Image artifacts in hybrid imaging systems with a cubic phase mask

Demenikov, Mads; Harvey, Andrew R.

doi:10.1364/oe.18.008207

Cited by 64 publications

(32 citation statements)

References 13 publications

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“…Translation, ρ, is parallel to the ξ η direction in the image plane and is proportional to W [2,7,9,23]. The value of optical defocus, W 20 , used to record an image can thus be determined by identifying the matchingW 20 that produces no displacement between the recovered images corresponding to ψ and ψ .…”

Section: Theory and Simulationmentioning

confidence: 99%

“…Image recovery with a single kernel therefore introduces phase mismatches between the coding optical phasetransfer function (PTF) and the PTF of the digital filter used for image recovery, leading to range-dependent translation and image-replication artifacts [9]. It is perhaps for these reasons that practical exploitation of this so-called wavefront coding (WC) technique appears to have slowed in recent years.…”

Section: Introductionmentioning

confidence: 99%

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Extended depth-of-field imaging and ranging in a snapshot

Zammit¹,

Harvey²,

Carles³

2014

Optica

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Traditional approaches to imaging require that an increase in depth of field is associated with a reduction in numerical aperture, and hence with a reduction in resolution and optical throughput. In their seminal work, Dowski and Cathey reported how the asymmetric point-spread function generated by a cubic-phase aberration encodes the detected image such that digital recovery can yield images with an extended depth of field without sacrificing resolution [Appl. Opt. 34, 1859(1995]. Unfortunately recovered images are generally visibly degraded by artifacts arising from subtle variations in point-spread functions with defocus. We report a technique that involves determination of the spatially variant translation of image components that accompanies defocus to enable determination of spatially variant defocus. This in turn enables recovery of artifact-free, extended depth-of-field images together with a two-dimensional defocus and range map of the imaged scene. We demonstrate the technique for high-quality macroscopic and microscopic imaging of scenes presenting an extended defocus of up to two waves, and for generation of defocus maps with an uncertainty of 0.036 waves.

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Section: Theory and Simulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Extended depth-of-field imaging and ranging in a snapshot

Zammit¹,

Harvey²,

Carles³

2014

Optica

Self Cite

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“…Though different inverse filtering strategies can be used to reduce this effect, the restoration process that reconstructs the MTF (recovering the diffraction limited properties of the system) includes noise amplification in the final images [6,7]. On the other hand, image quality is also reduced by the appearance of image restoration artefacts due to the mismatch between the actual wavefront that forms the image and the opticaltransfer-function (OTF) used in the digital processing stage to restore it [8]. Although the invariance provided by the PM makes this difference small, when applied to scenes with extension, artifacts will appear.…”

Section: Wavefront Coding Frameworkmentioning

confidence: 99%

“…On the other side, it has been shown how the defocus may also be estimated from the strength of the restoration artefacts within the wavefront coding strength [8]. However, again, this approach is proposed to deal with images affected by uniform defocus, and its reliability will be reduced as the ROI becomes smaller.…”

Section: Defocus Estimationmentioning

confidence: 99%

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Design and implementation of a scene-dependent dynamically selfadaptable wavefront coding imaging system

Carles

Ferran

Carnicer

et al. 2012

Computer Physics Communications

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A computational imaging system based on wavefront coding is presented. Wavefront coding provides an extension of the depth-of-field at the expense of a slight reduction of image quality. This trade-off results from the amount of coding used. By using spatial light modulators, a flexible coding is achieved which permits it to be increased or decreased as needed. In this paper a computational method is proposed for evaluating the output of a wavefront coding imaging system equipped with a spatial light modulator, with the aim of thus making it possible to implement the most suitable coding strength for a given scene. This is achieved in an unsupervised manner, thus the whole system acts as a dynamically selfadaptable imaging system. The program presented here controls the spatial light modulator and the camera, and also processes the images in a synchronised way in order to implement the dynamic system in real time. A prototype of the system was implemented in the laboratory and illustrative examples of the performance are reported in this paper. The program implements an enhanced wavefront coding imaging system able to adapt the degree of coding to the requirements of a specific scene. The program controls the acquisition by a camera, the display of a spatial light modulator and the image processing operations synchronously. The spatial light modulator is used to implement the phase mask with flexibility given the trade-off between depth-of-field extension and image quality achieved. The action of the program is to evaluate the depth-of-field requirements of the specific scene and subsequently control the codifing established by the spatial light modulator, in real time.

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