Image processing device and medical treatment device including the same

An image processing device (1) is disclosed herein to process a fluorescent image obtained from a tissue of a subject being irradiated with excitation light, which tissue is rendered photosensitive with a fluorescent agent, the fluorescent image (FI) comprising an array of pixels having respective fluorescent signal values. The image processing device is configured to identify transition positions where zero-crossings in a modified contrast to noise ratio vector (CNRLM(...) ) occur and based on the identified transition positions to indicate a border in the fluorescent image that is representative for a margin between tumor containing tissue and healthy tissue, wherein the contrast to noise ratio vector (CNRLM(...) )is defined as: CNRLMp=FLp−FB−c⋅Sc⋅S. Therein FL(...) is a fluorescent signal vector for a scan trajectory L in the fluorescent image FI of which respective values are an indication of a magnitude of the fluorescent signal in the fluorescent image FI at respective positions p of the scan trajectory L, FB is a reference fluorescent signal being an average value of reference fluorescent signal values of the fluorescent image, S is a standard deviation of the reference fluorescent signal values and c is a predetermined constant.