Learning method and learning apparatus

A learning method comprising:

• converting, by a processor, a first learning image, which is for machine learning of a neural network configured to calculate authentication data for biometric authentication from an input biometric image, into first three-dimensional data by using a first conversion expression based on an internal parameter of an imaging apparatus for capturing the biometric image;
• generating, by the processor, second three-dimensional data by varying a posture of a biological body part included in the first three-dimensional data;
• generating, by the processor, a second learning image by converting the second three-dimensional data by using a second conversion expression that performs inverse conversion of conversion performed by using the first conversion expression;
• and
• executing, by the processor, machine learning of the neural network by using at least the first learning image and the second learning image.

A learning apparatus comprising:

• a memory;
• and
• a processor coupled to the memory and the processor configured to:
• convert a first learning image, which is for machine learning of a neural network configured to calculate authentication data for biometric authentication from an input biometric image, into first three-dimensional data by using a first conversion expression based on an internal parameter of an imaging apparatus for capturing the biometric image,
• generate second three-dimensional data by varying a posture of a biological body part included in the first three-dimensional data,
• generate a second learning image by converting the second three-dimensional data by using a second conversion expression that performs inverse conversion of conversion performed by using the first conversion expression, and
• execute machine learning of the neural network by using at least the first learning image and the second learning image.