Image processing apparatus

An image processing method for calculating an evaluated value for detecting a feature point in an image, the method comprising:

• inputting an image;
• calculating a primary spatial differential value of a brightness value and a secondary spatial differential value of the brightness value with respect to each of a plurality of directions in each pixel of the image;
• estimating a maximum direction and a minimum direction for each pixel, the maximum direction being a direction with which the primary spatial differential value is a maximum value, the minimum direction being a direction with which the primary spatial differential value is a minimum value;
• calculating a first evaluated value of each pixel using the primary spatial differential value in the maximum direction in the pixel, the primary spatial differential value in the minimum direction in the pixel, and the secondary spatial differential value in the maximum direction in the pixel;
• and
• outputting the first evaluated value of each pixel.

A computer-readable program product for causing a computer to perform a process for calculating an evaluated value for detecting a feature point in an image, the process comprising:

• inputting an image;
• calculating a primary spatial differential value of a brightness value and a secondary spatial differential value of the brightness value with respect to each of a plurality of directions in each pixel of the image;
• estimating a maximum direction and a minimum direction for each pixel, the maximum direction being a direction with which the primary spatial differential value is a maximum value, the minimum direction being a direction with which the primary spatial differential value is a minimum value;
• calculating a first evaluated value of each pixel using the primary spatial differential value in the maximum direction in the pixel, the primary spatial differential value in the minimum direction in the pixel, and the secondary spatial differential value in the maximum direction in the pixel;
• and
• outputting the first evaluated value of each pixel.

An image processing apparatus for calculating an evaluated value for detecting a feature point in an image, the apparatus comprising:

• an image input unit for inputting an image;
• a spatial differential value calculation unit that calculates a primary spatial differential value of a brightness value and a secondary spatial differential value of the brightness value with respect to each of a plurality of directions in each pixel of the image;
• a maximum and minimum direction estimation unit that estimates a maximum direction and a minimum direction for each pixel, the maximum direction being a direction with which the secondary spatial differential value is a maximum value, the minimum direction being a direction with which the secondary spatial differential value is a minimum value;
• an evaluated value calculation unit that calculates an evaluated value of each pixel using the secondary spatial differential value in the maximum direction in the pixel, the secondary spatial differential value in the minimum direction in the pixel, and the primary spatial differential value in the maximum direction in the pixel;
• and
• an output unit that outputs the evaluated value of each pixel.

An image processing method for calculating an evaluated value for detecting a feature point in an image, the method comprising:

• inputting an image;
• calculating a primary spatial differential value of a brightness value and a secondary spatial differential value of the brightness value with respect to each of a plurality of directions in each pixel of the image;
• estimating a maximum direction and a minimum direction for each pixel, the maximum direction being a direction with which the secondary spatial differential value is a maximum value, the minimum direction being a direction with which the secondary spatial differential value is a minimum value;
• calculating an evaluated value of each pixel using the secondary spatial differential value in the maximum direction in the pixel, the secondary spatial differential value in the minimum direction in the pixel, and the primary spatial differential value in the maximum direction in the pixel;
• and
• outputting the evaluated value of each pixel.

A computer-readable program product for causing a computer to perform a process for calculating an evaluated value for detecting a feature point in an image, the process comprising:

• inputting an image;
• calculating a primary spatial differential value of a brightness value and a secondary spatial differential value of the brightness value with respect to each of a plurality of directions in each pixel of the image;
• estimating a maximum direction and a minimum direction for each pixel, the maximum direction being a direction with which the secondary spatial differential value is a maximum value, the minimum direction being a direction with which the secondary spatial differential value is a minimum value;
• calculating an evaluated value of each pixel using the secondary spatial differential value in the maximum direction in the pixel, the secondary spatial differential value in the minimum direction in the pixel, and the primary spatial differential value in the maximum direction in the pixel;
• and
• outputting the evaluated value of each pixel.