Sharpness enhancement
View Patent ↗In a method of sharpness enhancement, an input signal (s) is filtered (HLHP, VLHP) to obtain a filtered signal (z x , z y ), the filtered signal is multiplied (M 2 , M 3 ) by a controllable fraction (c x , c y ) to obtain multiplied signals, and the multiplied signals are added (A 2 ) to the input signal (s). The controllable fraction (c x , c y ) is generated by a non-linear function (HCF, VCF).
1. A method of sharpness enhancement, the method comprising the steps:
filtering an input signal to form a filtered signal;
multiplying the filtered signal by a controllable fraction to form a multiplied signal; and
adding the multiplied signal to the input signal;
wherein the controllable fraction depends on a non-linear function,
and wherein the filtering is a spatial filtering, and the method further comprises the steps:
temporally filtering the input signal to form a temporally filtered signal; and
adding the temporally filtered signal to the input signal.
2. The method as claimed in claim 1 , wherein the controllable fraction depends on an edge sensing function.
3. The method as claimed in claim 2 , wherein the controllable fraction is smaller than its maximum value for edges smaller than a first threshold value.
4. The method as claimed in claim 2 , wherein the controllable fraction is smaller than its maximum value for edges exceeding a second threshold value.
5. The method as claimed in claim 1 , wherein the non-linear function depends on a thin line detection.
6. The method as claimed in claim 5 , wherein the thin line detection is carried out on the filtered signal.
7. The method as claimed in claim 2 , wherein the edge sensing function is variance-based.
8. The method as claimed in claim 7 , wherein the controllable fraction is negative for signal variations smaller than a certain threshold.
9. A method of sharpness enhancement, the method comprising the steps:
filtering an input signal to form a filtered signal;
multiplying the filtered signal by a controllable fraction to form a multiplied signal; and
adding the multiplied signal to the input signal;
wherein the controllable fraction depends on a non-linear function,
and wherein the method further comprises the steps:
detecting a blocking and/or ringing effect including comparing mean values of adjacent pixel windows; and
detecting a block size based on an autocorrelation of a vector indicating blocking and/or ringing effects.
10. The method as claimed in claim 9 , wherein the blocking and/or ringing effect detecting step further includes comparing variances of the adjacent pixel windows to a threshold value.
11. A device for sharpness enhancement, the device comprising:
means for spatially filtering an input signal to form a filtered signal;
means for multiplying the filtered signal by a controllable fraction to form a multiplied signal;
means for adding the multiplied signal to the input signal;
means for generating the controllable fraction using a non-linear functions;
means for temporally filtering the input signal to form a temporally filtered signal; and
means for adding the temporally filtered signal to the input signal.
12. A television apparatus, comprising:
a device for sharpness enhancement as claimed in claim 11 ; and
means for displaying the sharpened signal.