Or you can now decide to make this cracks layer into an alpha channel and apply it as a Lighting Effects texture channel adding a 3D feel to your image.

To turn this crack layer into an alpha channel make sure the cracks layer is the topmost layer in the Layers palette, layer mode is set to Normal and layer opacity is set to 100%. Go to the Channels palette and while holding down the Ctrl key left mouse button click the Red channel. This will select all the white areas. To invert this selection so that only the cracks are selected: Hold down Ctrl+Shift and press "I". Now the cracks are selected and the "Save selection as channel" icon will turn on at the bottom of the Channel palette…a little square with a circle in it…click on this icon to make the selection an alpha channel.

Ctrl+D to deselect, Make a copy of your base image and you can safely apply a Lighting Effects filter using the alpha channel as the texture channel in the filter. Since these are cracks and therefore pitted into the image, it is better that you leave "white is high" unchecked and set the height to 1 or there about.

To add further depth to the cracks you can utilize the crack layer in the Layers palette by setting it to Multiply mode and set opacity to about 10% on top of the Lighting Effects rendered image.

You can merge these two layers and change layer mode to Soft Light. Since it now hovers as a separate layer over your untouched base image you can further manipulate by erasing further anything you might find distracting allowing the base image to show through. When satisfied you can flatten your image.

As an aside, steps 9-12 above can also be used to create veins and lightening effects by manipulating the Threshold adjustment.

Quest