Apple Inc.
PER-PIXEL PHOTOMETRIC CONTRAST ENHANCEMENT WITH NOISE CONTROL

Abstract:

Embodiments relate to enhancing local contrast in an image. A bilateral high pass filter generates a high frequency value for each pixel of an input image, based on a convolution using photometric kernel coefficients associated with other pixels around the pixel. A noise control circuit generates a modulated high frequency value for the pixel based on a noise model for the image defining a noise threshold value for modifying the high frequency value. The modulated high frequency value for the pixel is then combined with a pixel value of the pixel to generate an enhanced value for the pixel. Enhanced values for pixels of the image may be generated to provide the local contrast enhancement for the input image.