Removing "hot pixels" from map in CalcImage/Surfer?

[Anette von der Handt]

Dear all,

I still have a problem with my machine where spurious intensities (always 256, 512 or rarely 768 counts) show up randomly in my maps (on all 5 spectrometers, maybe the electronics are going "bad"?). This not only looks ugly but we are also doing a lot of quant maps to estimate bulk compositions, so they can skew the data quite a bit.

Does anyone know a good way to exclude the false data points in either CalcImage or Surfer or elsewhere (and re-import) to remove these pixels (my Thermosoftware has a magic "suppress hot pixels" button)? Maybe already has a Matlab script for this to run? Extra points for "filling in" the hot pixel with interpolated data or something similar.

I hope I can eventually figure out what the problem is but until then I would like to save the already acquired maps. Any help or suggestions are appreciated.

Thanks!

[Probeman]

Dear all,

I still have a problem with my machine where spurious intensities (always 256, 512 or rarely 768 counts) show up randomly in my maps (on all 5 spectrometers, maybe the electronics are going "bad"?). This not only looks ugly but we are also doing a lot of quant maps to estimate bulk compositions, so they can skew the data quite a bit.

Does anyone know a good way to exclude the false data points in either CalcImage or Surfer or elsewhere (and re-import) to remove these pixels (my Thermosoftware has a magic "suppress hot pixels" button)? Maybe already has a Matlab script for this to run? Extra points for "filling in" the hot pixel with interpolated data or something similar.

I hope I can eventually figure out what the problem is but until then I would like to save the already acquired maps. Any help or suggestions are appreciated.

Thanks!

First of all: throw an oscilloscope on the spectro pre-amps power supply and look for noise spikes!

As for your existing data, after you quant your maps in CalcImage, you can go into Surfer and select this button:



and then adjust your color levels manually as seen here:



Or even better, simply use the log weight percent output in CalcImage as seen here, for visualizing high and low concentration distributions:

http://probesoftware.com/smf/index.php?topic=55.msg509#msg509

and

http://probesoftware.com/smf/index.php?topic=107.msg402#msg402

You'll still see the noise spikes, but you'll also be able to the see the low level variations.