Chroma noise reduction for cameras

A method of reducing noise in an image comprising:

• receiving a first digital image representative of a physical scene and comprising a plurality of pixels, wherein each pixel has a color value;
• blurring at least a first portion of the plurality of pixels, wherein the at least first portion of the plurality of pixels comprises:
• a first center pixel;
• N1 pixels in a first direction of the first center pixel;
• and
• N2 pixels in a second direction of the first center pixel,
• and wherein the blurring of the at least first portion of the plurality of pixels comprises:
• using a computer processor to compute a first value for the first center pixel,
• wherein the first value is calculated using the formula:
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• wherein Cn is a color value associated with a pixel, C0 is a color value associated with a center pixel, and Tn is determined at least in part by a color distance measurement between Cn and C0;
• transforming the color value of the first center pixel to be equal to the computed first value;
• and
• storing the transformed color value of the first center pixel in a memory.

An apparatus, comprising:

• a camera sensor unit;
• memory operatively coupled to the camera sensor unit for receiving image data representative of an image of a physical scene and comprising a plurality of pixels;
• and
• a processor unit operatively coupled to the memory, the memory comprising instructions for causing the processor unit to:
• read a first portion of the image data corresponding to a first plurality of pixels, wherein each pixel in the first plurality of pixels has a color value, and wherein one pixel within the first plurality of pixels is a first center pixel;
• compute a first value for the first center pixel, wherein the first value is based at least in part on the color value of each pixel in the first plurality of pixels having a color value that differs from the color value of the first center pixel by less than a specified threshold, wherein the specified threshold is determined dynamically for the image based at least in part on metadata of the image, and wherein the metadata comprises gain;
• transform the color value of the first center pixel to be equal to the computed first value;
• and
• store the transformed color value of the first center pixel in the memory.