That's really a graphics feature and is used primarily with smaller web-sized images to create text effects (embossed text). It doesn't really have much application to photography. A photo image can be too high res to show much effect.
You're probably missing the blending mode variance between the two layers. To use that function you start with an image on a layer. Next step is to duplicate that layer and apply some edits to the duplicate (at least a gaussian blur). In the Layers dialog is an option for blending modes (Mode). The duplicate layer has to have the blending mode changed (different modes = different effects) try luma for starters. Select the duplicate layer and change the Mode from the drop list. Then select the original image layer and bring up the Bump Map dialog. In the Bump Map dialog click the ? and select the duplicate layer. Set Preview on and you should see changes when you alter the parameters.
That's really a graphics feature and is used primarily with smaller web-sized images to create text effects (embossed text). It doesn't really have much application to photography. A photo image can be too high res to show much effect.
You're probably missing the blending mode variance between the two layers. To use that function you start with an image on a layer. Next step is to duplicate that layer and apply some edits to the duplicate (at least a gaussian blur). In the Layers dialog is an option for blending modes (Mode). The duplicate layer has to have the blending mode changed (different modes = different effects) try luma for starters. Select the duplicate layer and change the Mode from the drop list. Then select the original image layer and bring up the Bump Map dialog. In the Bump Map dialog click the ? and select the duplicate layer. Set Preview on and you should see changes when you alter the parameters.
Ahhh. You know? I didn't quite consider that I wasn't focusing on the photo applicable features. I have scrolled down the GIMP tutorial page and see that there is a specific section for photo editing. I will put this aside for now, and skip to that. Thank you very much though.