You can use PI markers in your DITA document to assign a property to a single graphic or to only a few graphics, or to exclude a graphic from a general assignment. Use either of these PI marker types:
HTMConfig for individual graphics
Insert the HTMConfig PI marker in text before the graphic, and provide as marker content the property assignment. For example, to scale a certain graphic to 75%, you could place an HTMConfig PI marker just before the <image> tag, and specify the scale factor as the PI marker content:
See §42.2.9.4 Overriding graphic properties for HTML.
HTML Macro for a series of graphics
You can use PI markers of type HTML Macro to change the value of a macro variable just before a graphic or series of graphics, then change it back again after the graphics. For example, you could use HTML Macro PI markers and a macro variable to scale a series of graphics to 75%.
Include in the configuration file a scale-factor setting that references a macro variable:
Initialize the value of the macro variable:
In text just before the graphics to be scaled, insert an HTML Macro PI marker with content:
Just after the graphics to be scaled, insert another HTML Macro PI marker with content: