Using ImageJ for image processing and analysis requires some basic computer literacy and installation of a compatible version of Java software ( ). Data cannot be obtained until images are analyzed. Leaf area measurements involve two separate steps: image acquisition and image analysis. Photographs can be saved with metadata, such as geolocation, date, and time, automatically. Images themselves are very good visual data. Measurements can be performed on the same leaf repeatedly, making it possible to monitor leaf growth over time.
The apparatus is portable and produces acceptable image quality for image analysis under many different environmental conditions (Figure 2). The image processing and analysis is quick-typically 1.5 to 2 minutes per image.
Also, ImageJ is a public domain program, and it is free to download. The apparatus only requires inexpensive, ordinary office supplies. The advantages and disadvantages of this technique are as follows: Leaf images are then processed and analyzed to measure leaf area using ImageJ, an open-source image processing program. The imaging apparatus is made with ordinary office supplies and designed to easily obtain leaf images in greenhouse or field environments. This article introduces a simple, inexpensive, and portable image-based technique for nondestructive leaf area measurements (Figure 1).
The major drawback of leaf scanners is their high instrument cost. Their optical measurements are highly accurate. Stationary scanners with conveyor belts are used for destructive measurements, whereas portable palette- or wand-style scanners are used for nondestructive measurements. Various types of commercial leaf scanners are available. More modern techniques involve imaging leaves by scanners or cameras, followed by optical measurements or image analysis (Easlon and Bloom 2014). 2000) are rarely used in current horticultural research because of the time-consuming measurement processes. Traditional techniques such as grid count, paper weighing, and planimeter methods (Chaudhary et al. Leaf area can be measured destructively or nondestructively. Leaf area data can also convert the unit of other measurements, such as photosynthesis and transpiration, from per-unit leaf area to per leaf, enabling the assessment of leaf or whole-canopy physiology. Leaf area is an important horticultural trait that reflects plant health, growth, and environmental stress (Gonzalez et al. The image apparatus in this photograph is described in Figure 3. Capturing a pepper leaf image nondestructively in the field. Other ImageJ tutorial videos are also available at. The tutorial video for this article is available at the UF IFAS Horticultural Crop Physiology Lab YouTube channel ( ).
This article is part of a series introducing various image-based measurements for horticultural research. This technique is particularly useful to researchers and students studying leaf growth and physiology in greenhouse or field environments. Leaf area data can also be used to assess leaf or whole-canopy physiology by converting the unit of other nondestructive measurements, such as photosynthesis and transpiration, from per-unit leaf area to per leaf. Because both image capture and analysis are performed nondestructively, leaf area can be measured on the same leaf repeatedly, enabling the monitoring of leaf growth over time. It uses an imaging apparatus made with ordinary office supplies to obtain leaf images in greenhouse or field environments.
Shinsuke Agehara, Lillian Pride, Mariel Gallardo, and Jose Hernandez-Monterroza