STEP 2
Now we need to determine the dimension of our image. Go to Image>Canvas Size or you can press Ctrl+Alt+C/Cmd+Opt+C. In my case the dimension is 1908 by 1303 pixels and 1908 is bigger than 1303 which shows that my image is landscape format rather than portrait format. Now we need to do a little calculation. We need the multiply the width of the image with 0.007 if your image is in landscape format otherwise multiply the height with 0.007. If I multiply 1908 with 0.007, I’ll get 13.356. Now I need to remember this value and you need to remember yours.