When you save HTML code containing an image tag in a Multiple Lines of Text column, and you've integrated the list or library with a SmartForm, the image doesn't display.
When SharePoint saves the HTML code with an image tag, it removes your absolute URLs and makes them relative to the SharePoint site. SmartForms are hosted on the K2 server which, because it has a different URL than the SharePoint server, cannot render the image in the SmartForm.
The Rich Text control is used on the SmartForm and will correctly show and edit HTML it is provided. To prevent SharePoint from changing absolute URLs into relative ones, change the text mode on the column in SharePoint. The below example illustrates the issue and solution.
SharePoint cannont render the HTML in a list view when the Multple Lines of Text column is configured in Plain Text mode. The below example illustrates the issue and solution.