A Robust Point Spread Function Estimation for Out-of-Focus Blurred and Noisy Images Based on a Distribution of Gradient Vectors on the Polar Plane

Sakano, Morihiko; Suetake, Noriaki; Uchino, Eiji

doi:10.1007/s10043-007-0297-5

Cited by 17 publications

(13 citation statements)

References 9 publications

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“…Therefore, their algorithm cannot be applied to a real time diagnostic. Sakano's and Oyamada's methods [6], [7] restore the deteriorated images accurately, and the computational costs are low, but their methods cannot estimate both the defocus and the motion blur PSF.…”

Section: Problems In Previous Methodsmentioning

confidence: 99%

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The development of an all-in-focus algorithm for endoscopy

Koseki

Ohara

Kamiyama

et al. 2013

Mhs2013

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Generally, the operation of an endoscope requires a skillful operator, due to the difficulty of focusing on the target region. To support such a task, a vision system that can produce clear endoscopic images to easily understand the target region, is required. In this paper, we propose an all-in-focus image creation algorithm which uses the original one, developed for microscopic image, and assuming that the target area is static, but we extend its application to endoscopic images. Through several experiments, we confirm the effectiveness of our proposed algorithm.

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Section: Problems In Previous Methodsmentioning

confidence: 99%

“…Sakano et al [6] proposed an algorithm which estimates the PSF caused by the defocus. They focused on the dark rings appearing in the frequency of the defocused images, and estimated the defocus PSF.…”

Section: All-in-focus Image Creation Algorithm Based On Psf Estimationmentioning

confidence: 99%

The development of an all-in-focus algorithm for endoscopy

Koseki

Ohara

Kamiyama

et al. 2013

Mhs2013

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“…Generally speaking, if a CCD camera sensor is off the focal plane of an optical system, one can only obtain defocused images with blurred edges. In the frequency domain, this means that the high-frequency components of an image with distinct edges are filtered out due to the low-frequency pass characteristics of the system [18]. To capture a clear image, the basic idea of the AFT is to adjust the lens of the optical system to a proper position so that the CCD camera sensor is well positioned at the focal plane, and abundant high-frequency (HF) components are then obtained to provide a distinct boundary contour of the image.…”

Section: Auto-focus Experiments Setmentioning

confidence: 99%

Accurate and Rapid Auto-Focus Methods Based on Image Quality Assessment for Telescope Observation

Yang

Chen

Zhou³

et al. 2020

Applied Sciences

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Aiming at improving the speed and accuracy of auto-focus for telescope observation, algorithms for image estimation and auto-focus were investigated and are discussed in this article. Based on the image quality assessment, the auto-focusing process of the telescope system is realized by using the mountain-climb search method. Several evaluation functions were tested in different scenarios. It is demonstrated that the Tenengrad image estimation function (IEF) is suitable for an instant and accurate auto-focus process of the telescope. Furthermore, we implemented sampling and dynamic adaptive focusing window (ES-DAFW) methods with the Tenengrad IEF to enhance the sensitivity and accuracy of the auto-focus process. The experimental results showed that our ES-DATW method can provide more accurate results in less time for the auto-focus process compared to the conventional approaches, especially for a sparse image. These results promise significant applications to the auto-focusing of other telescopes with image quality assessment.

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“…As this plane can have a large distance to the paraxial focus plane we only consider IPSF models suitable for large defocus distances. Common out-of-focus IPSF models are based on the approximation of the circle of confusion with a round disc of homogeneous intensity [34][35][36][37][38][39] or on a wave optical analysis [3,4,22,[34][35][36][37]40] that takes diffraction effects into account. Alternatively, the IPSF is approximated by a normal distribution [38,41].…”

Section: Calculation Of the Intensity Point Spread Function At An Outmentioning

confidence: 99%

Spectral characteristics of chromatic confocal imaging systems

et al. 2014

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We present signal-generation models for chromatic confocal imaging systems with illumination and detection pinholes of finite size: a collinear model that considers neither aberrations nor diffraction effects, a geometrical model that accounts for aberrations, and a wave optical model covering both aberrations and diffraction effects. These models are aimed at describing the spectral response of multipoint sensor systems with field-dependent aberrations and vignetting effects. They are suitable for single- and double-pass systems with either diffusely or specularly reflecting surfaces under test. We show experimental results to verify our models.

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A Robust Point Spread Function Estimation for Out-of-Focus Blurred and Noisy Images Based on a Distribution of Gradient Vectors on the Polar Plane

Cited by 17 publications

References 9 publications

The development of an all-in-focus algorithm for endoscopy

The development of an all-in-focus algorithm for endoscopy

Accurate and Rapid Auto-Focus Methods Based on Image Quality Assessment for Telescope Observation

Spectral characteristics of chromatic confocal imaging systems

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