Signal processing apparatus and method, recording medium, and program
View Patent ↗An n-filter according to the present invention includes a nonlinear filter, a pattern detector, and a switch. The nonlinear filter maintains a steep edge whose size is larger than a predetermined threshold in fluctuations of pixels constituting an input image signal and, at the same time, smoothes a non-edge portion that does not include the edge. The pattern detector detects a fine edge in the fluctuations of the pixels constituting the input image signal and notifies the switch that the fine edge exists. The switch outputs the input image signal or an image signal output from the nonlinear filter to the subsequent stage in accordance with the notification from the pattern detector.
1. A signal processing apparatus for adjusting levels of signals arranged consecutively, the apparatus comprising:
first designating means for sequentially designating each of said signals as a target signal;
second designating means for designating a plurality of neighboring signals from among said signals on the basis of the target signal designated by the first designating means;
calculating means for calculating differences between the target signal and the plurality of neighboring signals and for calculating a smoothing signal by obtaining a weighted average of the target signal and the plurality of neighboring signals in accordance with results of comparison between the differences and a first threshold;
determining means for calculating the differences between the target signal and the plurality of neighboring signals and for determining whether or not a fine edge exists near the target signal in accordance with results of comparison between the differences and a second threshold, which is smaller than the first threshold; and
selecting means for selecting one of the smoothing signal and the target signal in accordance with a result determined by the determining means.
2. The signal processing apparatus according to claim 1 , wherein said signals are pixel values of pixels constituting an image.
3. A signal processing method for adjusting levels of signals arranged consecutively, the method comprising:
a first designating step of sequentially designating each of said signals as a target signal;
a second designating step of designating a plurality of neighboring signals from among said signals on the basis of the target signal designated by the first designating step;
a calculating step of calculating differences between the target signal and the plurality of neighboring signals and of calculating a smoothing signal by obtaining a weighted average of the target signal and the plurality of neighboring signals in accordance with results of comparison between the differences and a first threshold;
a determining step of calculating the differences between the target signal and the plurality of neighboring signals and of determining whether or not a fine edge exists near the target signal in accordance with results of comparison between the differences and a second threshold, which is smaller than the first threshold; and
a selecting step of selecting one of the smoothing signal and the target signal in accordance with a result determined by the determining step.
4. A recording medium recording therein a computer-readable program for adjusting levels of signals arranged consecutively, the program comprising:
a first designating step of sequentially designating each of said signals as a target signal;
a second designating step of designating a plurality of neighboring signals from among said signals on the basis of the target signal designated by the first designating step;
a calculating step of calculating differences between the target signal and the plurality of neighboring signals and of calculating a smoothing signal by obtaining a weighted average of the target signal and the plurality of neighboring signals in accordance with results of comparison between the differences and a first threshold;
a determining step of calculating the differences between the target signal and the plurality of neighboring signals and of determining whether or not a fine edge exists near the target signal in accordance with results of comparison between the differences and a second threshold, which is smaller than the first threshold; and
a selecting step of selecting one of the smoothing signal and the target signal in accordance with a result determined by the determining step.
5. A program for adjusting levels of signals arranged consecutively, the program causing a computer to perform a process comprising:
a first designating step of sequentially designating each of said signals as a target signal;
a second designating step of designating a plurality of neighboring signals from among said signals on the basis of the target signal designated by the first designating step;
a calculating step of calculating differences between the target signal and the plurality of neighboring signals and of calculating a smoothing signal by obtaining a weighted average of the target signal and the plurality of neighboring signals in accordance with results of comparison between the differences and a first threshold;
a determining step of calculating the differences between the target signal and the plurality of neighboring signals and of determining whether or not a fine edge exists near the target signal in accordance with results of comparison between the differences and a second threshold, which is smaller than the first threshold; and
a selecting step of selecting one of the smoothing signal and the target signal in accordance with a result determined by the determining step.