It is important that the picture has good contrast. Any background that is not important needs to be removed or be very light.
Here are the origninal pictures:
the first was cropped from this larger picture.
The dog face in front of the water is easy to bring out, the other one in front of the rock much harder to do.
I will describe the brown dog, a Vizsla named Logan, first.
First step was to crop.
I used Photoshop, but it could be any picture manipulation software. I selected the body of the dog in front of the water first. Selection does not have to be all that clean.
Then I added a layer with just the selection.
Now I set the opacity of the original layer to about 50%, added a white layer underneath. In this picture the top layer with just the dog body is not visible.
Now the top layer is visible again. The dog has color, the background water is on the second layer with 50% opacity and looks pale.
Now I highlighted the top layer, the one I want to work on, that is the one with the dog body. The selection of the body was not clean, I have to erase the edges.
Next step is to set the contrast in the top layer on very high.
I don't need the color, so change both layers to black and white.
This is the final picture for the Vizsla.
The second dog is a German short hair, named Luke.
Here are the origninal and final pictures:
For Luke I erased all background and made a new layer with a gradient from left bottom to right top.