Quadrants dynamic histogram equalization for contrast enhancement

• Published in: IEEE transactions on consumer electronics Vol. 56; no. 4; pp. 2552 - 2559
• Main Authors: Chen Hee Ooi, Isa, Nor Ashidi Mat
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.11.2010; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Brightness; Devices; Dynamic range; Dynamics; Electronics; Equalization; Heuristic algorithms; Histograms; Marine animals; Pixel; Quadrants; dynamic histogram equalization; contrast enhancement; partitioned histogram; Histogram equalization
• ISSN: 0098-3063; 1558-4127
• DOI: 10.1109/TCE.2010.5681140

In this paper, we introduce a histogram equalization (HE)-based technique, called quadrant dynamic histogram equalization (QDHE), for digital images captured from consumer electronic devices. Initially, the proposed QDHE algorithm separates the histogram into four (quadrant) sub-histograms based on the median of the input image. Then, the resultant sub-histograms are clipped according to the mean of intensity occurrence of input image before new dynamic range is assigned to each sub-histogram. Finally, each sub-histogram is equalized. Based on extensive simulation results, the QDHE method outperforms some methods existing in literature, which can be considered as state-of-the-arts, by producing clearer enhanced images without any intensity saturation, noise amplification, and over-enhancement. Furthermore, image details of the processed image are well preserved and highlighted. For this reason, the proposed QDHE algorithm is suitable for images captured in low-light environments - an unavoidable situation by many consumer electronics products such as camera devices in cell phone.