Decode Runner using EM Algorithm for Coded Aperture Imaging

Scripts

• main

	description
EMdecoderSimple.py	simple imaging
EMdecoderPolarization.py	imaging with polarization

• example

	description
run_simple.py	example to run EMdecoderSimple.py
run_plarization.py	example to run EMdecoderPolarization.py

• cpp

used for drawing image with ROOT.

Main Sequence

1. Set parameters

Use read_pattern_file() and read_encoded_image_txt().

2. Construct matrix

Use construct_matrix.

3. Run

Use run(). E_step() and M_step() are main algorithm.

Parameters and Variables

in EMdecoderSimple.py

parameters need to set is as follows.

	description	example in SPring8_2021B experiment
num_patterns	the number of patterns	8
Ndx,Ndy	the number of detector pixels per pattern	896
Nmx,Nmy	the number of pattern elements per pattern	64
Nsx,Nsy	the number of sky elements	51
mask_pitch	length between pattern elements (um)	35
pixel_pitch	length between detector pixels (um)	2.5
sky_pitch	length between sky elements (arcsec)	20
detector_to_mask	distance from detector to mask (um)	20

variables used in EM Algorithm is as follows.

	description
Mat	matrix from sky to detector
Pattern	mask patterns
EncodedImage	events detected by experiment
detector_X, detector_Y	detector coordinate
sky_X, sky_Y	sky coordinate
S_dist	expected sky destribution
D_dist	expected detector destribution

additional parameters in EMdecoderPolarization.py

	description	example in SPring8_2021B experiment
Ndp	the number of angle	2
angle_pitch	pitch of angle (degree)	90
modulation_factor	modulation factor of detector	0.103..