Algorithm
Image pre-processing
Read an image and convert it it no grayscale
Blur the image using Gaussian Kernel to remove un-necessary edges
Edge detection using Canny edge detector
Perform morphological closing operation to remove noisy contours
Object Segmentation
Find contours
Remove small contours by calculating its area (threshold used here is 100)
Sort contours from left to right to find the reference objects
Reference object
Calculate how many pixels are there per metric (centi meter is used here)
Compute results
Draw bounding boxes around each object and calculate its height and width