Image processing apparatus and method

An image processing apparatus for converting an input signal in first color space into an output signal in second color space which is different from the first color space, said apparatus comprising:

• a converter, arranged to convert a provided signal in the second color space into a signal in the first color space;
• an extractor, arranged to extract a difference between the signal output by said converter and the input signal;
• a first searcher, arranged to search a signal to be provided to said converter to minimize the extracted difference;
• and
• a second searcher, arranged to search a signal in the vicinity of the signal searched by said first searcher to minimize the extracted difference,
• wherein said first searcher repeats a process for generating a multi-dimensional scalar field in the second color space based on the extracted difference, acquiring a gradient at a search point from the generated scalar field, and updating the search point to lower a potential of the scalar field based on the acquired gradient, so as to search for a signal that minimizes the difference, and
• said second searcher repeats a process for updating the search point to a point having a smaller difference when the difference acquired at least at one point in the neighborhood of the search point is smaller than the difference at the search point so as to search for signal that minimizes the difference.

An image processing method for converting an input signal in first color space into an output signal in second color space which is different from the first color space, said method comprising:

• a conversion step, of converting a provided signal in the second color space into a signal in the first color space;
• an extraction step, of extracting a difference between the signal output in said conversion step and the input signal;
• a search step, of searching a signal to be provided to said conversion step to minimize the extracted difference;
• a generate step, of generating a multi-dimensional scalar field in the second color space based on the extracted difference;
• an acquire step, of acquiring a gradient at a search point from the generated scalar field;
• an update step, of updating the search point to lower a potential of the scalar field based on the acquired gradient;
• and
• a repeat step, of repeating the generate, acquire and update steps so as to search for a signal that minimizes the difference.

An image processing method for converting an input signal in first color space into an output signal in second color space which is different from the first color space, said method comprising the steps of:

• a conversion step, of converting a provided signal in the second color space into a signal in the first color space;
• an extraction step, of extracting a difference between the signal output in said conversion step and the input signal;
• a first search step, of searching a signal to be provided to the conversion step to minimize the extracted difference;
• and
• a second search step, of searching a signal in the vicinity of the signal searched in the first searching step to minimize the extracted difference,
• wherein the first search step comprises:
• a generate step, of generating a multi-dimensional scalar field in the second color space on the basis of the extracted difference;
• an acquire step, of acquiring a gradient at a search point from the generated scalar field,
• an update step, of updating the search point to lower a potential of the scalar field so as to search for a signal that minimizes the difference;
• and
• a repeat step, of repeating the generate, acquire and update steps so as to search for a signal that minimizes the difference;
• and
• in the second search step, a process for updating the search point to a point having a smaller difference when the difference acquired at least at one point in the neighborhood of the search point is smaller than the difference at the search point is repeated so as to search for a signal that minimizes the difference.

A computer readable storage medium storing a computer program for an image processing method for converting an input signal in first color space into an output signal in second color space which is different from the first color space, said computer program comprising:

• code for a conversion step, of converting a provided signal in the second color space into a signal in the first color space;
• code for an extraction step, of extracting a difference between the signal output in said conversion step and the input signal;
• and
• code for a search step, of searching a signal to be provided to said conversion step to minimize the extracted difference,
• code for a generate step, of generating a multi-dimensional scalar field in the second color space based on the extracted difference;
• code for an acquire step, of acquiring a gradient at a search point from the generated scalar field;
• and
• code for a repeat step, of repeating a process for updating the search point to a lower potential of the scalar field, so as to search for a signal than minimizes the difference.

A computer readable storage medium storing a computer program for an image processing method for converting an input signal in first color space into an output signal in second color space which is different from the first color space, said computer program comprising:

• code for a conversion step, of converting a provided signal in the second color space into a signal in the first color space;
• code for an extraction step, of extracting a difference between the signal output in said conversion step and the input signal;
• code for a first search step, of searching a signal to be provided to said conversion step to minimize the extracted difference;
• and
• code for a second search step, of searching a signal in the vicinity of the signal searched in said first search step to minimize the extracted difference,
• wherein the code for the first search step comprises:
• code for a generate step, of generating a multi-dimensional scalar field in the second color space on the basis of the extracted difference;
• code for an acquire step, of acquiring a gradient at a search point from the generated scalar field;
• code for an update step, of updating the search point to lower a potential of the scalar field based on the acquired gradient;
• and
• code for a repeat step, of repeating the generate, acquire, and update steps so as to search for a signal that minimizes the difference;
• and
• in the second search step, a process for updating the search point to a point having a smaller difference when the difference acquired at least at one point in the neighborhood of the search point is smaller than the difference at the search point is repeated so as to search for a signal that minimizes the difference.