Method and apparatus for increasing the resolution of a data sequence
View Patent ↗The invention relates to a method and an apparatus for increasing the resolution of a data sequence, such as for example a video data sequence. Between two data values of a given data sequence at least one intermediate value is interpolated by applying low-pass filtering and at least one first and one second high-pass filterings to data values of the data sequence, subjecting the filter values obtained by the high-pass filterings to rank-order filtering and combining the filter result so obtained with the filter result obtained by low-pass filtering.
1. A method for generating, from a first data sequence of video data having a sequence of data values, a second data sequence of video data having a higher resolution than the first data sequence, the method comprising:
generating an intermediate sequence from the first data sequence (a′[k]) by inserting at least one specified intermediate value between every two consecutive data values of the first data sequence (a′[k]);
filtering the intermediate sequence (a[k]) to generate the second data sequence, this filtering exhibiting the following procedural steps in order to generate a data value (s[i]) of the second data sequence (s[k]), where the filtering comprises
low-pass filtering at least two data values (a[i−1], a[i], a[i+1]) of the intermediate sequence (a[k]), at least one of which (a[i+1]) comes before a given data value (a[i]) in the intermediate sequence (a[k]) and at least one of which (a[i−1]) comes after the given data value in the intermediate sequence (a[k]), in order to prepare a low-pass filter value (tp[i]);
first high-pass filtering of at least two data values (a[i−1], (a[i−3]) of the intermediate sequence that come before the given data value in the intermediate sequence (a[k]) in order to prepare at least one first high-pass filter value (hp 1 [i]);
second high-pass filtering of at least two data values (a[i+1], (a[i+3]) of the intermediate sequence that come after the given data value in the intermediate sequence (a[k]) to prepare at least one second high-pass filter value (hp 2 [i]);
rank-order filtering at least to the at least one first high-pass filter value (hp 1 [i]) and the at least one second high-pass filter value (hp 2 [i]) to prepare a rank-order filter value (hp[i]); and
combining the low-pass filter value (tp[i]) and the rank-order filter value to prepare the data value (s[i]) of the second data sequence, of higher resolution video data in comparison to the first data sequence.
2. The method of claim 1 , where rank-order filtering is applied to the at least one first high-pass filter value (hp 1 [i]), the at least one second high-pass filter value (hp 2 [i]) and a specified constant value.
3. The method of claim 2 , where the constant value is zero.
4. The method of claim 1 , where the rank-order filtering is a median filtering.
5. The method of claim 1 , where the at least two data values that are low pass filtered in step a) comprise the given data value.
6. The method of claim 1 , where at least two first high-pass filterings and at least two second high-pass filterings are performed.
7. The method of claim 1 , where the step of combining comprises summing the low-pass filter value and the rank order filter value.
8. The method of claim 1 , where the procedural steps a) to e) are performed for all consecutive data values of the intermediate sequence (a[k]).
9. A filter configuration for filtering a video data sequence (a[k]), comprising:
a memory for storing a first data value (a[i]) of the data sequence, for storing a first group having at least two data values (a[i+1], a[i+2], a[i+3]) that come before the first data value (a[i]) in the data sequence (a[k]) and for storing a second group of at least two data values (a[i−1], a[i−2], a[i−3]) that come after the first data value (a[i]) in the data sequence (a[k]);
a low-pass filter that receives at least one data value of the first group and at least one data value of the second group and provides a low-pass filter value (tp[i]);
at least one first high-pass filter that receives at least two data values of the first group and provides at least one first high-pass filter value (hp 1 [i]);
at least one second high-pass filter that receives at least two data values of the second group and provides at least one second high-pass filter value (hp 2 [i]);
a rank-order filter that receives the at least one first high-pass filter value (hp 1 [i]) and the at least one second high-pass filter value (hp 2 [i]) and provides a rank-order filter value in dependence on these filter values; and
a combining unit that combines the rank-order filter value (hp[i]) with the low-pass filter value to provide an output video value (s[k]).
10. The filter configuration of claim 9 , where the low-pass filter is supplied with the given data value.
11. The filter configuration of claim 9 , where the rank-order filter receives a constant data value in addition to the at least one first high-pass filter value (hp 1 [i]) and the at least one second high-pass filter value (hp 2 [i]).