**PURPOSE**- Increase resolution of a reconstructed volume using
spherical deconvolution. Output volume has same
size as input volume.

In a reference-based single particle reconstruction an angular assignment is used to determine a projection direction for particle images with the best match to reference projection. Noise and low contrast in electron micrographs leads to uncertainty in angular assignment and blurring of the resulting 3D reconstruction. Spherical deconvolution improves reconstruction quality by reducing blurring and enhancing high frequency components, especially near the periphery of the reconstructed object. Note that this method often does not increase resolution as reported by Fourier ring correlation of sub-set volumes, however actual resolution is improved. Example.

**SEE ALSO****PW**[Power spectrum - Amplitudes of Fourier transform ||] **RO SD**[Rotational average - single line output, doc file]

**USAGE**- .OPERATION: SPH DECON

- .INPUT FILE: VOL001

[Enter name of of file containing input volume.].SIGMA: 30

[Enter the deconvolution angle in degrees. See notes.].OUTPUT FILE: DECVOL001

[Enter name of file where the deconvolved volume is to be stored.]

**NOTES**

- Determine the optimal value of deconvolution angle:
*SIGMA*, by examining deconvolutions with different values of*SIGMA*. The optimal*SIGMA*corresponds to deconvolved volume with the highest high-frequency component in the spacial spectrum. The average amplitude in the 3D Fourier transform spectrum can be calculated using the SPIDER operations: 'PW' and 'RO SD'. - Reference: G. P. Kishchenko & A. Leith,

Spherical Deconvolution Improves Quality of Single Particle Reconstruction. J. Structural Bilogy. (2014) DOI: 10.1016/j.jsb.2014.05.002 - Implemented by G. Kishchenko.

**SUBROUTINES**- SPHDECON

**CALLER**- VTIL3

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