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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), Nr.3, S.397-405
ISSN: 1861-6410
ISSN: 1861-6429
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.