Comparison of computer vision system and colour spectrophotometer for colour measurement of mozzarella cheese
P. S. Minz, Charanjiv Singh Saini
Abstract
The colour of food is one of the most important selection criteria affecting purchasing decision of a consumer. Conventionally, colour is measured using colorimeters and colour spectrophotometer. In recent times, computer vision technology has emerged as a robust technique and can be implemented as an alternative to conventional colour measurement methods. A cost-effective computer vision system was developed for measuring the colour of mozzarella cheese with provision to mount different cameras. Various CCD and CMOS based digital cameras were calibrated and evaluated for image acquisition of cheese samples. An additional validation step was introduced to characterize different image acquisition devices on the basis of Root Mean Square Deviation (RMSD) and Mean Normalized Error (MNE). The colour measurement algorithm extracts RGB values from the sample image and coverts into CIE L*a*b* units. The conversion between two colour spaces was done employing standard equations. The colour of mozzarella cheese samples was measured in the CIE L*a*b* color space with the computer vision system (CVS) and commercial colour spectrophotometer. Both the systems yielded equivalent results and developed CVS can be used to study colorimetric quality parameters of mozzarella cheese.