MatLab function: sfrmat3 Slanted-edge Analysis for digital camera and scanner
evaluation. Updated version of sfrmat2.
[status, dat, fitme, esf, nbin, del2] = sfrmat3(io, del, weight, a, oecfname);
From a selected edge area of an image, the program computes
the ISO slanted edge SFR. Input file can be single or
three-record file. Many image formats are supported. The image
is displayed and a region of interest (ROI) can be chosen, or
the entire field will be selected by not moving the mouse
when defining an ROI (simple click). Either a vertical or horizontal
edge features can be analized.
Input arguments:
io (optional)
0 = (default) R,G,B,Lum SFRs + edge location(s)
= 'sfrmat2' R,G,B,Lum SFRs + edge location(s)but
with the same calculations as the previous version, sfrmat2
1 = Non GUI usage with supplied data array
del (optional) sampling interval in mm or pixels/inch
If dx < 1 it is assumed to be sampling pitch in mm
If io = 1 (see below, no GUI) and del is not specified,
it is set equal to 1, so frequency is given in cy/pixel.
weight (optiona) default 1 x 3 r,g,b weighs for luminance weighting
a (required if io =1) an nxm or nxmx3 array of data
oename optional name of oecf LUT file containing 3xn or 1xn array
Returns:
status = 0 if normal execution
dat = computed sfr data
fitme = coefficients for the linear equations for the fit to
edge locations for each color-record. For a 3-record
data file, fitme is a (4 x 3) array, with the last column
being the color misregistration value (with green as
reference).
esf = supersampled edge-spread functin array
nbin = binning factor used
del2 = sampling interval for esf, from which the SFR spatial
frequency sampling is was computed. This will be
approximately 4 times the original image sampling.
EXAMPLE USAGE:
sfrmat3 file and ROI selection and
sfrmat3(1) = GUI usage
sfrmat3(0, del) = GUI usage with del as default sampling in mm
or dpi
sfrmat3(2, del, weight) = GUI usage with del as default sampling
in mm or dpi and weight as default luminance
weights
sfrmat3(4, dat) = non-GUI usage for data array, dat, with default
sampling and weights aplied (del =1,
weights = [.3 .6 .1])
[status, dat, fitme] = sfrmat3(4, del, weight, a, oecfdat);
sfr and edge locations, are returned for data
array dat using oecf array, oecfdat, with
specified sampling interval and luminance weights
Provided in support of digital imaging performance standards being development
by the International Imaging Industry Association (i3a.org).
Author: Peter Burns, 12 May 2015
Copyright (c) 2009 Peter D. Burns, pdburns@ieee.org
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