calculate distance with ref line in an image

I want to calculate the distance between the curved line as in my image and left line i.e reference line (grid line).distance should be in between the correspondence points of ref line and curved line basically I need depth so I am thinking like that to calculate the depth if my method is wrong plzz suggest or provide solution calibration detail: square box is of 1cm in real world and output will be in cm or in microns

[praveen rai]

i have searched related to my query and I have found 1 matlab code uploaded by @image anaylyst. I have run this code but calibrate function is running but measure distance function is not running uploading mat file anyone help me out I have provided the code