Re: [Ifeffit] selection of pixels by criteria

A suggestion: Make a scatterplot available, plotting the pixel-by-pixel values of any two relevant quantities, and make it possible to define a polygon mask on that scatterplot. That often allows separation of chemically-distinct areas. Sincerely, Matthew Marcus On 11/21/2019 12:26 PM, Matt Newville wrote:

HI Troy,

Sorry for the late reply -- I think this sort of slipped off my radar screen.

On Sat, Nov 16, 2019 at 2:09 PM E. Rasbury mailto:troy.rasbury@stonybrook.edu> wrote:

I have used larch some for XRF maps. I like the feature for defining ROI's and then looking at the statistics of the data. I have some samples that are an intimate mix of two or more phases and I would like to extract pixels based on a criteria- like high Sr or low Fe, etc, from across a whole map region. I wonder if this feature is available, or would be easy to create on larch?

Like you say, this is not currently available in the Mapviewer GUI.  But it's a good suggestion and might be possible to do with a small amount of code.

Would it work for you to say "Make an Area with all pixels where Sr Counts is above some value"?  I think that would be easy to generalize from "Sr Counts" to "Ratio of ROI Counts"  (or "analyzed concentration" once I get that done - a work in progress).  If that's right, I think it would be "not hard to add".

--Matt

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