Electronic endoscope apparatus and method of controlling image luminance for electronic endoscope apparatus

An electronic endoscope apparatus comprising a scope having an imaging device for imaging an observation target and illumination means for illuminating the observation target, the electronic endoscope apparatus comprising:

• halation detection means for detecting halation of a predetermined level or higher occurring in an image represented by an image signal obtained by the imaging device, based on the image signal;
• light amount adjustment means for reducing an amount of light emitted from the illumination means so as to cause the halation to become a predetermined level or lower according to detection of the halation by the halation detection means;
• and
• luminance conversion means for processing the image signal so that the image represented by the image signal becomes a luminance conversion image,
• wherein only a dark area having a predetermined luminance or lower in the image caused by reduction in the amount of the light has been converted to have a higher luminance, and
• wherein the luminance conversion means generates from the image signal a blurry image representing a low frequency component of the original image represented by the image signal, obtains a non-linear conversion image by carrying out conversion of luminance of a part exceeding a predetermined luminance in the blurry image into zero luminance and by carrying out conversion of luminance of a part having the predetermined luminance or lower into a converted luminance corresponding to the original luminance, and obtains the luminance conversion image by adding the non-linear conversion image to the original image.