Method and system for removing noise from digital data

A system for removing noise from digital data by median filtering data elements of the digital data, the data elements comprising numerical values, the system comprising:

• one or more processors configured to:
• obtain N data elements, where N is an integer value greater than one;
• arrange the N data elements into a list with N positions 1 to N;
• carry out a series of sorting cycles which alternate between a first sorting cycle and a second sorting cycle, wherein:
• in each first sorting cycle, the numerical values of pairs of data elements in a first set of adjacent positions are compared, and the positions of the data elements in each pair are selectively swapped based on a result of the respective comparison;
• in each second sorting cycle, the numerical values of pairs of data elements in a second set of adjacent positions are compared, the second set of adjacent positions being different from the first set of adjacent positions, and the positions of the data elements in each pair are selectively swapped based on a result of the respective comparison;
• and
• the N data elements are arranged into an ordered list which is ordered in order of their numerical values;
• either:
• output the data element, or the numerical value of the data element, in position (N+1)/2 if N is an odd number;
• or output an average of the numerical values of the data elements in positions N/2 and (N+1)/2 if N is an even number;
• or
• output an average of the numerical values of a group of data elements centred on a mid-point of the ordered list;
• and
• use the output as a median value of the N data elements.

A non-transitory computer-readable medium comprising instructions for removing noise from digital data by median filtering data elements of the digital data, the data elements comprising numerical values, wherein the instructions, when executed by one or more processors, cause the one or more processor to:

• obtain N data elements, where N is an integer value greater than one;
• arrange the N data elements into a list with N positions 1 to N;
• carry out a series of sorting cycles which alternate between a first sorting cycle and a second sorting cycle, wherein:
• in each first sorting cycle, the numerical values of pairs of data elements in a first set of adjacent positions are compared, and the positions of the data elements in each pair are selectively swapped based on a result of the respective comparison;
• in each second sorting cycle, the numerical values of pairs of data elements in a second set of adjacent positions are compared, the second set of adjacent positions being different from the first set of adjacent positions, and the positions of the data elements in each pair are selectively swapped based on a result of the respective comparison;
• and
• the N data elements are arranged into an ordered list which is ordered in order of their numerical values;
• either:
• output the data element, or the numerical value of the data element, in position (N+1)/2 if N is an odd number;
• or output an average of the numerical values of the data elements in positions N/2 and (N+1)/2 if N is an even number;
• or
• output an average of the numerical values of a group of data elements centred on a mid-point of the ordered list;
• and
• use the output as a median value of the N data elements.