Different Figure displayed between mapshow() & imshow() for (geo) tif file? - matlab

Question

I'm trying to import data from a .tif file generated in ArcGIS into MATLAB. I know what the final image is supposed to look like because there is a .pdf version of the gridded data posted with the data I've downloaded (so I can check if I've done this correctly).
I have been able to load in the .tif file, but based on how I read the data in & how I plot it, the results look very different. I know that the image I want is closer to the one in imread() and plotted with imshow(). The two images genereated here and the .pdf version I'm trying to recreate are attached. I am wondering
(1) How to colourize this data and
(2) if the differences between these two images are simply the colour scale. Of note, the original .pdf is colourized, but neither my variables 'X' nor 'gridd' have a 3rd dimension that would contain colour info.
filename= 'Na_dep_2017.tif'; % My file
infoii = imfinfo(filename,'tif'); % Get info about my file
[gridd,R] = geotiffread(filename); % Load in geocoded tiff file.
gridd(gridd==str2num(infoii.GDAL_NODATA))=NaN; % Set NANs where we have no data.
[X,cmap] = imread(filename); % Load it in as an image.
X(X==str2num(infoii.GDAL_NODATA))=NaN; % Set NANs where we have no data.
figure(1)
subplot(1,2,1)
imshow(X,cmap); title('Loaded with imread(), plotted with imshow()')
subplot(1,2,2)
mapshow(double(gridd),R);
title('Loaded with geotiffread(), plotted with mapshow()')
Two dif images I make & actual image

Answer 1

I don't think how you load the data in actually changes the image that you get, but it does appear to influence the white-black max/min that the image is displayed with. The two images are therefore not fundamentally different. I got around using either of these methods & without worrying about colorizing the image using rgb channels, because I actually got the data surface that the image is made of by loading the data in. I used pcolor() to display the 'gridd' variable with a standard MATLAB colormap as follows.
filename= 'Na_dep_2017.tif'; % My file
infoii = imfinfo(filename,'tif'); % Get info about my file
[gridd,R] = geotiffread(filename); % Load in geocoded tiff file.
gridd(gridd==str2num(infoii.GDAL_NODATA))=NaN; % Set NANs where we have no data.
figure(1)
h=pcolor(flipud(double(gridd)));
set(h, 'EdgeColor', 'none'); % Makes tightly gridded figure not all black.
colormap(jet)