Features generation and spotting methods and systems using same

An image analyzer comprising:

• an image partitioner configured to find a partition point that divides a received image into four sub-images each having a pre-selected activated pixel count, wherein the image partitioner includes:
• an integrator configured to compute a two-dimensional integral image from the received image, and
• a partition point optimizer configured to iteratively improve an initial partition point to find the partition point that divides the received image into four sub-images each having a pre-selected activated pixel count, the partition point optimizer using pixel values of the two-dimensional integral image to compute a partition point figure-of-merit for each iterative improvement;
• a recursion processor configured to (i) apply the image partitioner to an input image to generate a first partition point and four sub-images and to (ii) recursively apply the image partitioner to at least one of the four sub-images for at least one recursion iteration to generate at least one additional partition point and additional sub-images;
• and
• a formatter configured to generate a features representation of the input image in a selected format, the features representation being based at least in part on the partition points;
• wherein the image analyzer comprises a digital device with at least one processor programmed to implement at least the image partitioner and recursion processor.