Use of textimage module
Check Textimage 7.x-3.x

It provides a field formatter for long text. Be aware that very large text may create memory issues.

From README.TXT:

via Content Type field display formatters


Access 'Content type' administration features via Administration->   Structure->Content Types
Select the content type for which you want to manage a Textimage field   (e.g. Article, Basic page, etc.)
If you need to create a new field, in the 'Manage Fields' tab, add a new   field of type 'Text' (or 'Long text', or 'Long text and summary') or   'Image'
In the 'Manage Display' tab, select a 'Textimage' format for the field   created above (or any existing one)
Click on the gear icon
Select from the dropdown displayed the image style you want to use to   represent the content as a Textimage