System and method for counting zooplankton

A method for density measurement of zooplankton in situ in an aqueous solution, the method comprising:

• acquiring at least one image of a volume V of the aqueous solution;
• processing the at least one image and identifying particles in the image;
• analyzing the identified particles based on a sharpness of each particle, and
• identifying zooplankton to be counted;
• wherein analyzing a sharpness of each particle further comprising:
• tracing a boundary of each identified particle,
• calculating an intensity gradient for each pixel along the boundary of each particle from the at least one image based on a rate of change of intensity between neighboring pixels, and
• calculating a mean intensity gradient of all the pixels along the boundary of each particle.

A system for density measurement of zooplankton in situ in an aqueous solution, comprising:

• an imaging device for acquiring at least one image of a volume V of the aqueous solution;
• a plate arranged at a distance from the imaging device, the distance and a view angle of the imaging device defining the volume V of the aqueous solution imaged by the imaging device;
• and
• an image processing device performing image processing of the at least one image from the imaging device identifying particles in the image, analyzing the identified particles based on a sharpness of each particle, and identifying zooplankton to be counted;
• wherein analyzing a sharpness of each particle further comprising:
• tracing a boundary of each identified particle,
• calculating an intensity gradient for each pixel along the boundary of each particle from the at least one image based on a rate of change of intensity between neighbouring pixels, and
• calculating a mean intensity gradient of all the pixels along the boundary of each particle.