In my previous article I showed how you could improve the quality of the pictures that you made under water by following a few simple guidelines and by simple editing. In this article I will show you that you can get even better pictures by applying more advanced editing techniques. I am using Photoshop CS5 with adjustment layers for non-destructuve editing. I am aware of the fact that GIMP doesn't have adjustment layers. Although not equivalent an option in GIMP is to duplicate the most recent layer for each step to apply the next step to. As said, not the same as an adjustment layer, but at least you are able to go back a step if you need to. The biggest problem with this approach is that you have to redo your steps if you decide that an effect in one of the previous layers is not exactly right.
This is the image after applying a white balance correction in the RAW editor. The same starting point could be reached by working with custom white balance under water as explained in my previous article. The image is still quite green and has a low contrast.
There were a few distracting elements in the original picture so I created a new layer in which I used the clone tool to remove these elements. If you look closely to the two images above you will see that the fish in the top right corner in the upper image is gone in the lower image and that some spots have been removed.
The next step is to add an adjustment layer for levels. Levels is a nice tool to get the color corrected. Adjust the histogram for each of the 3 basic colors (Red, Green Blue) by moving the right and left slider till it touches the end respectivily starting point of the actual histogram. In this way the pixels present in the picture for that particular color will be stretched from black to white. By doing this for each of the colors you get a much improved color in the picture as a whole. You can tweak it a bit by adjusting the endpoints slightly or by adjusting the middle slider. This works best for the color Red because that is the color that is mainly missing under water. The image above shows the result that I got with this adjustment layer. A much more natural looking scene. Normally I would stop here. The remaining steps are minor tweaks.
First I increased the contrast a little by adding a curves adjustment layer. The curve is a slight S-curve as you can see in the image above. The curve has two points. One in the lower left corner which basically takes care of keeping the shadows from becoming darker. The second point makes the midtones brighter and also increases the highlights a bit. The contrast in the lower midtones is increased a bit by this curve. The result can be seen in the image below:
Especially the school of Schoolmasters in the middle of the picture is much more pronounced by this change. Also the coral in the foreground is brighter.
If you look closely at the image there are two things that could be improved. The color of the water in the background could be a bit more blue and the finger coral and soft coral in the foreground is still a bit greenish where it should have been more yellow. Both can be corrected by adjusting the Hue. That is what I did in the next two adjustment layers. First I created an adjustment layer for Hue/Saturation and clicked with the dropper in the top-left corner of the adjustment window on the blue of the backgrount to select the exact current color of the water. Then I moved the slider for Hue a bit to the right towards a more real blue color. It is a small correction of only +7. Nothing changed in the saturation or lightness sliders. See the adjustment window below:
The resulting image is:
It makes almost no difference but I like this blue a bit better than the one without the correction.
Next comes the correction of the greenish coral. To do that I created another adjustment layer for Hue/Saturation. This time I used the dropper to get the current color of the soft coral in the foreground. I moved the Hue slider 15 points to the left (-15) to get the right hue for the coral. See the adjustment window below:
Also here no change to Saturation or Lightness. The resulting image:
That was my last step. The picture has been improved a lot from the original greenish one with low contrast to one with natural looking colors and sufficient contrast where the Schoolmasters in the middle are much more pronounced.
Below in a larger version the pictures as a result of each step.
If you want to download the PSD-file with all the layers you can do so by clicking on this link. You can open this PSD in Photoshop and look for yourself which layers I used and what correction I applied.
I learned a lot from the tutorials provided by David J. Nightingale at Chromasia. Take a look for yourself by clicking on the link. There is a free tutorial regarding curves; other tutorials require a yearly fee. But that fee is certainly worth the money.
The original image; only corrected for white balance in RAW-editor
Distracting elements removed (fish upper right, some spots to the left)
Levels adjustment layer to correct the colors overall
Curves adjustment layer to increase contrast in the lower midtones and brighten the highlights a bit
Small correction with Hue/Saturation adjustment layer for the blue water
Small correction with Hue/Saturation adjustment layer for the yellow in the coral
