Image conversion parameter calculation device, image conversion parameter calculation method, and program

An image conversion parameter calculation device comprising:

• a pixel selection unit which randomly selects pixels of a predetermined number or pixels of not more than the predetermined number from a first image;
• and
• a parameter derivation unit which derives a conversion parameter concerning the selected pixels selected by the pixel selection unit, the conversion parameter being a parameter for converting, to the first image, a second image that is subject to image alignment with the first image, by repeatedly performing as follows, until a conversion parameter update becomes to be smaller than a first threshold;
• calculating the conversion parameter update by
• calculating, for each selected pixel, a product of a transposed matrix of a sub-product of derivative for each selected pixel and a Jacobian matrix in each of the selected pixels, and an error between pixel value at a converted pixel location when converting the pixel in the second image corresponding to the selected pixel and pixel value of the selected pixel in the first image, and
• calculating a sum of the products,
• and
• updating the conversion parameter, by composition of the conversion parameter for converting the pixel in the second image with the conversion parameter update,
• wherein the pixel selection unit includes:
• a pixel extraction unit which randomly extracts a pixel from the first image;
• and
• a criterion determination unit which determines whether or not the pixel extracted by the pixel extraction unit is a pixel in a noise region in the first image by using a bilateral filter, and selects the pixel as the pixel used for deriving the conversion parameter on a condition that the pixel is not a pixel in the noise region.

An image conversion parameter calculation method comprising:

• randomly selecting pixels of a predetermined number or pixels of not more than the predetermined number from a first image;
• and
• deriving a conversion parameter concerning the selected pixels, the conversion parameter being a parameter for converting, to the first image, a second image that is subject to image alignment with the first image, by repeatedly performing as follows, until a conversion parameter update becomes to be smaller than a first threshold;
• calculating the conversion parameter update by
• calculating, for each selected pixel, a product of a transposed matrix of a sub-product of derivative for each selected pixel and a Jacobian matrix in each of the selected pixels, and an error between pixel value at a converted pixel location when converting the pixel in the second image corresponding to the selected pixel and pixel value of the selected pixel in the first image, and
• calculating a sum of the products,
• and
• updating the conversion parameter, by composition of the conversion parameter for converting the pixel in the second image with the conversion parameter update, and
• randomly extracting a pixel from the first image;
• and
• determining whether or not a partial derivative in the extracted pixel is not smaller than a second threshold, and selecting the pixel as a pixel used for deriving the conversion parameter on a condition that the partial derivative is not smaller than the second threshold.

An image conversion parameter calculation method comprising:

• randomly selecting pixels of a predetermined number or pixels of not more than the predetermined number from a first image;
• and
• deriving a conversion parameter concerning the selected pixels, the conversion parameter being a parameter for converting, to the first image, a second image that is subject to image alignment with the first image, by repeatedly performing as follows, until a conversion parameter update becomes to be smaller than a first threshold;
• calculating the conversion parameter update by
• calculating, for each selected pixel, a product of a transposed matrix of a sub-product of derivative for each selected pixel and a Jacobian matrix in each of the pixels, and an error between pixel value at a converted pixel location when converting the pixel in the second image corresponding to the selected pixel and pixel value of the selected pixel in the first image, and
• calculating a sum of the products,
• and
• updating the conversion parameter, by composition of the conversion parameter for converting the pixel in the second image with the conversion parameter update, and
• randomly extracting a pixel from the first image;
• and
• determining whether or not the extracted pixel is a pixel in a noise region in the first image by using a bilateral filter, and selects the pixel as the pixel used for deriving the conversion parameter on a condition that the pixel is not a pixel in the noise region.

A non-transitory computer readable information recording medium storing an image conversion parameter calculation program, when executed by a processor, performs a method for:

• selecting pixels of a predetermined number or pixels of not more than the predetermined number from a first image;
• and
• deriving a conversion parameter concerning the selected pixels, the conversion parameter being a parameter for converting, to the first image, a second image that is subject to image alignment with the first image, by repeatedly performing as follows, until a conversion parameter update becomes to be smaller than a first threshold;
• calculating the conversion parameter update by
• calculating, for each selected pixel, a product of a transposed matrix of a sub-product of derivative for each selected pixel and a Jacobian matrix in each of the selected pixels, and an error between pixel value at a converted pixel location when converting the pixel in the second image corresponding to the selected pixel and pixel value of the selected pixel in the first image, and
• calculating a sum of the products,
• and
• updating the conversion parameter, by composition of the conversion parameter for converting the pixel in the second image with the conversion parameter update, and
• randomly extracting a pixel from the first image;
• and
• determining whether or not a partial derivative in the pixel extracted by the extraction pixel is not smaller than a second threshold, and selecting the pixel as a pixel used for deriving the conversion parameter on a condition that the partial derivative is not smaller than the second threshold.

A non-transitory computer readable information recording medium storing an image conversion parameter calculation program, when executed by a processor, performs a method for:

• randomly selecting pixels of a predetermined number or pixels of not more than the predetermined number from a first image;
• and
• deriving a conversion parameter concerning the selected pixels, the conversion parameter being a parameter for converting, to the first image, a second image that is subject to image alignment with the first image, by repeatedly performing as follows, until a conversion parameter update becomes to be smaller than a first threshold;
• calculating the conversion parameter update by
• calculating, for each selected pixel, a product of a transposed matrix of a sub-product of derivative for each selected pixel and a Jacobian matrix in each of the selected pixels, and an error between pixel value at a converted pixel location when converting the pixel in the second image corresponding to the selected pixel and pixel value of the selected pixel in the first image, and
• calculating a sum of the products,
• and
• updating the conversion parameter, by composition of the conversion parameter for converting the pixel in the second image with the conversion parameter update, and
• randomly extracting a pixel from the first image;
• and
• determining whether or not the extracted pixel is a pixel in a noise region in the first image by using a bilateral filter, and selects the pixel as the pixel used for deriving the conversion parameter on a condition that the pixel is not a pixel in the noise region.