How to edit your underwater photos with the free editor Gimp

Following my “Underwater Photography 101” blog post which aim was to show the basic techniques to improve your underwater pictures, I want to give you more details on how to put the final “wow” touch. Even if you couldn’t manage to shoot beautiful and sharp pictures, my image editing routine can save your underwater memories.

Even if you couldn’t manage to shoot beautiful and sharp pictures, my image editing routine can save your underwater memories.

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Using the free image editing software Gimp, follow my step by step tutorial to improve your underwater picture in almost no time. First, you can download this software for free

Download Gimp for free here

Below, you can click on my original clownfish picture to download it. Once the software has been installed, start it and open the file of the clownfish picture.

original clownfish picture

1 – Crop your picture to improve the composition

Removing some uninteresting parts of the picture or creating a more interesting composition by decentring your main subject following the rule of thirds will dramatically improve your image. Use the cutter tool in the toolbox, click on your picture and while holding your mouse, extend to the borders of your picture. From there, you can start cropping your picture while respecting the proportions. Once you have defined a new frame you can also move it around to centre or decentre your subject as you wish. Press Enter and you picture is cropped, looking more like a professional shot.

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2 – Use the magic auto levels tool

This one is the magic trick for underwater pictures. It doesn’t work 100% of the time, but I would say a good 80%. In the top menus, go to “Color” and then select “Levels”. Tick the Preview option, and simply click on the Auto button! The difference is stunning! In the case of this picture, unfortunately, as the clownfish is orange/red, it saturates too much of its colour so we will need to desaturate a little with the other tools. When your subject has no bright colours such as red or orange, the result of using the next tools will be to add more striking contrast and enhance colours with saturation.

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gimp levels tool

3 – Adjust the colour balance

In the “Color” menu, select “Color Balance”. This one is the perfect complement to the previous levels tool when it compensated too much on one type of colour. Readjust the balance Cyan/Red, Magenta/Green and Yellow/Blue. Thanks to the preview option, you can easily make different trials until you find the right setting.

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4 – Control the saturation

In the “Color” menu, select “Hue – Saturation”. In the case of my clownfish picture, I decrease the saturation of the yellow and red colours, I also add lightness to make the colour more transparent. To emphasise the tips of the anemone, I decided to add some saturation on their blue colour, but here this is only a personal artistic choice.

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5 – Discover the power of the “Curve”

This tool is one of my favourite ones. Ideal when you have very bright parts in a picture with very dark parts. In the “Color” menu, select “Curves”. By simply clicking on the graph, you can change the shape of the curve. The darkest colours are on the left side and the brightest colour on the right. Here I decrease the white for the stripes of the clownfish that were too bright. I also very often get the dark colours darker as a way to increase the contrast without saturating the colours.

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6 – Final Brightness/Contrast adjustments

I always prefer to use this tool at the end if the picture needs a final overall adjustment. I sometimes don’t need to use it after the curve tool, if the shot was quite good already from a light and contrast point of view. In the “Color” menu, select “Brightness-Contrast”. The best, once more, is to play with the settings using the preview to check how more or less of each can improve your picture.

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7 – Save your work

You can now save your picture in any format you like by selecting “Export as” in the “File” menu and share it on your favourite social media platform to show off a little!

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Here is the result compared to the original. It’s surprising that in so few steps you could get such a big improvement!

Adjusting the levels, colours and contrast change dramatically the picture

Adjusting the levels, colours and contrast change dramatically the picture


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Underwater Photography 102 Edit your photos with Gimp for free in 30 secsBest free editing software underwater photos


Posted by Florine

  1. […] about enhancing your digital underwater pictures, please visit this excellent post by World Adventures Divers. The basic editing is universal and applicable to most photography […]


  2. Hello Florine, this is DIrk Jay from FB, have you tried the following script for gimp ?
    i think the results are really good :

    keep writing 😉


    1. No I haven’t, it’s a specially optimised script for uw pics? I need to try that! will let you know!


  3. Hi Florine, do you know how to get similar improvements on video files? I’ve got some from recent dives in Indonesia but can’t edit them in gimp. Hope you can help


    1. Hi Alistair! I use AVS video editor and I can do some corrections but not as good as what GIMP can do. If you want good corrections on your video, I guess Adobe Premiere Elements could be a way to go, not as expensive as Abode Premiere (for the pros) but still not cheap. Anyway, thank you for this new post idea, I will look into it! 😉


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