Converting .tif file into an .ascii file

I have a .tif file that i would like to convert to .ascii . Or a way to be able to convert the .tif file into a numerical matrix where i can convert some values to NaN. I have tried:

Trial 1:

t = Tiff('File_name.tif','r');

imageData = read(t);

imagesc(imageData)

Trial 2:

A = imread('maxlike34_ica_34minerals_step3_2ppd_mostdominant_tiff.tif');

save('myTiff2mat','A');

In both trials when i run a loop to convert any cells that contain a 0 to NaN then none of them change and they all remain as 0, and the .mat files have the dimensions and uint8 which is unlike any data file that i import using .ascii files.

[KSSV]

Is it a geotiff file?

[Ahmed Abdulla]

im not really familiar with the term, but the file is compositional measurement of an area and where there is no recorded measurement the filler value is 0.

[KSSV]

Attach your file.

[Ahmed Abdulla]

sorry im not allowed to do so, thank you for trying to help! i'll keep trying