Measuring an object from a picture

Using a picture of an object, create a program using a JAVA API or OpenCV to take a picture of an object and measure it's size with high accuracy. . Objects to be measured and the measurements to be made are: - Length, width, and other measurements for a pair or socks or shorts. Both objects have to be present in the same picture, The application should output values measured in mm. Code must be organized, and well-documented. Please ping me for additional details.