Content deleted Content added
Line 206:
We can understand the arts by looking at a color change or by measuring the surface uniformity change. Since the whole image will be very huge, so we use a double raised cosine window to truncate the image:<ref name="Angelini et al">Angelini, E., Grassin, S. ; Piantanida, M. ; Corbellini, S. ; Ferraris, F. ; Neri, A. ; Parvis, M. FFT-based imaging processing for cultural heritage monitoring Instrumentation and Measurement Technology Conference (I2MTC), 2010 IEEE</ref>
:<math> w(x,y)=\frac{1}{4} \left(1 + \cos {\frac {x \pi}
where ''N'' is the image dimension and ''x'', ''y'' are the coordinates from the center of image spans from 0 to ''N''/2.
The author wanted to compute an equal value for spatial frequency such as:<ref name="Angelini et al"/>
: <math>
:<math> A_m {(f)}^2= \left[\sum_{i=-f}^f \operatorname{FFT}(-f,i)^2+ \sum_{i=-f}^f \operatorname{FFT}(f,i)^2+ \sum_{i=-f+1}^{f-1} \operatorname{FFT}(i,-f)^2+ \sum_{i=-f+1}^{f-1} \operatorname{FFT}(i,f)^2 \right] </math>▼
\begin{align}
A_m(f)^2= \left[ \sum_{i=-f}^f \right. & \operatorname{FFT}(-f,i)^2+ \sum_{i=-f}^f \operatorname{FFT}(f,i)^2 \\[5pt]
▲
\end{align}
</math>
where "FFT" denotes the fast Fourier transform, and ''f'' is the spatial frequency spans from 0 to {{nowrap|''N''/2 – 1}}. The proposed FFT-based imaging approach is diagnostic technology to ensure a long life and stable to culture arts. This is a simple, cheap which can be used in
| |||