## GNU Astronomy Utilities

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#### 8.1.2 If convolving afterwards

In case you want to convolve the image later with a given point spread function, make sure to use a larger image size. After convolution, the profiles become larger and a profile that is normally completely outside of the image might fall within it.

On one axis, if you want your final (convolved) image to be $$m$$ pixels and your PSF is $$2n+1$$ pixels wide, then when calling MakeProfiles, set the axis size to $$m+2n$$, not $$m$$. You also have to shift all the pixel positions of the profile centers on the that axis by $$n$$ pixels to the positive.

After convolution, you can crop the outer $$n$$ pixels with the section crop box specification of Crop: --section=n:*-n,n:*-n assuming your PSF is a square, see Crop section syntax. This will also remove all discrete Fourier transform artifacts (blurred sides) from the final image. To facilitate this shift, MakeProfiles has the options --xshift, --yshift and --prepforconv, see Invoking MakeProfiles.