The Camera Pipeline

UPF's recent paper on the common assumption about the camera pipeline, and the impact this has on HDRI imaging was reported in SciTechDaily under the heading Conventional Methods for Obtaining HDR Images Are Wrong. The paper explains that "HDR image generation is based on a couple of wrong assumptions. First, that color channels are independent and, secondly, that camera response function (CRF) remains constant while changing the exposure". They found that whilst these assumptions held true for film photography, they do not hold for digital cameras, causing problems such as hue shifts and colour artefacts.

R. Gil Rodríguez , J. Vazquez-Corral, and M. Bertalmío

Multiple-exposure approaches for high dynamic range (HDR) image generation share a set of building assumptions: that color channels are independent and that the camera response function (CRF) remains constant while changing the exposure. The first contribution of this paper is to highlight how these assumptions, which were correct for film photography, do not hold in general for digital cameras. As a consequence, results of multiexposure HDR methods are less accurate, and when tone-mapped they often present problems like hue shifts and color artifacts. The second contribution is to propose a method to stabilize the CRF while coupling all color channels, which can be applied to both static and dynamic scenes, and yield artifact-free results that are more accurate than those obtained with state-of-the-art methods according to several image metrics.

Find out more about our work on the Asset Pipeline Here