An image is defined in a DITA document using either an image or fig element. An href attribute on the element is used to reference an external image file.

DITA Compare can be configured to perform a simple comparison (same/different) of images defined in a DITA document. It does this using the following steps:

  1. The xml:base of both input files is used to resolve the href to an absolute location.

  2. The image files at the resolved locations from A and B are then compared.

  3. In the result, markup is added to each element referencing a modified image

Absolute References

The DITA Compare result document may reside in a different location to the inputs. To help view the result where it is output with any image changes, the href attributes in the result can be configured to use absolute references instead of the source document references. This is controlled with the OutputImageRefForm parameter. By default the href value is taken from the source document.

Enabling or Disabling Image Comparison

The image comparison is by default enabled but can be controlled using the ImageCompare parameter.

Please note that DITA Compare do not yet support image comparison of the images referenced using topic refs.