The ability to measure the leaf surface area is important to growers. Leaf area information is used to determine healthy growth and the impact of pests. The  8-page step-by-step manual is available here: Leaf Image Analysis Glozer (pdf)

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  Commercial leaf area meters can be portable or lab-based but they typically cost $2500 - $10,000. Furthermore, errors in measurement can be found when leaves are yellowish or wavy¹.
• Digital Leaf Image Analysis is a simple procedure to measure leaf surface area using a digital camera with a tripod, and a frame to hold the leaves.

¹Tsuda, M. 1999. Errors in leaf area measurement with an automatic area meter due to leaf chlorophyll in crop plants. Annals of Botany 84:799-801.