Wavelet denoising of fringe image

An image processing method for processing a fringe pattern captured by an X-Ray Talbot interferometer, the method comprising:

• capturing a fringe pattern of an object being imaged by the X-Ray Talbot interferometer, the fringe pattern being modulated in accordance with a modulation strength introduced by the object;
• determining a carrier frequency component associated with the captured fringe pattern, wherein the carrier frequency component is dependent on at least one grating used in the X-Ray Talbot interferometer;
• obtaining wavelet coefficients for the captured fringe pattern by applying a wavelet transform to the captured fringe pattern;
• establishing a wavelet coefficients mapping function that varies depending on the carrier frequency component of the captured fringe pattern and the modulation strength introduced by the object;
• transforming the obtained wavelet coefficients using the established wavelet coefficients mapping function;
• de-noising the captured fringe pattern by applying inverse wavelet transform to the transformed wavelet coefficients to form a denoised fringe pattern;
• and
• demodulating the de-noised fringe pattern to determine object phase data associated with the optical path length of the object.

An image de-noising method for de-noising a fringe pattern captured by an X-Ray Talbot interferometer, the method comprising:

• capturing a fringe pattern from the X-Ray Talbot interferometer, the captured fringe pattern having a carrier frequency component dependent on settings of the X-Ray Talbot interferometer;
• obtaining wavelet coefficients for the captured fringe pattern by applying a wavelet transform to the captured fringe pattern;
• suppressing the obtained wavelet coefficients in accordance with the carrier frequency component of the captured fringe pattern, wherein the suppressing rate increases with increasing the carrier frequency of the captured fringe pattern;
• and
• de-noising the captured fringe pattern by applying inverse wavelet transform to the suppressed wavelet coefficients to form denoised fringe pattern.

A computer readable storage medium having a program recorded thereon, the program being executable by computer apparatus to process an image, the program comprising:

• code for capturing a fringe pattern from an energy source, the captured fringe pattern having a carrier frequency component dependent on settings of the energy source;
• code for obtaining wavelet coefficients for the captured fringe pattern by applying a wavelet transform to the captured fringe pattern;
• code for establishing a wavelet coefficients mapping function having a rate of change that varies depending at least on the carrier frequency component of the captured fringe pattern;
• code for transforming the obtained wavelet coefficients using the established wavelet coefficients mapping function;
• and
• code for processing the captured fringe pattern by applying inverse wavelet transform to the transformed wavelet coefficients to form a denoised fringe pattern.

An X-ray Talbot imaging system comprising:

• imaging apparatus for capturing a fringe pattern from an energy source, the captured fringe pattern having a carrier frequency component dependent on settings of the energy source;
• a computing apparatus configured to:
• obtain wavelet coefficients for the captured fringe pattern by applying a wavelet transform to the captured fringe pattern;
• establish a wavelet coefficients mapping function having a rate of change that varies depending at least on the carrier frequency component of the captured fringe pattern;
• transform the obtained wavelet coefficients using the established wavelet coefficients mapping function;
• and
• process the captured fringe pattern by applying inverse wavelet transform to the transformed wavelet coefficients to form a denoised fringe pattern;
• and
• a tangible memory configured to at least store the denoised fringe pattern.

A computer readable storage medium having a program recorded thereon, the program being executable by computer apparatus to process an image, the program comprising:

• code for capturing a fringe pattern from an energy source, the captured fringe pattern having a carrier frequency component dependent on settings of the energy source;
• code for obtaining wavelet coefficients for the captured fringe pattern by applying a wavelet transform to the captured fringe pattern;
• code for establishing a wavelet coefficients mapping function that varies depending on the carrier frequency component of the captured fringe pattern;
• code for transforming the obtained wavelet coefficients using the established wavelet coefficients mapping function;
• and
• code for processing the captured fringe pattern by applying inverse wavelet transform to the transformed wavelet coefficients to form a denoised fringe pattern.

A computer readable storage medium having a program recorded thereon, the program being executable by computer apparatus to process an image, the program comprising:

• code for capturing a fringe pattern from an energy source, the captured fringe pattern having a carrier frequency component dependent on settings of the energy source;
• code for obtaining wavelet coefficients for the captured fringe pattern by applying a wavelet transform to the captured fringe pattern;
• code for suppressing the obtained wavelet coefficients in accordance with the carrier frequency component of the captured fringe pattern, wherein the suppressing rate increases with increasing the carrier frequency of the captured fringe pattern;
• and
• code for processing the captured fringe pattern by applying inverse wavelet transform to the suppressed wavelet coefficients to form denoised fringe pattern.