Mapping pulse propagation

An apparatus comprising:

• at least one processor;
• and
• at least one memory including computer program code,
• the at least one memory and the computer program code configured to, when executed by the at least one processor, cause the apparatus at least to:
• control capture of two images of an area, across which a pulse propagates, using different shutter scanning directions;
• obtain a color difference map identifying differences between the two images;
• convert the color difference map into a pulse-phase difference map;
• obtain a shutter-time difference map identifying differences between capture times of corresponding locations in the two images;
• and
• correct the pulse-phase difference map using the shutter-time difference map to obtain a map of pulse-phase changes which have occurred over a duration of a shutter scan.

A method comprising:

• controlling capture of two images of an area, across which a pulse propagates, using different shutter scanning directions;
• converting the images into pulse-phase maps of the area and obtaining a pulse-phase difference map identifying differences between the pulse-phase maps of the area;
• obtaining a shutter-time difference map identifying differences between capture times of corresponding locations in the two images;
• and
• correcting the pulse-phase difference map using the shutter-time difference map to obtain a map of pulse-phase changes which have occurred over a duration of a shutter scan.

A non-transitory computer readable medium comprising program instructions stored thereon for causing an apparatus to perform at least the following:

• controlling capture of two images of an area, across which a pulse propagates, using different shutter scanning directions;
• obtaining a color difference map identifying differences between the two images and converting the color difference map into a pulse-phase difference map;
• obtaining a shutter-time difference map identifying differences between capture times of corresponding locations in the two images;
• and
• correcting the pulse-phase difference map using the shutter-time difference map to obtain a map of pulse-phase changes which have occurred over a duration of a shutter scan.