Adding to the answers above: capture the high resolution lattice spacing image, it you can save it as a .dm3 file is ideal! Import the fil in ImageJ, or even Gwyddion software (it's a AFM open access software but works perfect for .tiff file as along as you know the image dimensions). Do a FFT, it will produce a ring pattern, the radius of each ring is the reverse of your d-spacing. Good luck.
You can derive lattice spacing from HRTEM image by using GATAN software which is freely available on the internet. First, download the compatible version of GATAN software and follow the steps as given in the tutorial video.