gaussf: different boundary behaviour within methods

[AndreZeug]

Component
Matlab R2024a
DIPimage toolbox for quantitative image analysis
Version 3.4.3 10-May-2024

Describe the bug
The methods included in gaussf (derivative) lead to different boundary behaviour, depending on method used.
When smoothing a z-stack structures from the last/first layer are present in the first/last - depending on the method used.

RAW z0

iir z0 (ddiir = single(gaussf(double(squeeze(dd)),[.8 .8 .8],'iir'));)

ft z0 (ddft = single(gaussf(double(squeeze(dd)),[.8 .8 .8],'ft'));)

Question
Can 'boundary_condition' , 'truncation' be used with 'ft' to achieve similar behaviour as with 'iir' and 'fir'?
Typically I use a weak smoothing of 0.5 which implicates 'ft' method as default.

To Reproduce
Sample data can be found here dd_uint8.zip.

ddiir = single(gaussf(double(squeeze(dd)),[.8 .8 .8],'iir'));
ddft = single(gaussf(double(squeeze(dd)),[.8 .8 .8],'ft'));
ddfir = single(gaussf(double(squeeze(dd)),[.8 .8 .8],'fir'));

System information:
Win10, Matlab2024a, DIPimage 3.4

[crisluengo]

I agree, this should be consistent. I’ll have to take a look how to do this properly, we also don’t want to change behavior that people might depend on.

[AndreZeug]

Dear Chris,
Thank you so much!
You are faster with fixing then I with compiling 🙈
Both conditions work perfect now! (at least for me 🤭)

Best, Andre