FreqDIBWiener  Method

Description         This function will Wiener filter the input DIB by the degradation function DIB in the frequency domain. It works with 4, 8 or 24 bits/pixel images. Inverse filtering of an image is processed by dividing the input image by the degradation function image to obtain the original noiseless image. The noise must be characterizable by a Fourier spectrum (typically linear motion blur). The input is the degraded image and the image of the degradation function. The filter will first process the spectras of both images, after computing a complex division using the transformed images by the following equation:

, where G(u,v) is the degraded spectrum, H(u,v) is the degradation function spectrum, and * means complex conjugation. Finally the filtering returns with the inverse transformed, filtered image. The degradation spectra is multiplied by the SpectMul parameter, so normalization problems can be solved by tuning this parameter. In case of 4 or 8 bits/pixel, the source DIB must contain grayscale images and the palette values in the source DIB must be monotone increasing. It makes no sense to use this function in case of 1 bits/pixel. If the source DIB size is not power of two, zero padding is used.

Examples

Description: oszlopontoszblurredDescription: oszlopontoszfilteredDescription: oszlopontoszrefiltered

Syntax                 lRet = [BIFilter.]FreqDIBWiener SrcDib DFDib NSR bFFTMethod SpectMul

Remarks             lRet                         LONGLONG Handle of the newly created DIB on success or 0 on failure.

                            SrcDib                    LONGLONG Source DIB.

                            NSR                        Long                Inverse of the Signal-Noise Ratio.

                            DFDib                    Long                Degradation function DIB.

                            bFFTMethod         BOOL             Fast Fourier Transform method

                            SpectMul                Long                Degradation function multiplying factor

 

bFFTMethod
If bFFTMethod = TRUE, then the Fourier transformed of the image will be processed by Sin and Cos functions, if bFFTMethod = FALSE, then it will be processed by square root functions.

NSR
The inverse of the Signal-Noise Ratio. If NSR parameter is zero, the wiener filter reduces to the inverse filter.

See Also