Hi,
Thanks for your comment.
I just learned that a .fig file is simply a .mat file with a different extension, so if you don't want to actually render the image you can do
>> s = load('filename.fig','-mat');
to load the data as a structure into the workspace and yield the variable values in the 'children' field of the structure. Doing this has saved me a lot of processing and heartache. Please find a basic version of mine below for reference.
Kind regards, Kista Susan
% Code to yield the mean of a user defined region in a saved .fig plot
clear; clc;
uiopen('file.fig',1);
h = imrect(gca,[]); % draw region of interest
api = iptgetapi(h);
position2 = (api.getPosition());
position = uint32(position2);
s = load('file.fig','-mat');
% Output mean index value for this region; note: I used an original subplot so my data of interest was in children(3,1).
format short;
mean_v = mean2(s.hgS_070000.children(3,1).children(1,1).properties.CData(position(2):position(2)+position(4),position(1):position(1)+position(3)));
close all;