Improving the quality of high dynamic range images

Abstract

High dynamic range (HDR) photography is a useful luminance measurement tool but relies on the camera and lens used and photometric calibration for its accuracy, yet these aspects lack technical guidance. This study used a Canon 350D camera fitted with a Sigma 10—20 mm lens to record the luminance data of 54 grey and 18 colour targets plus a light source in a windowless classroom lit by fluorescent lighting. Six apertures (f/4—f/22), three focal lengths (10, 14, 20 mm), two ambient light levels and four ranges of exposure values were used for generating 128 HDR images in Photosphere. After vignetting correction and physical calibration, these HDR images were compared with each other for the quality of luminance acquisition. This study could benefit future HDR imaging by ensuring higher image quality.

Camera preparation and performance for 3D luminance mapping of road environments

“…However, a large, ideally uniform luminance source is more a theoretical than a practical device. Therefore, it is more pragmatic to solve the vignetting for example by using a small diameter luminance source in a set of locations within the camera's field of view or a large diameter luminance source with its exit port covering the camera's full field of view (Inanici, 2006;Cai and Chung, 2011;Lu et al, 2016;Mead and Mosalam, 2017). Alternatively, vignetting information can be extracted from a set of images or a single image by applying an algorithmic method (Goldman and Chen, 2005;Zheng et al, 2008;Kim and Pollefeys, 2008;Zheng et al, 2009).…”

A Practical Device for Measuring the Luminance Distribution

“…These equations allowed to generate a nine-step exposure sequence to capture High Dynamic Range images. It has previously been shown that the quality of an HDR image does not significantly increase with a higher number of exposures [19]. Fig.…”

“…Standard 8-bit images only capture a dynamic range of 1.6 orders of magnitude [18]. The most common method to achieve a high dynamic range is the sequential exposure change technique [19]. With this technique, simple digital cameras are used to take Low Dynamic Range (LDR) photographs with sequential exposure settings to cover the desired dynamic range.…”

“…With this technique, simple digital cameras are used to take Low Dynamic Range (LDR) photographs with sequential exposure settings to cover the desired dynamic range. In order to keep the optical properties constant, it is recommended to only change the shutter speed [19].…”

Application of High-Dynamic Range Imaging Techniques in Architecture: A Step toward High-Quality Daylit Interiors?

“…It also makes possible statistical analyses of luminances of specific surfaces/areas of interest. The accuracy of luminance measurement with HDR photography is widely influenced by the care taken during acquisition and treatment [5][6][7]. A measurement error of less than 10% can be expected [6].…”