We present an effective method for defocus map estimation from a single natural image. It is inspired by the observation that defocusing can significantly affect the spectrum amplitude at the object edge locations in an image. By establishing the relationship between the amount of spatially varying defocus blur and spectrum contrast at edge locations, we first estimate the blur amount at these edge locations, then a full defocus map can be obtained by propagating the blur amount at edge locations over the entire image with a nonhomogeneous optimization procedure. The proposed method takes into consideration not only the affect of light refraction but also the blur texture of an image. Experimental results demonstrate that our proposed method is more reliable in defocus map estimation compared to various state-of-the-art methods.
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http://dx.doi.org/10.1364/OL.38.001706 | DOI Listing |
JMIR Dermatol
December 2024
K.E.M. Hospital, Mumbai, India.
Background: Thus far, considerable research has been focused on classifying a lesion as benign or malignant. However, there is a requirement for quick depth estimation of a lesion for the accurate clinical staging of the lesion. The lesion could be malignant and quickly grow beneath the skin.
View Article and Find Full Text PDFThe separability of patterns in a light-intersected area is the fundamental property of multi-view fringe projection profilometry (FPP). The traditional method based on temporal discrete Fourier transform separation and periodic wrapped phase requires dozens of patterns for each reconstruction. To enhance projection efficiency in multi-view FPP, a phase texture technique is proposed to reduce the pattern number by encoding the wrapped phase as an aperiodic texture.
View Article and Find Full Text PDFIEEE Trans Pattern Anal Mach Intell
December 2024
Sensors (Basel)
March 2024
College of Intelligent Equipment, Shandong University of Science and Technology, Tai'an 271019, China.
Fringe projection profilometry (FPP), with benefits such as high precision and a large depth of field, is a popular 3D optical measurement method widely used in precision reconstruction scenarios. However, the pixel brightness at reflective edges does not satisfy the conditions of the ideal pixel-wise phase-shifting model due to the influence of scene texture and system defocus, resulting in severe phase errors. To address this problem, we theoretically analyze the non-pixel-wise phase propagation model for texture edges and propose a reprojection strategy based on scene texture modulation.
View Article and Find Full Text PDFIn current optical systems, defocus blur is inevitable due to the constrained depth of field. However, it is difficult to accurately identify the defocus amount at each pixel position as the point spread function changes spatially. In this paper, we introduce a histogram-invariant spatial aliasing sampling method for reconstructing all-in-focus images, which addresses the challenge of insufficient pixel-level annotated samples, and subsequently introduces a high-resolution network for estimating spatially varying defocus maps from a single image.
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