Color image processing for digital cameras

Organic Photodiodes: The Future of Full Color Detection and Image Sensing

“…Although considered the best in image quality and resolution, 3-CCD cameras are generally more expensive than single-sensors and the potential for miniaturization is somewhat limited. [ 35,52 ] The fourth approach is an emerging technology -the integrated color pixel (ICP), which involves replacement of the CFA with an array of metal strips in a specifi c pattern, enabling color separation during image capture (Figure 2 d). The patterned metal layers (which may be 1D or 2D) are placed above each photodetector and control the transmission of light to the photodetector within the pixel.…”

“…This method is mainly used for professional studio cameras (still-life), as subject motion causes distorted color images. [ 35 ] The third approach (Figure 2 c) mainly applies to video imaging systems and involves the use of a beam-splitter that is able to separate the light into its red, green and blue components, which are then focused onto three discrete image sensors (a three-chip system). This system is commonly referred to as 3-CCD or 3-CMOS.…”

“…Although there are several arrangements of fi lters, a common system employs the Bayer fi lter, [ 40 ] which consists of a mosaic of red (R), green (G) and blue (B) fi lters such that there are twice as many Gs as there are R and B, thereby representing the human visual system (HVS). [ 35,46 ] Once the image has been captured, there follows a complex "demosaicing" process, which relies on the use of algorithms to extrapolate a set of complete red, green, and blue values for each point of the Bayer pattern image, ultimately resulting in the formation of a [ 8 ] Copyright 2014, IC Insights.…”

“…[ 34 ] Importantly, the type of photodetector material and color separation system associated with the image sensor play a dominant role in defi ning the quality of the fi nal image since they determine the spectral sensitivity, linear dynamic range, color accuracy and resolution. [ 35 ] In addition, the photodetector material plays a large part in determining the physical properties of the image sensor (fl exibility, size, and weight), which then determines the properties and applications of the sensing device. [ 36 ] Photodiodes (PDs) offer a simple device structure [ 37 ] and can essentially be grouped into those photodetectors that absorb across a broad wavelength range (broadband or panchromatic) and those specifi cally designed for color imaging in which a narrow wavelength band is targeted (narrowband or monochromatic).…”