A good brightness preserving contrast enhancement method has several applications especially in consumer electronics. A novel contrast enhancement method based on histogram equalization has been proposed in this paper. The method divides the histogram of an image into four sub histograms. Then, clipping is applied on each sub histogram. The clipping threshold of each sub histogram is taken as the difference between the median and standard deviation of the occupied intensities which gives a smoother cumulative distribution function and leads to better equalization of the sub histograms resulting in a good enhancement. Each sub histogram is assigned a new range and histogram equalization is done independently.
Contrast enhancement Brightness preserving Histogram equalization Standard deviation
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Gonzalez RC, Woods RE (2008) Digital image processing, 3rd edn. Prentice Hall, Upper Saddle RiverGoogle Scholar
Yun SH, Kim JH, Kim S (2010) Image enhancement using a fusion framework of histogram equalization and Laplacian pyramid. IEEE Trans Consum Electron 56(4):2763–2771CrossRefGoogle Scholar
Kim YT (1997) Contrast enhancement using brightness preserving bi histogram equalization. IEEE Trans Consum Electron 43(1):1–8CrossRefGoogle Scholar
Wan Y, Chen Q, Zhang BM (1999) Image enhancement based on equal area dualistic sub-image histogram equalization method. IEEE Trans Consum Electron 45(1):68–75CrossRefGoogle Scholar
Chen SD, Ramli AR (2003) Minimum mean brightness error bi histogram equalization in contrast enhancement. IEEE Trans Consum Electron 49(4):1310–1319CrossRefGoogle Scholar
Chen SD, Ramli AR (2003) Contrast enhancement using recursive mean-separate histogram equalization for scalable brightness preservation. IEEE Trans Consum Electron 49(4):1301–1309CrossRefGoogle Scholar
Sim KS, Tso CP, Tan YY (2007) Recursive sub-image histogram equalization applied to gray-scale images. Pattern Recognit Lett 28:1209–1221CrossRefGoogle Scholar
Kim M, Chung MG (2008) Recursively separated and weighted histogram equalization for brightness preservation and contrast enhancement. IEEE Trans Consum Electron 54(3):1389–1397CrossRefGoogle Scholar
Ooi CH, Kong NSP, Ibrahim H (2009) Bi-histogram equalization with a plateau limit for digital image enhancement. IEEE Trans Consum Electron 55(4):2072–2080CrossRefGoogle Scholar
Kim T, Paik J (2008) Adaptive contrast enhancement using gain controllable clipped histogram equalization. IEEE Trans Consum Electron 54(4):1803–1810CrossRefGoogle Scholar
Ooi CH, Isa NAM (2010) Adaptive contrast enhancement methods with brightness preserving. IEEE Trans Consum Electron 56(4):2543–2551CrossRefGoogle Scholar