Electronic endoscope apparatus

An automatic brightness adjusting apparatus for endoscope comprising:

• a pixel luminance detector that detects a luminance level of each pixels in a plurality of pixels, that forms a subject image displayed on a display, in accordance with image-pixel signals read from an image sensor, which is provided in a video-scope;
• an average block luminance calculator that calculates a plurality of average block-luminance-levels for a plurality of blocks, which is defined by dividing the subject image, each of the plurality of average block-luminance-levels indicates a substantial average luminance level of a block and is calculated from a plurality of luminance levels of pixels arranged in corresponding block;
• a peak-luminance determiner that compares the average block-luminance-levels with each other to determine a substantially maximum average block-luminance-level from the plurality of average block-luminance-levels as a peak luminance level;
• a representative luminance calculator that calculates a representative luminance level indicating a brightness of the subject image on the basis of at least the peak luminance level;
• and
• a brightness adjuster that adjusts the brightness of the subject image in accordance with the representative luminance level.

A method for adjusting a brightness of a displayed subject image obtained by using an electronic endoscope apparatus, comprising:

• detecting a luminance level of each pixels in a plurality of pixels, that forms a subject image displayed on a display, in accordance with image-pixel signals read from an image sensor, which is provided in a video-scope;
• calculating a plurality of average block-luminance-levels for a plurality of blocks, which is defined by dividing the subject image, each of the plurality of average block-luminance-levels indicates a substantial average luminance level of a block and is calculated from a plurality of luminance levels of pixels arranged in corresponding block;
• comparing the average block-luminance-levels with each other to determine a substantially maximum average block-luminance-level from the plurality of average block-luminance-levels as a peak luminance level;
• calculating a representative luminance level, which indicates a brightness of the subject image on the basis of at least the peak luminance level;
• and
• adjusting the brightness of the subject image in accordance with the representative luminance level.