Devices and methods for obtaining borehole images at a surface installation while a borehole-imaging downhole tool is logging a borehole are provided. One such method may involve, while the downhole tool is disposed in the borehole, obtaining a first borehole image at a first depth of investigation using the borehole-imaging downhole tool. Compression electronics may compress the first borehole image to obtain a first compressed borehole image. Compressing the first borehole image may involve exploiting a symmetry characteristic of the first borehole image to increase compression efficiency or exploiting a similarity of the first borehole image with a second borehole image to increase compression efficiency, or both. The compressed borehole image then may be efficiently transmitted to the surface installation via a telemetry system.