The photo above is of an opalescent sea slug (Hermissenda crassicornis). This is the first marine species that I have featured on this blog—which is a little surprising given that I am technically a marine biologist. Opalescent sea slugs are a common species of nudibranch on the West Coast of North America and range from Alaska to Baja, Mexico. They reach about two inches (five centimetres) in length and feed on hydroids, tunicates, sea anemones and other marine invertebrates.
I took the picture more than 20 years ago as it was creeping upside-down under the surface of the water in a small aquarium. I think it’s a nice picture of a very pretty animal. And it’s an interesting photo too as you normally see these critters from above. The original image was shot on Fujichrome 50 slide film and I recently had the slide scanned and digitized. The original scanned version is shown below. As you can see, it needed some serious editing…
As always, there was some quality lost via the scanning process. However, the original image also had some problems: the water had a lot of debris and particulate matter which are really obvious in the background; and there were a couple of bad reflections on the surface of the water. I think the main reflection is of the overhead fluorescent lights. Between the debris and reflections, this isn’t an image that would have likely used for anything back when I took it. I kept it though because it was a nice photo of the animal itself.
The first thing I did once after opening the image with Photoshop Elements 8.0 was to tweak the contrast a bit. Then I needed to deal with the background, and I discovered a neat way to do it by following these steps:
- I selected the “Selection brush tool” on the left-hand side.
- I then zoomed –in on the image, and carefully used the tool to select all of the sea slug, but not the background. This was a time consuming process. But it was made easier by the fact that the animal had smooth lines and no fine surface detail.
- Once the animal was selected, I clicked on the “Select” menu at the top of the page, and then chose “Inverse”; which means I had now selected everything EXCEPT the animal.
- I then clicked on the “Filter” menu, chose “Blur” and then “Average”, and voila!
The final result (at the top of the page) is a nice picture of a opalescent sea slug set against a clean, out of focus background that looks quite natural. Not only did I significantly improve the quality of a scanned image, I also salvaged a picture that had critical flaws in its original form.
The technical stuff:
Camera: Olympus OM-4 SLR
Lens: Tamron 90mm F2.5 macro lens
Settings: F16 @ 1/60 sec
Lighting: Vivitar 283 with vari-power module
Film: Fujichrome 50 ASA