The Rock below is a custom job I did for someone who wanted to give a special rock to a wedding couple to commemorate their special day. Although I've painted portraits in the past, I felt that because of the size of the rock, that decoupage would be the best solution to get the exact imagery one would want as a keepsake.
The process is fairly simple, although it has to be said that having Adobe Photoshop™ or Affinity image editing programs are necessary for getting the desired results. Now, Get on the computer. but before starting to modify your picture, make sure you have a perfectly flat, dried, painted rock with a color that offers enough contrast to make your image compatible with the rock.
Now, after scanning and/or opening a .jpg or .tiff file, you begin to modify the image accordingly ( i.e. create the shape and physical size of the image you want ) This can best be served by increasing the resolution of the images to 300dpi which will produce a suitable printout. You can give the picture a certain shape, clarity, text addition or flourish to make for visually pleasing output. The physical size of the photo below is approximately 3.5"X 2.5" after all the changes that were made.
The next step is to output the image to your inkjet printer. The paper should be glossy, and preferably sticky-back. The next step is to cut the image out and place it on the Flat, oblong, symmetrical, smooth rock in such a way that leaves a 1/8 " border all the way around the image. When adhering (or gluing E6000™) the picture to the rock, make sure it lies flat and does not buckle. This can be achieved by pressing and holding the picture onto the rock for about a minute. Lastly, when the glue is dry, clear-coat the image with either Triple Thick™ or Duraclear™. This will protect the picture and still retain the high gloss finish. The puff paint and glitter as a border adds a nice finishing touch. Voila! You now have a beautiful commemorative gift rock.