Methods and apparatus for reducing spatial flicker artifacts

A method for reducing spatial artifacts in multi-exposure images comprising:

• generating, with an image sensor comprising an array of color pixels arranged in rows and columns, first image pixel data corresponding to pixels having a first exposure time, and second image pixel data corresponding to pixels having a second exposure time, wherein the first exposure time is greater than the second exposure time;
• wherein the pixels used to generate the first and second image pixel data have the same spatial locations within the array;
• wherein the first and second image pixel data comprise a value representing light intensity;
• identifying whether the value is one of a valid or an invalid image pixel data;
• generating a ratio utilizing the valid image pixel data;
• wherein:
• the ratio comprises a first individual pixel value divided by a second individual pixel value;
• the first individual pixel value corresponds to a first color;
• the second individual pixel value corresponds to a second color that is different from the first color;
• and
• the first and second individual pixel values have a same exposure time;
• normalizing the computed ratio utilizing an ideal ratio, wherein the ideal ratio is the first exposure time divided by the second exposure time, and
• modifying the second image pixel data using the normalized ratio.

A system for producing flicker-free images of a scene illuminated by a light using an alternating current source, comprising:

• an image sensor, comprising:
• a color filter array comprising a plurality of color filters situated on an array of pixels arranged in rows and columns, wherein the image sensor obtains:
• first image pixel data corresponding to pixels having a first exposure time, and
• second image pixel data corresponding to pixels having a second exposure time;
• wherein the first exposure time is greater than the second exposure time;
• wherein the pixels used to generate the first and second image pixel data have the same spatial locations within the array;
• a storage unit coupled to the image sensor, wherein the storage unit stores the first and second image pixel data;
• an image signal processor coupled to the storage unit, wherein the image signal processor:
• identifies valid and invalid image pixel data based on a pixel data value;
• generates a color ratio utilizing the valid image pixel data;
• wherein:
• the ratio comprises a first individual pixel value divided by a second individual pixel value;
• the first individual pixel value corresponds to a first color from the plurality of color filters;
• the second individual pixel value corresponds to a second color from the plurality of color filters that is different from the first color;
• and
• the first and second individual pixel values have a same exposure time;
• normalizes the color ratio utilizing an ideal ratio, wherein the ideal ratio is the first exposure time divided by the second exposure time;
• modifies the second image pixel data using the normalized color ratio to form corrected image pixel data;
• and
• combines the corrected image pixel data with the first image pixel data to form a multi-pixel data image;
• and
• an I/O device for displaying the multi-pixel data image.