Experimental Physics and
Industrial Control System

Mark Rivers via Tech-talk <tech-talk at aps.anl.gov> · Wed, 5 May 2021 12:26:04 +0000

Hi LiangChih,

> I know PV ArrayData contains the image data, however, it seems there is other kind of data .

The ArrayData PV contains only the image data, nothing else. Because of the limitations of EPICS Channel Access it is not "self-describing", you need to use other PVs in NDPluginStdArrats to determine:
- The X and Y dimensions of the image
- The actual datatype
- The color mode

Your waveform record must have its datatype (.FTVL) at least large enough to hold the image datatype.  In your case you have UInt16 data.  Because Channel Access does not directly support unsigned data types you must either:
- Use FTVL=SHORT (i.e. Int16) and then cast the data to UInt16 in your Channel Access client
- Use FTVL=USHORT which is actually Int32

What are you seeing that makes you think that ArrayData contains something in addition to the image data?

Mark

From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Chiang, Liang-Chih [江良志] via Tech-talk <tech-talk at aps.anl.gov>
Sent: Wednesday, May 5, 2021 2:08 AM
To: tech-talk at aps.anl.gov
Subject: Where is the image data in PV ArrayData of areaDetector Plugin NDPluginStdArrays?

Hi, EPICS mates,

I use EPICS module   areaDetector to access  a   GigE Camera   (  Allied Vision Manta G-032B),
there is no problem so far. 

CSS screenshots:
https://ibb.co/nQ0cY17
https://ibb.co/2gWWt1x

I know PV ArrayData contains the image data,
however, it seems there is other kind of data .

After reading some documents of NDArray and   plugin NDPluginStdArrays,
I still don't know how to interpret ArrayData.

Where is the raw image data in ArrayData?

Best regards.

LiangChih Chiang
Beamline Group
NSRRC
email：chiang.lc at nsrrc.org.tw 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System