Fake finger determination apparatus and fake finger determination method

A fake finger determination method comprising:

• emitting light directly to an object that is a film attached to a finger;
• capturing a first image of the object at a first mounting area and a second image of the object at a second mounting area including a partial area of the first mounting area;
• comparing a pattern of the first image with a pattern of the second image to identify corresponding characteristic points within the first and second images;
• generating a combined image by superposing the first and second images based on the corresponding characteristic points that have been identified, the combined image having a plurality of pixels having brightness values;
• determining an authenticity of the finger by obtaining brightness values at three or more points from the image combined, calculating an inclination of the brightness values obtained as an attenuation factor, and determining the authenticity of the finger depending on whether the attenuation factor is within a range of attenuation factors that a human finger imaged as the authentication target could exhibit;
• and
• prompting for capture of further images of the object as an input error when a similarity between the patterns is lower than a predetermined threshold.

A computer readable medium storing a program causing a controller to execute fake finger determination processing, the processing comprising:

• emitting light directly to an object that is a film attached to a finger;
• capturing a first image of the object at a first mounting area and a second image of the object at a second mounting area including a partial area of the first mounting area;
• comparing a pattern of the first image with a pattern of the second image to identify corresponding characteristic points within the first and second images;
• generating a combined image by superposing the first and second images based on the corresponding characteristic points that have been identified, the combined image having a plurality of pixels having brightness values;
• determining an authenticity of the finger by obtaining brightness values at three or more points from the image combined, calculating an inclination of the brightness values obtained as an attenuation factor, and determining the authenticity of the finger depending on whether the attenuation factor is within a range of attenuation factors that a human finger imaged as the authentication target could exhibit;
• and
• prompting for capture of further images of the object as an input error when a similarity between the patterns is lower than a predetermined threshold.