In digital color image capturing devices, or systems, such as, for example, digital cameras, digital endoscopes, and the like, a scene is typically captured by an image sensor, such as, for example, a Charge Coupled Device (CCD), a CMOS sensor, or the like. The scene captured by the image sensor is converted into image data by the image sensor. The image data is in the form of pixel values corresponding to the image. The image data is then processed through an imaging pipeline by making use of, for example, appropriate algorithms, or the like, so as to produce an output color image. A reason for processing the image data through the imaging pipeline is to produce an accurate color output image from the image capturing device, or system, at a specified output resolution.
Typically, the output color image has three primary color values per pixel. A typical color image is defined by three primary color planes of pixels, where each pixel is typically defined by a 3-tuple in a color space, such as, for example, the Red, Green and Blue (RGB) color space. Although RGB is one of the most common color spaces currently in use, there are many other color spaces. Some examples of such other color spaces include the CMY (Cyan, Magenta and Yellow), the YUV (where Y is the luminance and U and V represent chrominance), and the HSL (Hue, Saturation, and Lightness) color spaces.
Color accuracy, namely whether the color in the scene is accurately described by the output color image, is an important consideration in providing color image output quality. Color accuracy of an image capturing device, or system, may be influenced by, for example, the physical characteristics of the capturing device, the lighting condition in the scene during image capture, etc.
To produce an accurate color output image, it is important to compensate for distortion caused by the physical characteristics of the image capturing device. It is also important to compensate for distortion which can be caused when different lighting conditions, such as daylight, artificial lighting, are present in the scene. Such compensation may be provided by means of a color correction system of the image capturing device. For such a color correction system to perform properly, it is necessary to calibrate the color correction system. Calibration of the color correction system involves determining appropriate color compensation parameters. Once appropriate compensation parameters have been determined, the compensation parameters can be employed by the color compensation system to enable the image capturing device to produce relatively accurate color output images.
Appropriate compensation parameters can include gamma curves, color channel gains and offsets, color correction parameters, and the like.
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