Comparison of SAFT and two-dimensional deconvolution methods for the improvement of resolution in ultrasonic B-scan images

This Paper compares the properties of the well known synthetic aperture focusing technique (SAFT) with those of two deconvolution methods, which have previously been less widely applied to digitized ultrasonic data. The linear deconvolution method of Wiener filtering and the non-linear maximum entro...

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Bibliographic Details
Published inUltrasonics Vol. 25; no. 5; pp. 259 - 266
Main Author Burch, S.F.
Format Journal Article
LanguageEnglish
Published Amsterdam Elsevier B.V 01.09.1987
Elsevier Science
Subjects
Acoustics
B-scan
deconvolution
Exact sciences and technology
Fundamental areas of phenomenology (including applications)
image resolution
Physics
SAFT
Ultrasonics, quantum acoustics, and physical effects of sound
deconvolution
SAFT
image resolution
B-scan
Image quality
Resolving power
Improvement
Deconvolution
Image processing
Ultrasound imaging
Synthetic aperture
Focusing
B mode sonography
Digital processing
Digital image
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Summary:This Paper compares the properties of the well known synthetic aperture focusing technique (SAFT) with those of two deconvolution methods, which have previously been less widely applied to digitized ultrasonic data. The linear deconvolution method of Wiener filtering and the non-linear maximum entropy method are applied to two-dimensional unrectified (RF) B-scan data, to improve the resolution simultaneously in the lateral and range directions. With SAFT, only an improvement in lateral resolution is possible. Data from linear scans of several unfocussed transducers over machined reflectors at different depths in steel were collected and used to quantify the resolution obtainable by the three processing methods. Wiener filtering is shown to give higher lateral resolution than SAFT processing, by factors of between 1.3 and 2, depending on the depth of the reflector. Maximum entropy gives even higher apparent lateral resolution, but has a tendency to underestimate reflector size. The improvement in range resolution obtainable with Wiener filtering was approximately a factor of 1.5, whereas maximum entropy gave corresponding factors of between 1.7 and 5. For far-field reflectors, deconvolution of rectified (envelope-detected) data is shown to give inherently lower lateral resolution than the deconvolution of the equivalent RF data.
ISSN:0041-624X
1874-9968
DOI:10.1016/0041-624X(87)90047-3