Colour encoding clustering

A method of colour converting an image from an input colour encoding to an output colour encoding for use in processing an image, wherein the input colour encoding is associated with a first colour space and the output colour encoding is associated with a second colour space, said method comprising:

• building a set of representative colour encodings for a plurality of candidate colour encodings using a clustering technique, each candidate colour encoding being a specification for interpreting a plurality of encoded colour values to determine appearance of said plurality of encoded colour values, each said representative colour encoding being determined depending on the candidate colour encodings assigned to each of a set of colour encoding clusters, wherein each said representative colour encoding is associated with a colour transform, each of the candidate colour encodings encodes a respective range of colour values, and the respective ranges of the plurality of candidate colour encodings overlap;
• calculating a first perceptual parameter of the input colour encoding;
• determining a second perceptual parameter of at least some of the representative colour encodings;
• comparing the first perceptual parameter and each of the second perceptual parameters;
• selecting a representative colour encoding from the set of colour encodings based on said comparing step;
• and
• colour converting the image to the output colour encoding using the colour transform associated with the selected representative colour encoding.

A system for determining one or more representative colour encodings for use in processing an image, said system comprising:

• a memory for storing data and a computer program;
• a processor coupled to said memory for executing said computer program, said computer program comprising instructions for:
• determining a set of colour encoding clusters based on a clustering criterion related to one or more desired perceptual attributes of a plurality of candidate colour encodings, each candidate colour encoding being a specification for interpreting a plurality of encoded colour values to determine appearance of said plurality of encoded colour values, wherein at least some of the candidate colour encodings are associated with a mapping from a first colour space to a second colour space, each of the candidate colour encodings encodes a respective range of colour values, and the respective ranges of the plurality of candidate colour encodings overlap;
• assigning each candidate colour encoding to one cluster within the set of colour encoding clusters;
• and
• determining a representative colour encoding for each cluster within the set of colour encoding clusters depending on the candidate colour encodings assigned to each cluster.

A non-transitory computer readable medium having a computer program stored thereon for determining one or more representative colour encodings for use in processing an image, said program comprising:

• code for determining a set of colour encoding clusters based on a clustering criterion related to one or more desired perceptual attributes of a plurality of candidate colour encodings, each candidate colour encoding being a specification for interpreting a plurality of encoded colour values to determine appearance of said plurality of encoded colour values, wherein at least some of the candidate colour encodings are associated with a mapping from a first colour space to a second colour space, each of the candidate colour encodings encodes a respective range of colour values, and the respective ranges of the plurality of candidate colour encodings overlap;
• code for assigning each candidate colour encoding to one cluster within the set of colour encoding clusters;
• and
• code for determining a representative colour encoding for each cluster within the set of colour encoding clusters depending on the candidate colour encodings assigned to each cluster.

A system for colour converting an image from an input colour encoding to an output colour encoding for use in processing an image, wherein the input colour encoding is associated with a first colour space and the output colour encoding is associated with a second colour space, said system comprising:

• a memory for storing data and a computer program;
• a processor coupled to said memory for executing said computer program, said computer program comprising instructions for:
• building a set of representative colour encodings for a plurality of candidate colour encodings using a clustering technique, each candidate colour encoding being a specification for interpreting a plurality of encoded colour values to determine appearance of said plurality of encoded colour values, each said representative colour encoding being determined depending on the candidate colour encodings assigned to each of a set of colour encoding clusters, wherein each said representative colour encoding is associated with a colour transform, each of the candidate colour encodings encodes a respective range of colour values, and the respective ranges of the plurality of candidate colour encodings overlap;
• calculating a first perceptual parameter of the input colour encoding;
• determining a second perceptual parameter of at least some of the representative colour encodings;
• comparing the first perceptual parameter and each of the second perceptual parameters;
• selecting a representative colour encoding from the set of colour encodings based on said comparing step;
• and
• colour converting the image to the output colour encoding using the colour transform associated with the selected representative colour encoding.

A non-transitory computer readable medium having a computer program stored thereon for colour converting an image from an input colour encoding to an output colour encoding for use in processing an image, wherein the input colour encoding is associated with a first colour space and the output colour encoding is associated with a second colour space, said program comprising:

• code for building a set of representative colour encodings for a plurality of candidate colour encodings using a clustering technique, each candidate colour encoding being a specification for interpreting a plurality of encoded colour values to determine appearance of said plurality of encoded colour values, each said representative colour encoding being determined depending on the candidate colour encodings assigned to each of a set of colour encoding clusters, wherein each said representative colour encoding is associated with a colour transform, each of the candidate colour encodings encodes a respective range of colour values, and the respective ranges of the plurality of candidate colour encodings overlap;
• code for calculating a first perceptual parameter of the input colour encoding;
• code for determining a second perceptual parameter of at least some of the representative colour encodings;
• code for comparing the first perceptual parameter and each of the second perceptual parameters;
• code for selecting a representative colour encoding from the set of colour encodings based on said comparing step;
• and
• code for colour converting the image to the output colour encoding using the colour transform associated with the selected representative colour encoding.