Reduced television display flicker and perceived line structure with low horizontal scan rates

A method for deriving an interlaced television signal from an interlaced 625 line, nominally 50 Hz field rate television signal, the derived television signal having perceived reduced line structure and perceived reduced flicker, comprising,

• increasing the number of lines in each field of the derived television signal with respect to the number of lines in each field of the original television signal, such that the increase in lines reduces perceived line structure in the derived television signal, wherein said increasing the number of lines comprises
• increasing the number of lines in each frame of the original television signal, and
• de-interlacing the line-increased original television signal to produce a progressively scanned 625 line, nominally 50 Hz frame rate television signal, and
• after increasing the number of lines in each field, increasing the field rate of the derived television signal with respect to the field rate of the original television signal, such that the increase in field rate reduces perceived flicker in the derived television signal, wherein said increasing the field rate comprises
• reinterlacing the progressively scanned television signal such that for some progressively scanned frames a pair of interlaced fields are derived and for selected progressively scanned frames only one interlaced field is derived, whereby selected ones of the potential interlaced fields are dropped,
• wherein the increase in the field rate and the increase in the number of lines in the derived television signal results in a horizontal scanning rate that does not substantially exceed twice the horizontal scanning rate of the original television signal while minimizing undesirable motion artifacts.

A method for deriving an interlaced television signal from an interlaced 625 line, nominally 50 Hz field rate television signal, the derived television signal having perceived reduced line structure and perceived reduced flicker, comprising,

• increasing the field rate of the derived television signal with respect to the field rate of the original television signal, such that the increase in field rate reduces perceived flicker in the derived television signal, said increasing the field rate comprising
• deriving two or three signal streams from said original television signal, each of said signal streams comprising a pattern of n repeated time-compressed fields, each of said signal streams having a field rate substantially equal to said increased field rate, all of fields in a signal stream being of the same parity, at least one signal stream consisting of even parity fields, each field in a signal stream being substantially identical in information content to each consecutive field of the same parity in the original television signal,
• deriving a further signal stream from said two or three signal streams by alternately selecting even and odd fields from said two or three signal streams, and
• deriving yet a further signal stream from said two or three signal streams by alternately selecting, from said two or three signal streams, a field of opposite parity to the field selected for said further signal stream, and
• after increasing the field rate, increasing the number of lines in each field of the derived television signal with respect to the number of lines in each field of the original television signal, such that the increase in lines reduces perceived line structure in the derived television signal,
• wherein the increase in the field rate and the increase in the number of lines in the derived television signal results in a horizontal scanning rate that does not substantially exceed twice the horizontal scanning rate of the original television signal while minimizing undesirable motion artifacts.

A method for deriving an interlaced television signal from an interlaced 625 line, nominally 50 Hz field rate television signal, the derived television signal having perceived reduced line structure and perceived reduced flicker, comprising,

• increasing the field rate of the derived television signal with respect to the field rate of the original television signal, such that the increase in field rate reduces perceived flicker in the derived television signal, said increasing the field rate comprising
• deriving two or three signal streams from said original television signal, each of said signal streams comprising a pattern of n repeated time-compressed fields, each of said signal streams having a field rate substantially equal to said increased field rate, all of fields in a signal stream being of the same parity, at least one signal stream consisting of even parity fields, each field in a signal stream being substantially identical in information content to each consecutive field of the same parity in the original television signal,
• comparing two of said two or three signal streams in order to detect a film pattern,
• deriving a further signal stream from said two or three signal streams by alternately selecting even and odd fields from said two or three signal streams when a film pattern is detected, and
• deriving yet a further signal stream from said two or three signal streams by alternately selecting, from said two or three signal streams, a field of opposite parity to the field selected for said further signal stream when a film pattern is detected, and
• after increasing the field rate, increasing the number of lines in each field of the derived television signal with respect to the number of lines in each field of the original television signal, such that the increase in lines reduces perceived line structure in the derived television signal,
• wherein the increase in the field rate and the increase in the number of lines in the derived television signal results in a horizontal scanning rate that does not substantially exceed twice the horizontal scanning rate of the original television signal while minimizing undesirable motion artifacts.

A method for deriving an interlaced television signal from an interlaced 625 line, nominally 50 Hz field rate television signal, the derived television signal having perceived reduced line structure and perceived reduced flicker, comprising,

• increasing the field rate of the derived television signal with respect to the field rate of the original television signal, such that the increase in field rate reduces perceived flicker in the derived television signal, said increasing the field rate comprising
• deriving two or three signal streams from said original television signal, each of said signal streams comprising a pattern of n repeated time-compressed fields, each of said signal streams having a field rate substantially equal to said increased field rate, all of fields in a signal stream being of the same parity, at least one signal stream consisting of even parity fields, each field in a signal stream being substantially identical in information content to each consecutive field of the same parity in the original television signal,
• comparing adjacent fields in one of said two or three signal streams in order to detect motion,
• generating even and odd interpolated fields from fields in said two or three signal streams,
• deriving a further signal stream from said two or three signal streams and said interpolated fields by alternately selecting even and odd fields from among said two or three signal streams and interpolated fields when motion is detected, and
• deriving yet a further signal stream from said two or three signal streams and interpolated fields by alternately selecting, from said two or three signal streams and said interpolated fields, a field of opposite parity to the field selected for said further signal stream when motion is detected, and
• after increasing the field rate, increasing the number of lines in each field of the derived television signal with respect to the number of lines in each field of the original television signal, such that the increase in lines reduces perceived line structure in the derived television signal,
• wherein the increase in the field rate and the increase in the number of lines in the derived television signal results in a horizontal scanning rate that does not substantially exceed twice the horizontal scanning rate of the original television signal while minimizing undesirable motion.