pfftcorrelation

Synopsis

Description

pfftcorrelation performs a correlation between the two input images im_in1 and im_in2. The correlation determines the degree of likeness between the two images. The first input images im_in1 size must be greater or equal than the second input image im_in2 size.

The correlation uses the frequency domain. It consists of a complex multiplication of the Fourier transform of the first input images and the complex conjugate of the second input image im_in2:

• imi=fft(im_in) * conj(fft(im_in2))
• im_out=iift(imi);

where * is the complex multiplication and conj(im) is the complex conjugate of im.

Inputs

• im_in1: a 2D image.
• im_in2: a 2D image (same type and size as im_in1).

Outputs

• im_out: a float image.

Result

Returns SUCCESS or FAILURE.

Examples

Detects presence of tangram pieces in the tangram.pan image:

   pextractsubimage 111 6 0 35 32 0 tangram.pan a.pan  
   pfftcorrelation tangram.pan a.pan b.pan
   plocalmaxima 8 b.pan out.pan

See also

Prototype C++