Identifying contiguous regions of constant pixel intensity in images

A computing system, comprising:

• a processing system including a processor;
• and
• a storage device for storing machine-readable instructions,
• the processing system executing the machine-readable instructions in the storage device to perform operations comprising:
• obtaining a candidate image;
• determining whether the candidate image contains a contiguous region of pixel intensity values within a specified range of intensity values,
• the determining involving determining a distribution of pixel intensity values within the candidate image, and, guided by the distribution of pixel intensity values, searching the candidate image for neighboring pixels having pixel intensity values within the specified range of pixel intensity values;
• upon determining that the candidate image contains the contiguous region, assessing whether the contiguous region satisfies a prescribed test, wherein the test also involves determining whether the contiguous region intersects with at least one edge of the candidate image by a prescribed amount;
• and
• selecting or excluding the candidate image for further processing based on a result of the assessing.

A computer-readable storage medium for storing computer-readable instructions, wherein a processing system executes the computer-readable instructions to perform operations comprising:

• obtaining a candidate image;
• generating a distribution of pixel intensity values in the candidate image, each of the pixel intensity values expressing a pixel intensity of a corresponding pixel in the candidate image;
• determining a quantity of pixels in an identified portion of the distribution, the identified portion demarcating a range of pixel intensity values in the distribution;
• sorting pixels in the identified portion with respect to location of the pixels in the identified portion across the candidate image, with respect to at least one axis of the candidate image, to produce a sorted set of pixels;
• determining whether the candidate image contains a contiguous region of pixel intensity values having intensity values within the range of intensity values, wherein the determining whether the candidate image contains a contiguous region of pixel intensity values is performed for a specified subset of pixels in the sorted set of pixels, and wherein a search for pixels having pixel intensity values within the range of pixel intensity values is commenced from a starting pixel in the subset of pixels upon determining that the pixels in the subset of pixels are spatially-connected pixels and share a same position on one axis of the candidate image;
• and
• upon determining that the candidate image contains the contiguous region, assessing whether the contiguous region satisfies a prescribed test.