Sensor data processing

Apparatus for processing sensor data, the apparatus comprising:

• a sensor for measuring values of a parameter over a region of interest to produce an image of the region of interest, the image having a plurality of pixels;
• and
• one or more processors arranged to:
• for each pixel, determine an orientation of a gradient of the parameter, at that pixel, using the measured parameter values;
• for each of a plurality of predetermined ranges of gradient orientation values, determine a number of said pixels that have a gradient orientation value within that range;
• determine a number of groups of predetermined ranges, wherein each group of predetermined ranges is to satisfy a criteria that:
• for each predetermined range in that group, the number of said pixels that have a gradient orientation value within that range is above a threshold value;
• and
• if that group comprises more than one predetermined range, each predetermined range in that group is contiguous with at least one other predetermined range in that group;
• and
• using the determined the number of groups, discriminate between presence of a man-made object and clutter in the image.

A machine readable storage medium storing in a non-transitory medium a program or a plurality of programs for causing a computer to execute a method which comprises:

• (i) using a sensor, measuring parameter values of a parameter over a region of interest to produce an image of the region of interest, the image having a plurality of pixels;
• (ii) for each pixel, determining an orientation of a gradient of the parameter, at that pixel, using the measured parameter values;
• (iii) for each of a plurality of predetermined ranges of gradient orientation values, determining a number of said pixels that have a gradient orientation value within that range;
• (iv) determining a number of groups of predetermined ranges, wherein each group of predetermined ranges satisfies a criteria that:
• for each predetermined range in that group, a number of said pixels that have a gradient orientation value within that range is above a threshold value;
• and
• if that group contains more than one predetermined range, each predetermined range in that group is contiguous with at least one other predetermined range in that group;
• and
• (v) using the determined the number of groups, discriminating between the presence of a man-made object and clutter in the image.