Ahmed, "Visual enhancement of human observatory system using multi-scale retinex
," Informatics in Medicine Unlocked, Vol.
The white patch retinex
(WP) method  is similar to the Gray World  method, and it assumes that the area with the highest brightness in each channel of an image is the white area.
Sheng, "Extracting roads based on retinex
and improved canny operator with shape criteria in vague and unevenly illuminated aerial images," Journal of Applied Remote Sensing, vol.
Depending on the starting clarity of the photograph, either the Stretch Contrast plugin for GNU Image Manipulation Program (Quintero 1996) or Fred's ImageMagick Scripts retinex
enhancement algorithm (Weinhaus 2007) was applied.
Multi scale retinex
iUraiUka uPraUoma bendraja forma (5) (Leszczynski 2010; Petro et al.
 proposed the multiscale retinex
(MSR) method which estimated the reflectance component as the ratio of the image and its low-pass version that served as estimate for the illumination component.
The Multiscale Retinex
(MSR) algorithm in  processes each color channel individually and then removes the illumination component to keep reflection component.
The idea of Retinex
was introduced and pioneered by Land and McCann  to explain how a combination of processes occurs both in the "retina" and in the "cortex." Retinex
theory tells us that human visual system can ensure that the perceived colors of objects remain relatively constant under varying illumination conditions.
The referred CEs are, respectively, HE (histogram equalization) [12, 18], IN (intensity normalization) [13, 16], IHE (illumination estimation subtract and HE) , DHE (DoG filter and HE) , HF (homomorphic filter) , GC (gamma correction) , RASF (Retinex
and adaptive smoothing filter) , CLAHE (contrast limited adaptive histogram equalization) , related AHE (adaptive histogram equalization), CLHE (contrast limited histogram equalization), HHE (high frequency filtering and HE) , INE (image negative enhancement) , GLS (grey level slicing) , CS (contrast stretching) , LS (Laplacian sharpening) , UM (unsharp masking) , HBF (high-boost filtering) , and HEHBF (HE and HBF) .
theory was originally proposed by Land and is based on the human visual system .
Image enhancement operations such as Retinex
algorithm  and histogram equalization  is significant to provide better interpretability or perception of information in images for viewers, or to improve the input for other image processing techniques.