How to label pixel image with the original unit???

Hi everyone i am using FDTD software which give me data in the form of pixels when i plot that data in the MATLAB it give me image with number of pixels on X and Y axis how can i convert that pixels into original units like the images which i got from FDTD??? please check the attached files first image is from software and second image is from MATLAB i want to covert matlab image exactly like first image. Please tell me the code

<<

>>