High‐precision refocusing method with one interpolation for camera array images

Abstract

Camera array image refocusing can change the in-focus region so that objects lying on a specified plane are in focus, whereas objects lying off this plane are blurred. Existing refocusing methods for camera array or light field images usually contain two interpolations. Since interpolation brings distortion, especially on the sharp edge in the images, existing methods are not sufficiently precise. In order to improve the quality of the refocusing result, the authors propose a high-precision method to refocus camera array images. They first back-project the pixel coordinates to a corresponding location on the focal plane in the world coordinate. Then they reproject the world coordinates to the pixel coordinates by using the parameters of each camera in the array. After that, they align the images with the focal plane by employing interpolation according to the acquired pixel coordinates. Finally, they get the synthetic image refocused on the focal plane by averaging the resulted images. In the proposed method, only one interpolation is used. So that it alleviates the quality degradation of the refocused image compared to the existing methods. Experiments on real-world scenes (captured by their self-developed light field devices) demonstrate that their method can yield better results than the existing methods.

Calibration and Target Signal-to-Noise Ratio Enhancement Method of Infrared Camera Array Based on Refocus

“…To eliminate the influence of camera distortion, Zhang's calibration method calculates the intrinsic matrices and reprojection errors. The intrinsic matrix is given as equation (1).…”

“…The camera array uses multiple cameras at different spatial locations to collect photos with different perspectives. The supplementary information provides the possibility of many applications such as post-capture refocusing [1] [2], super-resolution [3], view synthesis [4] and de-occlusion [5]. Wilburn et al [6] used cheap cameras to build a high-performance camera array, which is utilized for high-resolution and high-dynamic-range video capture, spatiotemporal view interpolation, non-linear synthetic aperture photography etc.. Vaish et al [7] also had relative work with the support of camera array.…”

Review of light field technologies

“…The rendered bokeh image was then used as a regularization term to generate refocused images. Moreover, Yang et al [ 63 ] proposed a refocusing framework that produced coordinates for interpolation, and they aligned the images onto the focal plane.…”

An Infrared Camera Array Calibration Method using Constant Temperature Heating Checkboard

“…Introduction: Traditional camera calibration method usually considers a single camera or dual cameras. As the growing development of imaging technology, multi camera and camera array are used in more and more application [1][2][3][4][5]. Camera calibration plays an important role in the application of infrared camera array [6].…”

“…{𝐾 } = {𝐾 (1) , 𝐾 (2) , 𝐾 (3) , 𝐾 (4) } {𝑘} = { 𝑘 (1) 1 ,𝑘 (1) 2 ,𝑘 (1) 3 ,𝑘 (2) 1 ,𝑘 (2) 2 ,𝑘 (2) 3 ,𝑘 (3) 1 ,𝑘 (3) 2 ,𝑘 (3) 3 ,𝑘 (4) 1 ,𝑘 (4) 2 ,𝑘 (4) 3 } { 𝑝} = { 𝑝 (1) 1 , 𝑝 (1) 2 , 𝑝 (2) 1 , 𝑝 (2) 2 , 𝑝 (3) 1 , 𝑝 (3) 2 , 𝑝 (4) 1 , 𝑝 (4) 2 } {[𝑅 𝑗 𝑇 𝑗 ]} = {[𝑅 (1) 𝑗 𝑇 (1) 𝑗 ],[𝑅 (2) 𝑗 𝑇 (2) 𝑗 ],[𝑅 (3) 𝑗 𝑇 (3) 𝑗 ], [𝑅 (4) 𝑗 𝑇 (4) 𝑗 ]} 𝑚 𝑗 𝑘 = [𝑢 (1) 𝑗 𝑘 , 𝑣 (1) 𝑗 𝑘 , 1, 𝑢 (2) 𝑗 𝑘 , 𝑣 (2) 𝑗 𝑘 , 1, 𝑢 (3) 𝑗 𝑘 , 𝑣 (3) 𝑗 𝑘 , 1, 𝑢 (4) 𝑗 𝑘 , 𝑣 (4) 𝑗 𝑘 , 1] 𝑇 𝑀 𝑘 = [𝑥 (𝑤) 𝑘 ,𝑦 (𝑤) 𝑘 ,1,𝑥 (𝑤) 𝑘 ,𝑦 (𝑤) 𝑘 ,1,𝑥 (𝑤) 𝑘 ,𝑦 (𝑤) 𝑘 ,1,𝑥 (𝑤) 𝑘 ,𝑦 (𝑤) Experimental results: We used our 2 × 2 infrared camera array and constant temperature heating checkboard for calibration experiments. We rotate and translate the checkboard to obtain 15 different poses.…”