Method for estimating chlorophyll content of a leaf

A method of estimating chlorophyll content of a leaf, which method comprises:

• providing a device, wherein the device comprises:
• a mobile computing device comprising a digital camera;
• and a peripheral removably attached to the mobile computing device, the peripheral comprising a light source aligned with the digital camera when the peripheral is removably attached to the mobile computing device such that the light source may illuminate a lens of the digital camera, wherein the light source is adapted to emit light at least partly absorbable by chlorophyll pigments, chlorophyll a and chlorophyll b, and wherein the peripheral provides for a space between the light source and the digital camera such that the leaf may be interposed between the digital camera and the light source;
• capturing by the digital camera a first image of the light source turned on without the leaf interposed between the digital camera and the light source;
• retrieving exposure data of the first image;
• capturing by the digital camera a second image with the leaf interposed between the digital camera and the turned on light source;
• retrieving exposure data of the second image;
• and
• using a processor, estimating the chlorophyll content of the leaf based on the retrieved exposure data of the first and second images, wherein the processor estimates the chlorophyll content of the leaf based on at least one of exposure time, F-number, and ISO value of the first and second images.