Re: using a scanner as a densitometer?

Hi all,

R is great, but the learning curve is very steep, esp. for
non-programmers (like myself). I have used it a bit, and have colleagues
who swear by it. I've never found the time to learn it well enough for
routine use, though.

I would like to suggest an alternative that may suit more people: ImageJ
(may be downloaded freely from http://rsb.info.nih.gov/ij/index.html)

Many scientists use ImageJ to evaluate electrophoresis gels. This is
basically an application of densitometry! Indeed, many of the image
analysis options in ImageJ has a component related to densitometry.

ImageJ is simple to use.

I think doing a simple line profile along a step tablet should be
adequate for most applications. ImageJ would have to be calibrated (see
http://rsb.info.nih.gov/ij/docs/examples/calibration/index.html). When
that's done, all you have to do is to draw a line (or a rectangle for
better averaging) along the step tablet, and press ctrl-K to plot the
profile. Actual values may be read right off the y-axis, or by using the
list function in the plot window.

This approach may not be entirely accurate, but I would be surprised if
the inaccuracy is large enough to cause problems in
alt-photo-applications. If better accuracy is needed, I think a real
densitometer is the way to go.

Best regards,
Tom Einar Andersen
Received on Wed Feb 22 07:33:44 2006