You can label and caption various category of objects - an inline image, a table, a LaTeX fragment or a Math formula - using ‘#+LABEL’ and ‘#+CAPTION’ lines. See (emacs)File Archives. ODT exporter enumerates each labeled or captioned object of a given category separately. As a result, each such object is assigned a sequence number based on order of it’s appearance in the Org file.
In the exported document, a user-provided caption is augmented with the category and sequence number. Consider the following inline image in an Org file.
#+CAPTION: Bell curve #+LABEL: fig:SED-HR4049 [[./img/a.png]]
It could be rendered as shown below in the exported document.
Figure 2: Bell curve
You can modify the category component of the caption by customizing the variable ‘org-odt-category-strings’. For example, to tag all embedded images with the string ‘Illustration’ (instead of the default ‘Figure’) use the following setting.
(setq org-odt-category-strings '(("en" "Table" "Illustration" "Equation" "Equation")))
With this, previous image will be captioned as below in the exported document.
Illustration 2: Bell curve