> | I have spatially normalized SPECT data encoded on 2 bytes on SPM SPECT
> | Template, and I have noticed that there are some negative values in the
> | resulting normalized data, especially in the borders of the image. Has
> | anyone already noticed that ? Is it possible or may I have made a
mistake
>
> Unless the values have been truncated at zero (not recommended as it
introduces
> bias), your original filtered back-projected images should contain some
negative
> values in the background. If these images are all positive, then spatial
> normalisation may introduce small negative values if you use sinc
interpolation.
> If you have very large negative values, check that the image format you
have
> is fully compatible with SPM.
>
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