Digital color image pre-processing
View Patent ↗In one embodiment, the invention involves a method for processing an image. A sensor output is provided. An automatic gain control of the sensor output is performed to generate a first output. An automatic white balance correction to the first output is performed to generate a second output. A gamma correction of the second output is performed to generate a third output. A color interpolation is performed to the third output to generate a fourth output. A low-pass spatial filtration of the fourth output is performed to generate a fifth output. A color saturation and correction of the fifth output is performed to generate a sixth output, and a high-pass spatial filtration of the sixth output is performed to generate an image output.
1. A method for processing an image, comprising:
providing a sensor output;
performing an automatic gain control of the sensor output to generate a first output,
wherein the automatic gain control is applied in a digital domain, including
performing an expansion of a histogram to fill a dynamic range;
performing an automatic white balance correction to the first output to generate a second output;
performing a gamma correction of the second output to generate a third output, wherein
the gamma correction performs a variable gamma correction to increase a
dynamic range of an image included in the second output;
performing a color interpolation to the third output to generate a fourth output;
performing a low-pass spatial filtration of the fourth output to generate a fifth output,
wherein the low-pass spatial filtration is for eliminating a fixed pattern noise in a flat field;
performing a color saturation and correction of the fifth output to generate a sixth output; and
performing a high-pass spatial filtration of the sixth output to generate an image output.
2. The method of claim 1 , wherein the automatic white balance correction comprises calculating a gray world model ratio of a set of colors in a pattern and applying a multiplier to each color.
3. The method of claim 1 , wherein the gamma correction is performed in gray space.
4. The method of claim 1 , wherein the color interpolation comprises performing a three-by-three edge enhanced demosaic of a raw Bayer signal to an RGB signal.
5. The method of claim 1 , wherein the low-pass spatial filtration comprises performing a low-pass spatial filter on each of a plurality of color planes.
6. The method of claim 1 , wherein the color saturation and correction comprises manipulating color ratios of a plurality of color planes within each of a plurality of pixels.
7. The method of claim 1 , wherein the high-pass spatial filtration comprises enhancing a spatial edge.
8. An imaging device configured to implement the method of claim 1 .
9. An application specific integrated circuit configured to implement the method of claim 1 .