Grayscale histogram generation

A computer program product, comprising:

• a non-transitory computer-readable storage device having computer-executable program instructions embodied thereon that when executed by a computer cause the computer to create grayscale histograms of input images:
• in a graphics processing unit (GPU):
• receive an input image comprising an array of pixels, each pixel having a grayscale value from a range of N grayscale values;
• for each particular input patch of pixels of a set of input patches partitioning the input image:
• in parallel for each particular grayscale value the range, count the number of pixels in the particular input patch having the particular grayscale value;
• and
• create an output image patch as an ordered sequence of N pixels, with the color value of the nth pixel in each corresponding output patch representing the count of pixels in the particular input patch having the nth grayscale value;
• format the color value of each pixel in the output image patch in RBGA unsigned integral format;
• and
• combine the output image patches into a single composite output image of N pixels, the pixel value of the nth pixel in the single composite output image corresponding to the count of pixels in the input image having the nth grayscale value;
• and
• generate an output image histogram comprising the composite output image.

A system to process a registration of a user in a mobile payment service being one of a plurality of services supported by a service provider, comprising:

• a storage device;
• and
• a processor communicatively coupled to the storage device, wherein the processor executes application code instructions that are stored in the storage device to cause the system to:
• in a graphics processing unit (GPU):
• receive an input image comprising an array of pixels, each pixel having a grayscale value from a range of N grayscale values;
• for each particular input patch of pixels of a set of input patches partitioning the input image:
• in parallel for each particular grayscale value the range, count the number of pixels in the particular input patch having the particular grayscale value;
• and
• create an output image patch as an ordered sequence of N pixels, with the color value of the nth pixel in each corresponding output patch representing the count of pixels in the particular input patch having the nth grayscale value;
• format the color value of each pixel in the output image patch in RBGA unsigned integral format;
• and
• combine the output image patches into a single composite output image of N pixels, the pixel value of the nth pixel in the single composite output image corresponding to the count of pixels in the input image having the nth grayscale value;
• and
• generate an output image histogram comprising the composite output image.