Hi, I am trying to read the population density data in 2005 and 2015 in Matlab. I am using the following codes.

[pop, R] = geotiffread('gpw-v4-population-density_2005.tif');
figure
mapshow(pop, R);

The reference R looks normal, but the density matrix pop has huge negative numbers in each entry. I also tried to use Mathematica to read the file, and it also does not work. Could you provide us simple examples on how to access your tif file? Thanks!