Tracing Images In Revit

Tracing images is a pretty common task in AutoCAD and it is also a common task in Revit. Unfortunately, Revit does not have as many tools for manipulating images as AutoCAD does, but there are some ways to work around these setbacks. You can currently attach BMP, TIF, JPG, and PNG. files to a Revit file. I haven't really seen any real advantage of using one format over another except file size between TIF and JPG. PNG might possibly allow you to have transparent areas. 

Fading Images Back
There is no fading images back in Revit. You will have to darken up the image in Photoshop by adjusting the brightness and contrast of the image before placing the image into Revit. If you change the image while the file is attached you will have to close and reopen the project because there is no reload command.

Locking An Image
There is currently no direct way to lock an image in place in Revit so that it is not accidentally selected. The closest you might be able to get is attaching an image into an AutoCAD drawing and then pinning the AutoCAD drawing in place. I have not tested this method yet. Otherwise, be careful what you select.

There is another trick to selecting objects without selecting the image.  A lot of commands in Revit assume you select the object first and then run the command. If you start the command first, Revit will allow you to use a selection window.

First start the selected command like offset, copy, or mirror.
Second select your objects using a selection window (not crossing).
Third, click on the same command that you started with to activate the command for the selected objects.

Turning An Image On And Off
You might not be able to lock an image in place, nor can you load and unload an image like an xref,  but you can turn an image on and off like a layer.

Go to your visibility graphics (VG) and under the "Model Categories" uncheck the "Raster Image". Keep in mind that visibility graphics are only good for the view you are working in. So they still may show up in other views.

From Drop Box

Difference Between Decal And Image
A Decal is an image that you apply to the surface of an object. You will have to attach an image to the object at insert. An example would be putting an image on a TV set component to make it look like the TV is on.

An Image works like a lot like you think an image should in AutoCAD.

You cannot currently apply an image to topography, because topography is not considered a component.