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Re: plot profile problems with pixel value

Posted by Rigo Pantoja on Apr 10, 2008; 11:39pm
URL: http://imagej.273.s1.nabble.com/plot-profile-problems-with-pixel-value-tp3696589p3696593.html

Jonathan,

The problem is fixed in version 1.40e.  Thanks,

Rigo

On Thu, Apr 10, 2008 at 1:51 PM, Jonathan Hilmer <[hidden email]> wrote:

> I think the problem you're seeing arises from the spatial definitions
> and representations of each pixel.  Rather than go through a lengthy
> explanation, try using the point selection tool and Measurements
> (which will give the same results as Plot Profile and is faster to
> check) when zoomed in.  You'll see the effect causing your results,
> which actually arises from a very methodical way of processing the
> pixelated data.
>
> The slight difference I see between the point selection tool and line
> selections is that the line selections seems to go to the nearest
> pixel "corner" for a measurement while the point selection is always
> to the upper-left.
>
> Jonathan
>
>
> On Thu, Apr 10, 2008 at 2:14 PM, Rigo Pantoja <[hidden email]>
> wrote:
> > Hi Harry,
> >
> >  Wayne recommened your suggestion.  It did not work.
> >
> >  Basically, when you zoom in and draw a line across a set of linear
> pixels,
> >  you get a variable reading of the pixel value if the line does not
> cross the
> >  pixel in the exact center.  If your pixels values are high you might
> not
> >  notice.  However, if you are analyzing single-molecues - where every
> count
> >  matters - this becomes obvious.
> >
> >  If you follow the thread you can see this effect with a sample image
> >  (fluorescentcells), which after you convert it to a 16bit tiff file.
> >
> >  Thanks,
> >
> >  Rigo
> >
> >  On Thu, Apr 10, 2008 at 10:34 AM, Harry Parker <[hidden email]>
> >  wrote:
> >
> >
> >
> >  > Have you tried deselecting the menu option, Edit->Options->Profile
> Plot
> >  > Options...->Interpolate Line Profiles?
> >  >
> >  > --
> >  > Harry Parker
> >  > Senior Systems Engineer
> >  > Digital Imaging Systems, Inc.
> >  >
> >  > ----- Original Message ----
> >  > From: Rigo Pantoja <[hidden email]>
> >  > To: [hidden email]
> >  > Sent: Wednesday, April 9, 2008 2:35:21 PM
> >  > Subject: plot profile problems with pixel value
> >  >
> >  > All,
> >  >
> >  > The plot profile (Ctrl+K)  is yielding different values for the same
> >  > pixel.
> >  > I Noticed this when I generated plot profiles for an individual spot
> along
> >  > the x and y axis.   The  peak  pixel  value was different for the
> comon
> >  > interesection.  Also, if you generate a various plot profiles for
> with
> >  > increasing lengths, the peak pixel value changes.  Can this bug be
> fixed?
> >  >
> >  > Thanks,
> >  >
> >  > Rigo
> >  >
> >  >
> >  >
> >  >
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