[Insight-developers] Calculators: Buffered or Requested regions?
Miller, James V (Research)
millerjv at crd . ge . com
Thu, 12 Jun 2003 11:29:34 -0400
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I was just looking through some of the calculators. The
MinimumMaximumImageCalculator performs its calculation across the
RequestedRegion. The OtsuThresholdImageCalculator performs its calculation
over the BufferedRegion.
So there is an inconsistency here. Besides the inconsistency, the Otsu
method uses the MinimumMaximum to determine how to build its own histogram.
So the range of values for its histogram is based on the pixels in the
RequestedRegion but it determines a threshold from the histogram based on
the BufferedRegion. This inconsistency could bias the threshold calculated.
At a minimum, I would think the calculators should be consistent. I could
make a case for either region being appropriate (more than I want to get
into here). Perhaps the calculators should take a region over which to
perform the calculation?
Jim Miller
_____________________________________
Visualization & Computer Vision
GE Research
Bldg. KW, Room C218B
P.O. Box 8, Schenectady NY 12301
millerjv at research . ge . com <mailto:millerjv at research . ge . com>
james . miller at research . ge . com
(518) 387-4005, Dial Comm: 8*833-4005,
Cell: (518) 505-7065, Fax: (518) 387-6981
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<DIV><FONT face=Arial size=2><SPAN class=611072315-12062003>I was just looking
through some of the calculators. The MinimumMaximumImageCalculator
performs its calculation across the RequestedRegion. The
OtsuThresholdImageCalculator performs its calculation over the
BufferedRegion.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=611072315-12062003></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=611072315-12062003>So there is an
inconsistency here. Besides the inconsistency, the Otsu method uses the
MinimumMaximum to determine how to build its own histogram. So the range
of values for its histogram is based on the pixels in the RequestedRegion but it
determines a threshold from the histogram based on the BufferedRegion.
This inconsistency could bias the threshold calculated.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=611072315-12062003></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=611072315-12062003>At a minimum, I
would think the calculators should be consistent. I could make a case for
either region being appropriate (more than I want to get into here).
Perhaps the calculators should take a region over which to perform the
calculation?</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=611072315-12062003></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><STRONG><SPAN style="COLOR: navy; FONT-FAMILY: 'Comic Sans MS'">Jim
Miller</SPAN></STRONG> <BR><B><I><SPAN
style="FONT-SIZE: 10pt; COLOR: red; FONT-FAMILY: Arial">_____________________________________</SPAN></I></B><BR><EM><SPAN
style="FONT-SIZE: 7.5pt; COLOR: black; FONT-FAMILY: Arial">Visualization &
Computer Vision</SPAN></EM><I><SPAN
style="FONT-SIZE: 7.5pt; COLOR: black; FONT-FAMILY: Arial"><BR><EM>GE
Research</EM><BR><EM>Bldg. KW, Room C218B</EM><BR><EM>P.O. Box 8, Schenectady NY
12301</EM><BR><BR></SPAN></I><EM><U><SPAN
style="FONT-SIZE: 7.5pt; COLOR: blue"><A
href="mailto:millerjv at research . ge . com">millerjv at research . ge . com</A></SPAN></U></EM></DIV>
<DIV>
<P style="MARGIN: 0in 0in 0pt"><EM><U><SPAN
style="FONT-SIZE: 7.5pt; COLOR: blue">james . miller at research . ge . com</SPAN></U></EM><BR><I><SPAN
style="FONT-SIZE: 7.5pt; COLOR: black; FONT-FAMILY: Arial">(518) 387-4005, Dial
Comm: 8*833-4005, </SPAN></I><BR><I><SPAN
style="FONT-SIZE: 7.5pt; COLOR: black; FONT-FAMILY: Arial">Cell: (518) 505-7065,
Fax: (518) 387-6981</SPAN></I> </P></DIV>
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