No-Reference Spatial Aliasing Measure for Digital Image Resizing

A device comprising:

• a directional image module to identify patches in an image that contain strong directional energy and to estimate a quantized direction for each patch;
• a partitioning module that, for each patch, partitions a total energy into estimated signal energy and estimated aliasing energy based on aliasing locations predicted by the estimated quantized direction;
• and
• an estimate module to combine the estimated signal energy and the estimated aliasing energy of each patch to obtain an estimate of the severity of an aliasing error in the image.

A device comprising:

• a processor;
• and
• a computer-readable storage medium comprising operational instructions that, when executed by the processor, cause the processor to:
• measure jagginess in an image caused by aliasing by looking for image regions with strong directional energy;
• obtain a direction of the strong directional energy to determine the frequency location of any potential aliasing;
• estimate an aliasing at the frequency location of any potential aliasing and form an estimate of the signal without aliasing;
• and
• form a signal-to-aliasing ratio over all processed patches to obtain an overall image measure of the impact of aliasing on the image.