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<p>Javier,</p>
<p>I've just advertized bilinear.</p>
<p>For average_mp vs average_magphase, they are indeed different
code paths.</p>
<p>My understanding of the code is that:</p>
<p>- average_magphase is only available for the complex data types<br>
</p>
<p>- for the complex data types, average_magphase makes sure that
the norm of the output pixel is the average of the norms of the
contributing input pixels, for each pixel. Whereas average_mp
(according to 4d678d358354497813c2933ad1c18a924a3859e3, this
stands for Magnitude Preserving averaging) does first standard
averaging on the real and imaginary parts, but then multiply both
components by gain = standard_deviation_of_input_band /
standard_deviation_of_overview_band_before_correction.</p>
<p>- average_mp is also available for the non-complex data types,
but then it modifies the output pixels such that output_pixel =
(output_pixel_before_correction -
mean_of_overview_band_before_correction) * gain +
mean_of_input_band.</p>
<p>Feel free to experiment a bit to confirm my reading, and provide
doc enhancements. As far as I can see, there is zero regression
testing of those 2 methods (they date back to 2001, not sure the
autotest framework was available at that time).<br>
</p>
<p>Even<br>
</p>
<div class="moz-cite-prefix">Le 23/07/2024 à 10:57, Javier Jimenez
Shaw via gdal-dev a écrit :<br>
</div>
<blockquote type="cite"
cite="mid:CADRrdKspEgMBuVdmC=9A-0jaq1e7QMGeaqCP73CxRSkY8GyTFw@mail.gmail.com">
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<div>Reading carefully <a
href="https://gdal.org/programs/gdaladdo.html"
moz-do-not-send="true" class="moz-txt-link-freetext">https://gdal.org/programs/gdaladdo.html</a></div>
<div>I saw that the summary mentions</div>
<div><br>
</div>
<div>[-r
{nearest|average|rms|gauss|cubic|cubicspline|lanczos|average_mp|average_magphase|mode}]</div>
<div><br>
</div>
<div>but later in the options "bilinear" is included. Either it
should be in both or in none.<br>
</div>
<div><br>
</div>
<div>In addition to that, in the summary there are
"average_magphase" and "average_mp", but in the later
description, only average_magphase. It is not clear if they
are the same or different. Looking at the code I think they
are not the same thing.</div>
<div><br>
</div>
<div>Should that be changed? if yes, how?</div>
<div><br>
</div>
<div>Cheers</div>
<div>Javier<br>
</div>
<div>
<div>
<div dir="ltr" class="gmail_signature"
data-smartmail="gmail_signature">
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<div>.___ ._ ..._ .. . ._. .___ .. __ . _. . __.. ...
.... ._ .__</div>
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</div>
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<br>
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</blockquote>
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