Electronic endoscope system and data processing device

An electronic endoscope system including an endoscope configured to capture an image of biological tissue in an organ spreading in a depth direction and a processor configured to process the captured image of biological tissue, the electronic endoscope system comprising:

• an evaluation value calculation unit configured to obtain an evaluation value indicating an extent of a lesion in biological tissue of each of a plurality of images captured within a predetermined section along a depth direction of a region in the organ;
• an assessment unit configured to assess whether the extent of the lesion is changed in the section based on a degree of variation of the evaluation value;
• and
• a representative value determination unit configured to define a representative value of the section representing the evaluation value in a different method when the extent of the lesion is assessed to be changed and when the extent of the lesion is assessed not to be changed.