embed object ID into photos as a watermark

[EuropaxEarth]

As the subject title suggests I'm attempting to embed the "objectID" into each photo as a watermark so that when that photo is downloaded as a report, the ObjectID will be visible.

I've been referencing the following document for help: https://community.esri.com/t5/arcgis-survey123-blog/survey123-tricks-of-the-trade-photo-watermarks/b...

I think I could create a new field, text type question for ObjectID. But since ObjectID is an Auto-increment field, I assume there's another approach I've failed to consider. 

Many thanks,

EuropaxEarth

[EuropaxEarth]

Based on your recommendations and this esri blog post  

 I created a new integer datatype to return an integer reflecting the index in the repeat. In the calculations field I put in the following function: 

position(..)

^ which returns the index of the current record in a repeat

Then I created a new calculate datatype. I need this to create a watermark ( it doesn't appear in the survey. It is very similar to a hidden question.) Under the calculation field, I did the following:

concat("Photo ", ${photo_num}, "&color=red&outlineColor=black&haloColor=white&size=26&bold=true")

Finally, under the existing image datatype, I scrolled over to the calculation field and typed in:

bottomLeftWatermark=${watermark} watermark="Lat: @[Latitude] \n Lon: @[Longitude]&color=red&outlineColor=black&size=26&bold=true&margin=10"

This creates two watermarks: the photo number and the coordinate point. 

Thank you both for your assistance!