[ITK-users] [ITK] Normalized Cross Correlation returns perfect alignment with images not even overlapping

[Andrew Harris]

In the image mask, the parts we want to include in the calculation are
bright and the parts that we want to exclude are dark, is that the opposite
of what it should be?

--

AH


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On Thu, Mar 30, 2017 at 7:25 PM, Dženan Zukić <dzenanz at gmail.com> wrote:

> Hi Andrew,
>
> your masks might be inverted. If NCC gets all black pixels in both images,
> the correlation will be perfect.
>
> Regards,
> Dženan
>
> On Thu, Mar 30, 2017 at 2:13 PM, Andrew Harris <aharr8 at uwo.ca> wrote:
>
>> Hi, I'm hoping someone can guide me toward an explanation of this.  I run
>> my pipeline on various ultrasound image sets and get an NCC between 0.65
>> and 0.8 for good alignments, but on some sets the NCC returns 1.0 when the
>> images aren't even overlapping.  I have the black areas of the image masked
>> out, and have even tried cranking up the threshold to be sure the darker
>> areas aren't being included to no avail.  Any thoughts?
>>
>> --
>>
>> AH
>>
>>
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