Method of coding a digital signal, method of generating a coding table, coding apparatus and coding method

A coding apparatus for generating coding tables, comprising:

• converting means for converting an orthogonally transformed digital signal into a data series formed of consecutive zero coefficients and non-zero coefficients;
• classifying means for classifying each of said non-zero coefficients into a size grouping based on the value of said non-zero coefficient;
• and
• generating means for generating a plurality of tables, one for each of said size groupings, based on an occurrence frequency of a next size grouping following a preceding size grouping, wherein said table includes a variable length code word for each of said next size groupings, the length of each said code words being dependent upon a correlation between said preceding size grouping and said next size grouping.

A coding method for coding a digital signal, comprising the steps of:

• converting said digital signal into a data series formed of consecutive zero coefficients and non-zero coefficients;
• classifying each of said non-zero coefficients into a size grouping based on the value of said non-zero coefficient;
• and
• coding a next size grouping by using a code word selected from one of a plurality of tables of data, each table corresponding to a preceding size grouping and including code words of variable length for each respective next size grouping, wherein the length of each of said code words varies depending upon a correlation between said preceding size grouping and said next size grouping, said code word is selected for said next size grouping based on the table corresponding to said preceding size grouping.

A coding method for generating coding tables, comprising the steps of:

• converting a digital signal into a data series formed of zero coefficients and non-zero coefficients;
• classifying each of said non-zero coefficients into a size grouping based on the value of said non-zero coefficient;
• and
• generating a plurality of tables, one for each of said size groupings, based on an occurrence frequency of a next size grouping following a preceding size grouping, wherein said table includes a variable length code word for each of said next size groupings, the length of each said code words being dependent upon a correlation between said preceding size grouping and said next size grouping.