Frame rate converting apparatus and method thereof
In an image processing apparatus, degradation of edges of stationary subjects can be suppressed in a moving image obtained by converting moving image data having F frames per unit time into moving image data having 2F sub frames per the unit time. For this purpose, pixel data is inputted in order of raster scanning into an input terminal. Then three contiguous pixel data X 1 to X 3 are obtained by the input terminal and two delay circuits. A differentiator calculates a difference d 1 (=X 1 −X 2 ) between the pixel data of interest X 2 and the neighbor pixel data X 1 and a difference d 2 (=X 3 −X 2 ) between the pixel data of interest X 2 and the neighbor pixel data X 3 . A multiplier coefficient for low-pass filter calculation is determined based on the differences d 1 and d 2 , and pixel data X 2 ′ is calculated as pixel data after filter-processing of the pixel data of interest X 2.
1. An image processing apparatus for converting moving image data having F frames per unit time into moving image data having 2F sub frames per the unit time, the apparatus comprising:
an input unit to input moving image data by frame;
a low-pass filter to multiply pixel data of interest and neighbor pixel data of the pixel data of interest in the frame inputted by said input unit by a multiplier coefficient and to add up the results of multiplication, thereby generating a low-frequency sub frame;
a high-frequency sub frame generator to extract high frequency component data from the frame inputted by said input unit and to add the high frequency component data to the frame inputted by said input unit, thereby generating a high-frequency sub frame; and
an output unit to output the low-frequency sub frame and the high-frequency sub frame,
wherein said low-pass filter comprises:
(a) a subtracter to subtract a brightness value of the pixel data of interest from a brightness value of the neighbor pixel data;
(b) a comparator to compare a result d 1 of subtraction by said subtracter with a previously-set threshold Th equal to or greater than 0; and
(c) a selector to, (1) when d 1 ≦Th holds as the result of comparison by said comparator, select a previously-set positive multiplier coefficient V 0 as a multiplier coefficient for multiplication of the neighbor pixel data, and (2) while when d 1 >Th holds as the result of comparison by said comparator, select a positive multiplier coefficient V 1 less than the multiplier coefficient V 0 as the multiplier coefficient for multiplication of the neighbor pixel data,
wherein the apparatus further comprises a multiplier to multiply the low-frequency sub frame generated by said low-pass filter by a positive multiplier coefficient less than 1, and to output the result of multiplication as a subject of selection by said output unit, and
wherein said high-frequency sub frame generator subtracts the result of multiplication by said multiplier from the frame inputted by said input unit, thereby generating the high-frequency sub frame.
2. An image processing apparatus for converting moving image data having F frames per unit time into moving image data having 2F sub frames per the unit time, the apparatus comprising:
an input unit to input moving image data by frame;
a low-pass filter to multiply pixel data of interest and neighbor pixel data of the pixel data of interest in the frame inputted by said input unit by a multiplier coefficient and to add up the result of multiplication, thereby generating a low-frequency sub frame;
a high-frequency sub frame generator to extract high frequency component data from the frame inputted by said input unit and to add the high frequency component data to the frame inputted by said input unit, thereby generating a high-frequency sub frame; and
an output unit to output the low-frequency sub frame and the high-frequency sub frame,
wherein said low-pass filter comprises:
(a) a subtracter to subtract a brightness value of the pixel data of interest from a brightness value of the neighbor pixel data;
(b) a comparator to compare a result d 1 of subtraction by said subtracter with a previously-set threshold Th equal to or greater than 0; and
(c) a processor to, (1) when d 1 ≦Th holds as the result of comparison by said comparator, perform low-pass filter processing on the pixel data of interest using the pixel data of interest and the neighbor pixel data, and (2) while when d 1 >Th holds as the result of comparison by said comparator, performing the low-pass filter processing on the pixel data of interest using the pixel data of interest and the pixel data of interest as substitute data for the neighbor pixel data,
wherein the apparatus further comprises a multiplier to multiply the low-frequency sub frame generated by said low-pass filter by a positive multiplier coefficient less than 1, and to output the result of multiplication as a subject of selection by said output unit, and
wherein said high-frequency sub frame generator subtracts the result of multiplication by said multiplier from the frame inputted by said input unit, thereby generating the high-frequency sub frame.
3. A control method for an image processing apparatus for converting moving image data having F frames per unit time into moving image data having 2F sub frames per the unit time, the method comprising:
an input step of inputting moving image data by frame;
a low-pass filter step of multiplying pixel data of interest and neighbor pixel data of the pixel data of interest in the frame inputted at said input step by a multiplier coefficient and adding up the results of multiplication, thereby generating a low-frequency sub frame;
a high-frequency sub frame generation step of extracting high frequency component data from the frame inputted at said input step and adding the high frequency component data to the frame inputted at said input step, thereby generating a high-frequency sub frame; and
an output step of outputting the low-frequency sub frame and the high-frequency sub frame,
wherein said low-pass filter step comprises:
(a) a subtraction step of subtracting a brightness value of the pixel data of interest from a brightness value of the neighbor pixel data;
(b) a comparison step of comparing a result d 1 of subtraction at said subtraction step with a previously-set threshold Th equal to or greater than 0; and
(c) a selection step of, (1) when d 1 ≦Th holds as the result of comparison at said comparison step, selecting a previously-set positive multiplier coefficient V 0 as a multiplier coefficient for multiplication of the neighbor pixel data, and (2) while when d 1 >Th holds as the result of comparison at said comparison step, selecting a positive multiplier coefficient V 1 less than the multiplier coefficient V 0 as the multiplier coefficient for multiplication of the neighbor pixel data,
wherein the method further comprises a multiplication step of multiplying the low-frequency sub frame generated by said low-pass filter step by a positive multiplier coefficient less than 1, and outputting the result of multiplication as a subject of selection by said output step, and
wherein said high-frequency sub frame generation step subtracts the result of multiplication by said multiplication step from the frame inputted by said input step, thereby generating the high-frequency sub frame.
4. A control method for an image processing apparatus for converting moving image data having F frames per unit time into moving image data having 2F sub frames per the unit time, the method comprising:
an input step of inputting moving image data by frame;
a low-pass filter step of multiplying pixel data of interest and neighbor pixel data of the pixel data of interest in the frame inputted at said input step by a multiplier coefficient and adding up the results of multiplication, thereby generating a low-frequency sub frame;
a high-frequency sub frame generation step of extracting high frequency component data from the frame inputted at said input step and adding the high frequency component data to the frame inputted at said input step, thereby generating a high-frequency sub frame; and
an output step of outputting the low-frequency sub frame and the high-frequency sub frame,
wherein said low-pass filter step comprises:
(a) a subtraction step of subtracting a brightness value of the pixel data of interest from a brightness value of the neighbor pixel data;
(b) a comparison step of comparing a result d 1 of subtraction at said subtraction step with a previously-set threshold Th equal to or greater than 0; and
(c) processing step of, (1) when d 1 ≦Th holds as the result of comparison at said comparison step, performing low-pass filter processing on the pixel data of interest using the pixel data of interest and the neighbor pixel data, and (2) while when d 1 >Th holds as the result of comparison at said comparison step, performing the low-pass filter processing on the pixel data of interest using the pixel data of interest and the pixel data of interest as substitute data for the neighbor pixel data,
wherein the method further comprises a multiplication step of multiplying the low-frequency sub frame generated by said low-pass filter step by a positive multiplier coefficient less than 1, and outputting the result of multiplication as a subject of selection by said output step,
wherein said high-frequency sub frame generation step subtracts the result of multiplication by said multiplication step from the frame inputted by said input step, thereby generating the high-frequency sub frame.
5. A non-transitory computer-readable storage medium holding a computer program read and executed by a computer, thereby causing the computer to function as the image processing apparatus recited in claim 1 .
6. A non-transitory computer-readable storage medium holding a computer program read and executed by a computer, thereby causing the computer to function as the image processing apparatus recited in claim 2 .