Motivation

Development of this application was stimulated by the discussion with Marcin Sikorski (meeting on 2012-08-30), doing xcs experiments.
Users need in real-time algorithm for calculation of image vs time auto-correlation function

g2(tau) = <I(t)*I(t+tau)> / (<I(t)> * <I(t+tau)>),

where I(t) is an image intensity at time t, and tau is a delay between two measurements.
Typical experimental condition can be described as follows:

• Run duration is about one hour at frequency up to 120 Hz that gives up to 10^5-10^6 images.
• Currently typical imaging devise is a Princeton camera with 1300x1340 pixels.
• Need to calculate g2(tau) for each pixel, averaged over all possible image times t with time difference tau between images.
• A set of tau should have about 30-100 points in log scale uniformly covering the run duration.
• Use for example xcsi0112-r0015: 500 images with 8 sec delay between images.
  Desired time for evaluation of the auto-correlation function should be comparable with run duration <1 hour. Currently this algorithm takes a few hours that can not be used for fast feedback in real time experiment.

Algorithm

Basic idea is (1) to split image vs time for small parts in image, (2) to process each part on separate computer node, (3) to merge results at the end of processing. It is clear that significant speedup (about T/N_nodes_) is achieved at the 2nd stage. These three stages are performed in separate C++ applications. Wrapping python script allows to submit job by a single command. It takes care about file and sub-process management in this job, as described below.

Code location

All modules for this application resides in the package ImgAlgos:

Image splitting

Image splitting is implemented as a regular psana module ImgAlgos::ImgVsTimeSplitInFiles.

Command to run interactively on psana#### or submit in batch from pslogin## node:

psana -c <config-file> <xtc-file-list>
bsub -q psfehq -o log-file 'psana -c <config-file> <xtc-file-list>'

For example:

psana -c ImgAlgos/data/psana-corana.cfg  /reg/d/psdm/XCS/xcsi0112/xtc/e167-r0015-*

where ImgAlgos/data/psana-corana.cfg is an example of the configuration script for psana and /reg/d/psdm/XCS/xcsi0112/xtc/e167-r0015-* are the input xtc files for particular run.

Produces the files:

cor-ana-r0015-b0000.bin - file with a part of image vs time
cor-ana-r0015-b0001.bin
cor-ana-r0015-b0002.bin
cor-ana-r0015-b0003.bin
cor-ana-r0015-b0004.bin
cor-ana-r0015-b0005.bin
cor-ana-r0015-b0006.bin
cor-ana-r0015-b0007.bin
cor-ana-r0015-time.txt - list of time-records for all events in processed run.
cor-ana-r0015-time-ind.txt - list of time-records for all events in processed run with time index.
cor-ana-r0015-med.txt - file with metadata. In particular it has the original image size, number of image parts for splitting, number of images in run, etc.

Algorithms:

• The <int16_t> image data array is split for ordered number of equal parts (by the parameters nfiles_out in psana-corana.cfg file) and each part is saved in the output cor-ana-r0015-b####.bin file sequentially for all selected events.
• The appropriate time record for selected event is saved in the file cor-ana-r0015-time.txt.
• At the end of the splitting procedure:
  • the average time difference and its rms between sequential events is evaluated for all recorded time records.
  • The file cor-ana-r0015-time.txt is re-processed and for each record the time index is evaluated as unsigned value of

    <time-index> = (<event-time> + 0.5 <average-time-between-events>) /  <average-time-between-events>
    

  • Event record with time index is saved in the file cor-ana-r0015-time-ind.txt
• All metadata parameters which are required for further processing, such as input parameters, image size, <average-time-between-events, maximal value of the time index etc., are saved in file cor-ana-r0015-med.txt.

Time correlation processing

ImgAlgos/app/corana application

Command to run interactively on psana#### or submit in batch from pslogin## node:

corana -f <fname-data> [-t <fname-tau>] [-l <logfile>] [-h]
bsub -q psfehq -o log-file 'corana -f <fname-data> [-t <fname-tau>] [-l <logfile>] [-h]'

For example the interactive and batch mode commands:

corana -f cor-ana-r0015-b0001.bin -t my-tau.txt
bsub -q psfehq -o log-file 'corana -f cor-ana-r0015-b0000.bin'

Produce files:

cor-ana-r0015-tau.txt          - string of {{tau}} values for which the auto-correlation function is evaluated
cor-ana-r0015-b0000-result.bin - auto-correlators for the part of the image for all {{tau}} values
cor-ana-r0015-b0001-result.bin
cor-ana-r0015-b0002-result.bin
cor-ana-r0015-b0003-result.bin
cor-ana-r0015-b0004-result.bin
cor-ana-r0015-b0005-result.bin
cor-ana-r0015-b0006-result.bin
cor-ana-r0015-b0007-result.bin

Merging results

ImgAlgos/app/corana_merge application

Command to run interactively on psana#### or submit in batch from pslogin## node:

corana_merge -f <fname-data> [-t <fname-tau>] [-l <logfile>] [-h]
bsub -q psfehq -o log-file 'corana_merge -f <fname-data> [-t <fname-tau>] [-l <logfile>] [-h]'

For example:

corana_merge -f cor-ana-r0015-b0001-result.bin -t my-tau.txt

This procedure produces file:

cor-ana-r0015-image-result.bin

Example of how to get and process results

ImgAlgos/app/corana_procres

Command to run interactively on psana#### or submit in batch from pslogin## node:

corana_procres -f <fname-data> [-t <fname-tau>] [-l <logfile>] [-h]
bsub -q psfehq -o log-file 'corana_procres -f <fname-data> [-t <fname-tau>] [-l <logfile>] [-h]'

Basically it reads files with results and produces the histogram-like table *-hist.txt.

Automatic processing

ImgAlgos/app/corana_submit - is a wrapping script which allows to run all of above procedures by a single command from pslogin## node and it keeps eye on processing of jobs in batch and doing the file management. Command to start:

corana_submit [-c <config-file>] [-t <fname-tau>] [-x] <xtc-file-list>

For example:

corana_submit -c ImgAlgos/data/psana-corana.cfg -t my-tau.txt /reg/d/psdm/XCS/xcsi0112/xtc/e167-r0015-s00-c00.xtc

This script sequentially performs operations for single run as follows:

1. Initialize all parameters
2. Run psana to split image for files
3. Check that all split files are produced
4. Submit job for time-correlation processing
5. Check that all processed files are produced
6. Submit job for merging
7. Check that merged file is produced
8. Submit job for test processing of the file with results
9. List all created files
10. Clean-up files in the work directory
11. List of preserved files

    The next to last procedure deletes all intermediate split- and log- files.
    In debugging mode this procedure may be turned off.

Manual sequential processing

In case of manual processing of all scripts, commands need to be issued in a right order. Commands corana, corana_merge, and corana_procres should have the same list of parameters. This is important, because all file names for these procedures are generated by the same base class ImgAlgos/src/CorAna.cpp

Right sequence of commands to run interactively on psana####

psana -c <config-file> <xtc-file-list>
corana         -f <fname-data> [-t <fname-tau>] [-l <logfile>] [-h]
corana_merge   -f <fname-data> [-t <fname-tau>] [-l <logfile>] [-h]
corana_procres -f <fname-data> [-t <fname-tau>] [-l <logfile>] [-h]

or submit in batch from pslogin## node:

bsub -q psfehq -o log-file 'psana -c <config-file> <xtc-file-list>'
bsub -q psfehq -o log-file 'corana         -f <fname-data> [-t <fname-tau>] [-l <logfile>] [-h]'
bsub -q psfehq -o log-file 'corana_merge   -f <fname-data> [-t <fname-tau>] [-l <logfile>] [-h]'
bsub -q psfehq -o log-file 'corana_procres -f <fname-data> [-t <fname-tau>] [-l <logfile>] [-h]'

The corana batch jobs can be submitted and run on separate butch nodes in parallel. All other procedures can be submitted when previous is successfully finished and all necessary files are produced.
The corana_procres command is optional and is currently used for test purpose only. But, it may be replaced by real analysis code.

File formats

• File with split-image data for selected events cor-ana-r0015-b000N.bin:
  Currently this file contains <uint16_t> amplitude for each pixel in binary format for:

  <data-for-img-partN-of-img1> <data-for-img-partN-of-img2> ... <data-for-img-partN-of-imgLast>
  

• File with metadata parameters cor-ana-r0015-med.txt:

  IMAGE_ROWS      1300
  IMAGE_COLS      1340
  IMAGE_SIZE      1742000
  NUMBER_OF_FILES 8
  BLOCK_SIZE      217750
  REST_SIZE       0
  NUMBER_OF_IMGS  500
  FILE_TYPE       bin
  DATA_TYPE       uint16_t
  TIME_SEC_AVE    8.088413
  TIME_SEC_RMS    0.063639
  TIME_INDEX_MAX       499
  

• File with image time records cor-ana-r0015-time.txt:

       1        0.000000  0.000000  20120616-080236.671607864    5366      0
       2        8.026429  8.026429  20120616-080244.698036743    8255      1
       3       16.144788  8.118359  20120616-080252.816395836   11177      2
       4       24.154835  8.010048  20120616-080300.826443448   14060      3
      ...
  

  where each record has:

  <image-in-file#> <t(sec)-from-the-1st-event> <dt(sec)> <time-stamp> <fiducials> <event#-since-configure>
  

• File with image time records and evaluated time index cor-ana-r0015-time-ind.txt:

       1        0.000000  0.000000  20120616-080236.671607864    5366      0        0
       2        8.026429  8.026429  20120616-080244.698036743    8255      1        1
       3       16.144788  8.118359  20120616-080252.816395836   11177      2        2
       4       24.154835  8.010048  20120616-080300.826443448   14060      3        3
       5       32.281937  8.127102  20120616-080308.953545010   16985      4        4
      ...
  

  where each record has:

  <image-in-file#>  <t(sec)-from-the-1st-event> <dt(sec)> <time-stamp> <fiducials> <event#-since-configure> <time-index-starting-from-0>
  

• File with split-image correlators for each value of tau cor-ana-r0015-b000N-result.bin:
  Currently it saves <float> correlator for each pixel in binary format for:

  <corr-for-img-partN-of-tau1> <corr-for-img-partN-of-tau2> ... <corr-for-img-partN-of-tauLast>
  

• my-tau.txt:

   1 3 5 7 9 10 12 14 16 18 20 24 28 30 32 36 40 ... 160 180 200 240 280 300 320 360 400
  

  contains the tau values presented in terms of number of ordered images in the file.

Quick start guide

We assume that everything is set up to work on LCLS analysis farm, otherwise see Computing (including Analysis) and Account Setup.

How to run this procedure

If the version of the package ImgAlgos is available as a current software release, then you may run the script command(s) directly, for example:

cd <your-favorite-directory>
mkdir work_corana
sit_setup
corana_submit [-c <config-file>] [-t <fname-tau>] [-x] <xtc-file-list>

cd <your-favorite-directory>
newrel ana-current myReleaseDirectory
cd myReleaseDirectory
sit_setup
addpkg ImgAlgos HEAD
scons

Where to find results

The procedure will produce a bunch of files in the work_corana directory. If everything is OK, then all spit - and log- files will be removed at the end of automatic corana_submit procedure. The most important files are preserved for further analysis:

How to look at results

It is assumed that all files listed in previous section may be used for further analysis, depending on particular goals. The optional script corana_procres is designed as an example of how to access data from C++ code. Class CorAnaProcResults produces the file *-hist.txt
A simple python script shows how to plot this file:

./ImgAlgos/data/PlotCorAnaResults.py work_corana/cor-ana-r0015-hist.txt