Modeling the Histogram
of the Halftone Image to Determine
the Area Fraction of Ink
Sum of Two Gaussians Algorithm developed in MathCad
Equivalent Straight Edge Algorithm developed in MathCad
define the edge that represents the bimodal image.
makes the edge reflectance versus position, x, from 0 to 1.0, with points
defined in equal intervals of x. We want to define the edge in equal
intervals in terms of r, and turn it on its side.
Next we take the derivative of the xx versus rr function.
The result is a histogram corresponding to the edge image. Note the sharpness of the peaks.
we add noise (RMS granularity) to the image.
noise is modeled as a gaussian function and then convolved with the histogram.
end up with a phase shift.
fix this by shifting the histogram.
The FFT and inverse FFT process lost one element from the h2 vector of data. We artificially restore it so we can use the "linterp" function to match the data and the model.
read in a histogram.
we normalizethe measured histogram to unity.
normalize the model to unity and compare the model to the data.
we calculate the differece
Table of Contents|Thesis