Abstract

A digital image display apparatus for converting a pixel value of medical digital image data such as MRI image data or CT image data into brightness in accordance with a display window including a window level and a window width of a display unit, determines the optimum window level and width for each image as follows. The apparatus obtains a histogram of pixel values from the digital image data and calculates brightness data of a pixel value having a highest frequency, brightness data of a pixel value at a boundary between a background and an image, area data of a portion having middle brightness within a display brightness range, area data of a portion having maximum brightness, and data indicating a ratio between an area of a portion having higher brightness than the middle brightness and an area of a portion having lower brightness than that obtained, when the digital image is to be displayed by a given display window on the basis of the histogram. The apparatus obtains image quality indicating clarity of the image displayed by the given window on the basis of the above data by using arithmetic operations or by using a neural network, thereby determining the optimum display window which provides a maximum image quality.