Picture quality improvement device and picture quality improvement method
A field delay circuit aligns the phases of two field signals. An average value calculation circuit generates an average value signal of the two field signals. This average value signal can be regarded as a signal that has undergone a one-dimensional low-pass filter process in the row direction in which the number of taps for a progressive signal is 2 and the filter coefficient for each tap is 0.5 and that has then been thinned to one-half the data. A two-dimensional LPF circuit subjects this average value signal to a low-pass filter process and eliminates the high-frequency components (edge components). A subtraction circuit subtracts the average value signal that has undergone the LPF process from each field signal and thus extracts the edge components of each field signal. An amplification circuit multiplies the edge components of each field signal by a prescribed factor. An addition circuit adds the resulting amplified edge components to each field signal.
1. A picture quality improvement device, said picture quality improvement device receiving as input an interlaced signal in which data of picture elements of adjacent rows are distributed between two field signals that are separated by time and transmitted, and emphasizing edges in a video image at a sampling clock frequency of said interlaced signal; said picture quality improvement device comprising:
a first means for aligning phases of the two field signals that have been received as input;
a second means for finding each of average values of data of the same order in data strings of the two field signals for which phases have been aligned by said first means and generating an average value signal having these average values as a data string;
a third means for subjecting said average value signal to a two-dimensional low-pass filter process and eliminating frequency components having frequencies that are higher than a prescribed frequency;
a fourth means for subtracting, from the data strings of said two field signals that have been received as input, the data string of said average value signal in which high-frequency components have been eliminated and that has been generated by said third means, and generating signals in which the high-frequency components have been extracted for each of the field signals;
a fifth means for multiplying, by a prescribed factor, the signals in which high-frequency components have been extracted of each field signal that have been generated by said fourth means; and
a sixth means for adding, to the data strings of said two field signals that have been received as input, the data strings of the signals in which high-frequency components have been extracted of each field signal and that have been multiplied by the prescribed factor by said fifth means.
2. A picture quality improvement device according to claim 1 , wherein said interlaced signal is a luminance signal of a luminance/color difference signal.
3. A picture quality improvement device, said picture quality improvement device receiving as input an interlaced signal in which data of picture elements of adjacent rows are distributed between two field signals that are separated by time and transmitted, and emphasizing edges in a video image at a sampling clock frequency of said interlaced signal; said picture quality improvement device comprising:
a field delay circuit for aligning phases of the two field signals that have been received as input;
an average value calculation circuit for finding each of average values of data of the same order in data strings of the two field signals for which phases have been aligned by said field delay circuit and generating an average value signal having these average values as a data string;
a two-dimensional low-pass filter circuit for subjecting said average value signal to a two-dimensional low-pass filter process and eliminating frequency components having frequencies that are higher than a prescribed frequency;
a subtraction circuit for subtracting, from the data strings of said two field signals that have been received as input, the data string of said average value signal in which high-frequency components have been eliminated and that has been generated by said two-dimensional low-pass filter circuit, and generating signals in which the high-frequency components have been extracted for each of the field signals;
an amplification circuit for multiplying, by a prescribed factor, the signals in which high frequency components have been extracted of each field signal that have been generated by said subtraction circuit; and
an addition circuit for adding, to the data strings of said two field signals that have been received as input, the data strings of the signals in which high-frequency components have been extracted of each field signal and that have been multiplied by the prescribed factor by said amplification circuit.
4. A picture quality improvement device according to claim 3 , wherein said interlaced signal is a luminance signal of a luminance/color difference signal.
5. A picture quality improvement method, in which an interlaced signal is received as input in which data of picture elements of adjacent rows are distributed between two field signals that are separated by time and transmitted, and in which edges in a video image are emphasized at a sampling clock frequency of said interlaced signal; said picture quality improvement method comprising:
a first step of aligning phases of the two field signals that have been received as input;
a second step of finding each of average values of data of the same order in data strings of the two field signals for which phases have been aligned in said first step and generating an average value signal having these average values as a data string;
a third step of subjecting said average value signal to a two-dimensional low-pass filter process and eliminating frequency components having frequencies that are higher than a prescribed frequency;
a fourth step of subtracting, from the data strings of said two field signals that have been received as input, the data string of said average value signal in which high-frequency components have been eliminated and that has been generated by said third means, and generating signals in which the high-frequency components have been extracted for each of the field signals;
a fifth step of multiplying, by a prescribed factor, the signals in which high-frequency components have been extracted of each field signal that have been generated in said fourth step; and
a sixth step of adding, to the data strings of said two field signals that have been received as input, the data strings of the signals in which high-frequency components have been extracted of each field signal and that have been multiplied by the prescribed factor in said fifth step.
6. A picture quality improvement method according to claim 5 , wherein said interlaced signal is a luminance signal of a luminance/color difference signal.