F2QCorrelation


Author V. C. Mohan
11 May 2021

This function operates in frequency domain and requires for 32 bit avisynth+ FFTw3 32 bit dll or for 64 bit avisynth+ FFTw3 64 bit dll. As these dll s are not thread safe this function operates in MT_SERIALIZED state.

F2QCorrelation function has 2 input clips and dsplays centered correlation in image domain. Gamma enables display in proper amplitude. The correlation maximum point coordinates frame wise can be output in a txt file. This works only if txt is set true and a valid output file name with complete path is specified. Note the video file need to be closed to get the full file output.

Only Green color of RGB formats is used, in case of other formats Y plane is used for correlation.

It may be noted internally the frame size may be increased for optimization of fft and this optimized size frame is output.



Details of parameters
Description Name Type Limits Default
Input referance A clip clip must have the fields separated none
Input B clip clip must have identical format and dimensions of A clip none
gamma scaling for viewing convenience gamma float 4.0
Whether correlation text file to be generated. txt boolean true false. false
Full path and name of text file to be generated. file string a valid file name must be specified if txt is set true none
frame number from which text file to be output. sf int within video 0
frame number up to which text file to be output. ef int within video and not less than sf end frame of video
intervals of frames for text output. every int ensure not more than 1000 records are output (ef - sf) / 1000 + 1

#Usage examples:-
# for text file output
F2QCorrelation(b,a, 4.0, true, txt = true, file = "C:\Documents\corr.txt")
#for visual output only
F2QCorrelation(b,a, 1.6, true)


below is an illustration of output using the script .
loadplugin("......./F2QPlus.dll")
loadplugin("......../Grid.dll")
a = addborders(last,0,0,160,148)
b = addborders(last,160,148,0,0)#.invert()
F2QCorrelation(b,a, 4.0, true)
# grid axis display to aid visual estimate
grid(grid = false,axis = true,color = $ff, bcolor = $ffff, vbcolor = $ffffff) 

To my index page down load plugin To Avisynth