Multiscale structural similarity (MS-SSIM) index for volume quality

calculates the MS-SSIM index, `score`

= multissim3(`V`

,`Vref`

)`score`

, for volume `V`

,
using `Vref`

as the reference volume.

The structural similarity (SSIM) index measures perceived quality by quantifying the
structural similarity between a volume and a reference volume (see `ssim`

). This function calculates the multi-scale structural similarity
(MS-SSIM) index by combining the SSIM index of several versions of the volume at various
scales. The MS-SSIM index can be more robust when compared to the SSIM index with regard to
variations in viewing conditions.

`[`

also returns the local MS-SSIM index value for each pixel in `score`

,`qualitymaps`

] = multissim3(`V`

,`Vref`

)`V`

, and
each of the scaled versions of `V`

. The `qualitymaps`

output is a cell array containing maps for each of the scaled versions of
`V`

, with each quality map the same size as the corresponding scaled
version.

`[`

specifies options using one or more name-value arguments. The options control aspects of
the computation. For example, use the `score`

,`qualitymaps`

] = multissim3(`V`

,`Vref`

,`Name,Value`

)`'NumScales'`

argument to specify the
number of scaled versions.

The `multissim3`

function uses double-precision arithmetic for input
volumes of class `double`

. All other types of input volumes use
single-precision arithmetic.

[1] Wang, Z., Simoncelli, E.P.,
Bovik, A.C. *Multiscale Structural Similarity for Image Quality
Assessment*. In: The Thirty-Seventh Asilomar Conference on Signals, Systems &
Computers, 2003, 1398–1402. Pacific Grove, CA, USA: IEEE, 2003.
https://doi.org/10.1109/ACSSC.2003.1292216.