Name

recons3d_nn_SSNR - calcuate signal noise ratio & variance of 3D reconstruction using nearest neighbor interpolation.

Usage

• [ssnr, vol_ssnr] = recons3d_nn_SSNR(stack_name, list_proj, symmetry, npad, snr, sign, w, filename)

Input

stack_name

Name of the file with projection data

list_proj

Index of the projection which will be utilized

ctf

flag for turning on ctf SSNR calculation. In order to correct ctf, ctf SSNR calculation would first calculate 3D Wiener summation of all the raw images, and then calculate SSNR.

symmetry

Point group of the target molecule, default to "c1"

npad

Times of padding to be applied, default to be 1

snr

signal noise ratio of the image, used for ctf SSNR calculation.

sign

sign of ctf.

w

The thickness of the shell, default to be 1

filename

The filename in which you wish to store the SSNR value, default to be None

Output

1. 3D reconstructed volume image.
2. ssnr file with 3 columns: 1. frequencies; 2. signal noise ratio; 3. variance; 4. number of images. 5. radius square
3. outlist: a list containing two columns: 1. frequencies 2. variances
4. vol_ssnr: SSNR 3D volume,which is real and has Fourier volume dimension. It can be multiplied to Fourier volume.

Description

1. Weighted nearest neighbour algorithm is used in the 3D reconstruction of SSNR calculation.
2. ctf SSNR requires that the images are not pre-multiplied by ctf.

Method

Reference

Author / Maintainer

Zhengfan Yang& Zhong Huang

Keywords

category 1

INVERSION

category 2

FOURIER

Files

reconstruction.py

See also

Maturity

stable

works for most people, has been tested; test cases/examples available.

Bugs

None. It is perfect.