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Shading correction for endoscopic images using principal color components

: Bergen, T.; Wittenberg, T.; Münzenmayer, C.


International journal of computer assisted radiology and surgery 11 (2016), No.3, pp.397-405
ISSN: 1861-6410
ISSN: 1861-6429
Journal Article
Fraunhofer IIS ()

Inhomogeneous illumination often causes significant shading and vignetting effects in images captured by an endoscope. Most of the established shading correction methods are designed for gray-level images. Only fewpapers have been published about howto compensate for shading in color images. For endoscopic images with a distinct red coloring, these methods tend to produce color artifacts.
A color shading correction algorithm for endoscopic images is proposed. Principal component analysis is used to calculate an appropriate estimate of the shading effect so that a one-channel shading correction can be applied without producing undesired artifacts.
The proposed method is compared to established YUV and HSV color-conversion-based approaches. It produces superior results both on simulated and on real endoscopic images. Example images of using the proposed shading correction for endoscopic image mosaicking are presented.
A new method for shading correction is presented which is tailored to images with distinct coloring. It is beneficial for the visual impression and further image analysis tasks.