Function image display method and device

A method of displaying image comprising a step of collecting image data of a person being examined, a step of forming a tomogram from said image data, a step of calculating at least one biological function data from said tomogram, a step of forming at least one function image based on said biological function data, a step of forming an operated image by operating said function images together, for forming a composite image by composing said tomogram and at least one of the following images;

• an operated image obtained by operating said functional images together, a composite image obtained by composing said functional images together, said operated image, and said functional image;
• and a display step capable of displaying said functional image, said operated image, said tomogram and said composite image, wherein the step of forming said functional image and the step of forming the composite image work to display at least portions of the regions in said functional image and in said operated image on an arbitrary gradation color scale corresponding to the evaluated value of said biological function data, and other regions in said functional image and in said operated image are displayed in an arbitrary color which is not included in said gradation color scale, or are displayed transparently.