Charged particle beam apparatus and image adjustment method

A charged particle beam apparatus configured to acquire an image by scanning a specimen with a charged particle beam, the charged particle beam apparatus comprising:

• an optical system configured to scan the specimen with the charged particle beam;
• a detector configured to detect a signal generated by scanning the specimen with the charged particle beam;
• a contrast adjustment circuit configured to adjust contrast of the image by controlling a gain of the detector in accordance with a contrast value;
• a brightness adjustment circuit configured to adjust brightness of the image;
• and
• a control unit configured to control the contrast adjustment circuit and the brightness adjustment circuit,
• the control unit acquiring information on luminance of a reference image in a non-signal state, and information on an average value of luminance of each pixel of the reference image,
• the control unit controlling the brightness adjustment circuit, based on the acquired information on luminance of the reference image in the non-signal state,
• the control unit acquiring the image in a state where the brightness adjustment circuit is controlled,
• the control unit determines the contrast value, based on the average value of luminance of each pixel of the reference image, and
• the control unit adjusting the contrast of the acquired image by controlling the contrast adjustment circuit, based on the contrast value.