Realizing increased sub-pixel spatial resolution in X-ray imaging using displaced multiple images

Thim, Jan; Norlin, Börje; O'Nils, Matthias; Abdalla, Suliman; Oelmann, Bengt

doi:10.1016/j.nima.2010.06.179

Cited by 5 publications

(5 citation statements)

References 3 publications

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“…Tests using the six different filters have been carried out on X-Ray test images of a characterization object, normally used to determine the resolution of an imaging system. The images were taken in a similar manner to that in [2]. In order to provide a measure in relation to the performance of the filters, the results are stated as the percentage of blurring noise still remaining in the image after filtering.…”

Section: Resultsmentioning

confidence: 99%

“…The performance difference for a spatial and a frequency domain filter of the same type were indistinguishable, so only one line is shown for each type of filter. Figure 4 also shows the raw performance of the oversampling technique, as presented in [2] (figure 4a), in order to provide a relationship between the before and after filtering performance. Here, the number of linepairs/mm seen in the sub-pixel image is divided by the theoretical linepairs/mm of a full resolution image with the same number of pixels as the sub-pixel image, to demonstrate a relative performance quality of the oversampling technique.…”

Section: Resultsmentioning

confidence: 99%

“…In these applications, alternative methods of utilizing the imaging system can be considered. One method of increasing spatial resolution that has previously been presented is the method of oversampling using displaced multiple images [2,3]. This method involves imaging an object with a number of images displaced from each other by sub-pixel distances.…”

Section: Introductionmentioning

confidence: 99%

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Suitable post processing algorithms for X-ray imaging using oversampled displaced multiple images

et al. 2011

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X-ray imaging systems such as photon counting pixel detectors have a limited spatial resolution of the pixels, based on the complexity and processing technology of the readout electronics. For X-ray imaging situations where the features of interest are smaller than the imaging system pixel size, and the pixel size cannot be made smaller in the hardware, alternative means of resolution enhancement require to be considered. Oversampling with the usage of multiple displaced images, where the pixels of all images are mapped to a final resolution enhanced image, has proven a viable method of reaching a sub-pixel resolution exceeding the original resolution. The effectiveness of the oversampling method declines with the number of images taken, the sub-pixel resolution increases, but relative to a real reduction of imaging pixel sizes yielding a full resolution image, the perceived resolution from the sub-pixel oversampled image is lower. This is because the oversampling method introduces blurring noise into the mapped final images, and the blurring relative to full resolution images increases with the oversampling factor. One way of increasing the performance of the oversampling method is by sharpening the images in post processing. This paper focus on characterizing the performance increase of the oversampling method after the use of some suitable post processing filters, for digital X-ray images specifically. The results show that spatial domain filters and frequency domain filters of the same type yield indistinguishable results, which is to be expected. The results also show that the effectiveness of applying sharpening filters to oversampled multiple images increase with the number of images used (oversampling factor), leaving 60-80% of the original blurring noise after filtering a 6 × 6 mapped image (36 images taken), where the percentage is depending on the type of filter. This means that the effectiveness of the oversampling itself increase by using sharpening filters, and more images taken can be considered worth the effort.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Suitable post processing algorithms for X-ray imaging using oversampled displaced multiple images

et al. 2011

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“…Previous attempts to obtain sub-pixel resolution in x-ray imaging utilizing photon-counting or integrating detectors yielded a much smaller increase in resolution with saturation at higher raster-scanning parameters. This stems mostly from the fact that previous investigations on this topic did not model the spatial detection system response and incorporate an appropriate deconvolution step [20,21]. Most detectors available so far have a much wider gaussian-shaped PSF arising from charge sharing in directly converting sensors or lateral propagation of light in scintillators.…”

Section: Discussionmentioning

confidence: 99%

X-ray deconvolution microscopy

Ehn

Epple

Fehringer

et al. 2016

Biomed. Opt. Express

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Recent advances in single-photon-counting detectors are enabling the development of novel approaches to reach micrometer-scale resolution in x-ray imaging. One example of such a technology are the MEDIPIX3RX-based detectors, such as the LAMBDA which can be operated with a small pixel size in combination with real-time on-chip charge-sharing correction. This characteristic results in a close to ideal, box-like point spread function which we made use of in this study. The proposed method is based on raster-scanning the sample with sub-pixel sized steps in front of the detector. Subsequently, a deconvolution algorithm is employed to compensate for blurring introduced by the overlap of pixels with a well defined point spread function during the raster-scanning. The presented approach utilizes standard laboratory x-ray equipment while we report resolutions close to 10 μm. The achieved resolution is shown to follow the relationship [Formula: see text] with the pixel-size p of the detector and the number of raster-scanning steps n.

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“…Bruandet & Dinten (1999) applied this method to the X-ray imaging field and improved the MTF of the imaging system (pixel size: 200 mm Â 200 mm). Thim et al (2011) increased the resolution to 1.8 times when using a single-photon processing system with pixel size of 220 mm Â 220 mm and micro-scanning step size of 1/4 pixel size. They increased the resolution to 1.67 times when using a single-photon processing system with pixel size of 55 mm Â 55 mm and micro-scanning step size of 1/3 pixel size.…”

Section: Introductionmentioning

confidence: 99%

Synchrotron radiation X-ray imaging with large field of view and high resolution using micro-scanning method

Sun¹,

Wang²,

Zhang³

et al. 2022

J Synchrotron Rad

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In synchrotron radiation X-ray imaging, the imaging field of view and spatial resolution are mutually restricted, which makes it impossible to have both a large field of view and high resolution when carrying out experiments. Constructing an oversampled image through the micro-scanning method and using the deconvolution algorithm to eliminate the point spread function introduced by pixel overlap can increase the resolution under a fixed imaging field of view, thereby improving the ratio of the field of view to the spatial resolution. In this paper, numerical simulation and synchrotron radiation experiments are carried out with a different number of micro-scanning steps. In numerical simulation experiments only affected by the image pixel size, as the number of micro-scanning steps increases, the ability of the oversampled image with deconvolution to improve the resolution is stronger. The achievable resolution of the oversampled image with deconvolution is basically the same as that of the sample image. In the synchrotron radiation experiments, the resolution of the oversampled image with deconvolution in the 2 × 2 mode is significantly improved. However, as the number of micro-scanning steps increases, the resolution improvement is limited, or even no longer improved. Finally, by analyzing the results of numerical simulation and synchrotron radiation experiments, three factors (four other factors affecting the resolution besides the camera resolution, translational accuracy of micro-scanning, and the signal-to-noise ratio of projections) affecting the micro-scanning method are proposed and verified by experiments.

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Realizing increased sub-pixel spatial resolution in X-ray imaging using displaced multiple images

Cited by 5 publications

References 3 publications

Suitable post processing algorithms for X-ray imaging using oversampled displaced multiple images

Suitable post processing algorithms for X-ray imaging using oversampled displaced multiple images

X-ray deconvolution microscopy

Synchrotron radiation X-ray imaging with large field of view and high resolution using micro-scanning method

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