales the contrast, throwing
> off
> the saturated pixels.  What I want is something that adds the pixels
> directly.  If they add to over 255, just set equal to 255 and keep it an
> 8-bit image.  Is there any way to do this easily without writing my own
> plug-in?
>
> Thanks