How to subtract false color gradient ?

Hi! I am trying to subtract a False color gradient from my image. I tried using the "detrend" function to subtract the polynomial trend, but it seems like I might be subtracting too much. I get some weird lines across my image.

This is the image before the gradient correction:

and this is how it looks after:

And this is my code:

% Calculate strain
strainNorm = (dspacingNorm - dspacingNominal) / dspacingNominal;
% Gradient Correction
D = detrend(strainNorm,1,'omitmissing');
figure;  imagesc(xbins,ybins,D * 100);  
title('Elastic lattice strain (%)');  colorbar;  axis square;  axis equal; % axis([0 xbins(end) 0 ybins(end)])
colormap jet;  caxis([strainMin strainMax]) 
set(gca,'xtick',[]);  set(gca,'xticklabel',[]);  set(gca,'ytick',[]);  set(gca,'yticklabel',[])

Thank you!

Answer 1

[Matt J]

detrend() operates column by column. I suspect you can avoid the lines by subtracting a plane fit to the whole surface instead, e.g., using planarFit() from this FEX download,

https://www.mathworks.com/matlabcentral/fileexchange/87584-object-oriented-tools-for-fitting-conics-and-quadrics

[Edith Celeste]

Maybe I am not applying it right, but planarFit() is not working for my code

[Matt J]

Maybe I am not applying it right

I would have to assume that.