Professional Skin Retouching in GIMP

In this tutorial I will show you how to use the ‘Frequency Separation’ method for professional skin retouching in GIMP. GIMP is free to download and use on Windows, Mac & Linux systems, and is a good alternative to Photoshop. Download it here.

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Let me preface this tutorial by saying that this is not a technique I use in my everyday editing. Fine lines, pores, freckles, skin pigmentation – they are natural, and I do not consider them to be unsightly ‘blemishes’, but rather signs of being human. That said, I am providing this tutorial as there are times when skin retouching is necessary. For example, in wedding photography a bride may have heat rash on her face and neck from nerves leading up to the ceremony; a client may have severe acne scarring that they are self conscious about and would prefer not to have feature in their portrait photographs; you may have recently been on holiday to somewhere hot and humid and succumbed to more than your fair share of mosquito bites (this happened to me recently – I counted more than 50 bites on my legs alone!); or perhaps your subject was simply tired and has dark circles under his or her eyes. There are many reasons for choosing to retouch skin in post, and it is a matter of personal preference whether you as a photographer choose to retouch skin or go for a more minimal and natural approach to post-processing. This tutorial provides the ‘how to’, so that you have the tools at your disposal to retouch skin as and when needed.

There are many tutorials for this technique using the more popular ‘Photoshop’ software, but it is possible to achieve the same results for free using open-source software such as GIMP. I’m a big fan of GIMP. It’s a bit clunky at times but it’s incredibly powerful and brilliant for beginners who don’t want to shell out for a premium subscription to Photoshop.

I have chosen to use a bare faced self-portrait for this tutorial, not out of a love for seeing my own face at 100% magnification, but rather to spare friends and family the ordeal! The process is a little up close and personal, after all.

1 : Open your image in GIMP.

In order for this tutorial to be effective, I suggest using the largest version of your image that you have at your disposal. I exported my image from Lightroom after post-processing of exposure / tones at 4000px on the long side and then expanded the frame in GIMP (tutorial coming soon). To open an image in GIMP go to ‘File’ and scroll down to ‘Open’.

2: How to zoom.

Zoom in to 100% to see what you will be working on. To do this navigate to ‘View’ – ‘Zoom’ – ‘100%’. In this example, I am working on removing my freckles as a proof of concept.

3 : Duplicating the original image to create separate layers.

The Frequency Separation Method of skin retouching involves separating your image into two layers. One of these layers holds the information concerning colour and exposure – for example skin tones, freckles, heat rash, the skin discolouration of insect bites. The second layers holds the ‘texture’ information. For example hair, pores, dry skin, skin texture. By separating the original image into two layers, it is then possible to work on each of these layers separately. This means that you can change the colour of the skin without removing pores and fine lines and vice versa. As a result, your final image will look much more natural. If you have ever seen a portrait image which looks a bit plastic, it is likely the result of skin retouching which has over smoothed the texture layer, removing details such as pores, fine lines and skin texture.

To begin Frequency Separation, duplicate your original image. To duplicate your original image, right click on it in your layers panel (Ctrl + L will bring up your layers panel if it is missing) and navigate to ‘Duplicate Layer’.

4 : Renaming the ‘low frequency’ layer.

This duplicate layer will be your ‘skin’ layer. Many people call the skin layer the ‘low frequency’ layer, as this is the layer that contains colour detail but no texture detail. Rename your layer to something meaningful to you. I have chosen ‘Skin’. Right click on your duplicate layer (called something like Original.jpg copy), and navigate to ‘Edit Layer Attributes’ where you can insert a new name.

5 : Softening the ‘low frequency’ layer using the Gaussian Blur tool.

Now that we have renamed our low frequency / skin layer, we need to isolate the colour information from the texture information. To do this, we will use the ‘Gaussian Blur’ tool. Please be careful to make sure that you have your skin layer selected in your layers panel (rather than your original layer), and then navigate to ‘Filters’ – ‘Blur’ – ‘Gaussian Blur’.

6 : Gaussian Blur settings. Be careful not to over blur the skin in this step.

Make sure that you have the little key chain connected. This means that the Horizontal and Vertical settings are linked and that if you change one setting the other will change too. Select a blur radius of approximately 8px. You can see a preview in the dialogue panel. You don’t want to over blur the skin at this point, as doing so will reduce the information you have available in your ‘texture’ layer.

7 : Changing the blend mode for the ‘low frequency’ layer.

Now we separate the layers. Select your ‘skin’ layer and navigate in your layers panel to the ‘Mode’ drop down. Select ‘Grain Extract’.

8 : Creating a new layer ‘from visible’.

Right click on your ‘skin layer’ and navigate to ‘New from Visible’. This will create a new layer based upon your skin layer.

9 : Changing the blend mode to create a ‘high frequency’ layer.

Change the mode of this new layer to ‘Grain Merge’ in the same way as you did to your skin layer in Step 7. Now reselect your skin layer, and change the blend mode back to ‘Normal’.

10 : Renaming the ‘high frequency’ layer to something meaningful. You have now separated the skin’s colour tones from the texture and can begin retouching.

Rename your top layer, the layer you created ‘from visible’ to something more meaningful. This is your ‘high frequency’ layer but you may find it more helpful to call it something like ‘Texture’. Follow the instructions in Step 4 to rename your layer.

11 : Using the ellipse select tool to further blend the colour tones of select areas of skin.

If you have followed Step 1 – 10, you should now have separated your original image into two layers. To double check, toggle the little eyes in your layers panel. If you deselect them all you will have a blank canvas. You should find that your ‘skin’ layer is blurred and that your ‘texture’ layer is grey with a very crunchy looking outline of your face, pores, wrinkles, hair etc. The bottom layer is your original image. When combined, your skin and texture layer should look identical to your original image. Now we can begin retouching.

In this tutorial I am retouching the ‘skin’ layer and leaving the ‘texture’ layer untouched. There are several tools I will demonstrate in this tutorial that you can use to retouch skin. Feel free to pick and choose the tools which you feel are most appropriate for the areas of skin you need to work on.

12 : Gaussian Blur settings with the ellipse tool.

The Ellipse Tool Method

Having first made sure that you have selected the ‘skin’ layer in your layers panel, navigate to the Ellipse Select Tool in your tool box (See image 11). This is a good tool to use on the forehead. In ‘Tool Options’ (image 12) make sure that you tick ‘feather edges’ so that you have a soft transition between the blur selection and the rest of your image. You may wish to select a larger blur than you did when creating your ‘skin’ layer in Steps 5 & 6. I opted for a 16px blur but adapt this setting as needed. Again, you can see a preview in the options box.

13 : Using the Free Select Tool.

The Free Select Tool Method

For smaller, irregular areas of the skin it is easier to use the ‘Free Select’ tool than the ‘Ellipse Select’ tool. Again, tick ‘feather edges’ in the Tool Options box. You can select smaller areas of skin this way, and tackle areas such as the nose and under the eyes in small sections.

14 : A quicker way to apply ‘Gaussian Blur’ to your selections.

Rather than going back through the menus each time you need to apply a blur, navigate to ‘Filters’ – ‘Repeat Gaussian Blur’ to quickly repeat your previous blur settings on a new section.

15 : How to use the Clone Tool in GIMP.

The Clone Tool Method

For individual freckles, blemishes or details, it may be better to use the clone or heal tools. The difference between these two tools is the subtlety with which they are applied. The ‘Clone’ tool will take a perfect sample (of colours on the skin layer and texture on the texture layer) from anywhere on your image and apply it to the location you prescribe. The ‘Heal’ tool will take a sample, and ‘repair’ an area, blending the sample you have selected with the existing colour tones of the prescribed area. In order to apply these tools with an even lighter hand, it is possible to select a softer brush or lower the opacity in the ‘Tool Options’ panel as above (image 15).

16 : Sampling skin with the Clone or Heal tools in GIMP

To sample skin, press and hold down ‘Ctrl’ on your keyboard (Windows, or the equivalent key on a Mac) and select an area of skin which is a similar shade to the colour you wish to change your patch of skin to. Once you have selected your sample, you may apply it by clicking on the skin where you wish to apply your sample.

17 : How to use the Heal tool in GIMP.

The Healing Tool Method

The ‘Healing’ tool is applied in exactly the same way as the ‘Clone’ tool, as set out in the previous two steps. Look for the yellow bandages symbol in your toolbox to find the healing tool.

18 : Setting opacity, brush style, brush size etc.

With all of these tools, it is best to work in small patches. You can change the brush shape, size, opacity in Tool Options at any time whilst you are working. If you make a mistake, simply navigate to ‘Edit’ – ‘Undo’.

19 : Skin retouching is now complete.

Freckle free!

20 : A before and after side by side comparison demonstrating freckle removal.

A before and after to demonstrate skin retouching of a lightly freckled face.

 

21 : Flattening the layers.

Once you have finished retouching, you need to flatten your image ready for export. Navigate to ‘Image’ – ‘Flatten Image’.

22 : Exporting the image as a jpeg, tiff or png file.

To export, navigate to ‘File’ and then ‘Export’. Note, if you select ‘Save’ you will save the image as a GIMP file and not a jpeg.


12 Comments

  1. Markus says:

    Thanks for sharing this excellent freq. sep. tutorial for GIMP.

    But: Why removing freckles? You should be happy to be born with 😉

    Cheers
    Markus

    • Stephanie says:

      Thanks, Markus. Glad to hear it was helpful! I’ve nothing against my freckles – I just chose them as an example for the sake of the tutorial! 🙂

  2. Damilola Owoyele says:

    I almost gave up on photography and Gimp because I couldn’t get my pictures to ‘pop’. But reading and practising this post has reinvigorated my passion for photography. Thank you so much.

    • Stephanie says:

      Thanks, Damilola, that’s a really lovely comment to wake up to, and you’ve just hit on the reason I put these tutorials together in the first place! I’m so pleased I could help you with GIMP and that it’s made you excited for photography again. Don’t give up, there are always times when it feels a bit ‘flat’ and nothing quite comes out right, but keep taking photos and you’ll find what works for you and develop your style into something you really love!

  3. Nqobile says:

    All skin retouching tutorials I see are based on the face. Is it the same concept with smoothing out uneven skin tone on say the legs or arms?

    • Stephanie says:

      Yes, exactly the same. Tutorials focus on the face as in portraits they’re the most usual point of focus but the tools and concept can be used for all skin retouching.

  4. Holger Kds says:

    Great tutorial, thank you very much.

  5. Shaleitha Smith-Frazier says:

    This is amazing! Thank you!

  6. Kirsten says:

    Hi! I’ve followed the steps, but when I went to change my “Skin” layer back to Normal, there wasn’t an option for Normal in the mode menu. Also, my photo didn’t turn grey like your example up there. Any ideas? Thanks!

    • Stephanie says:

      Hi Kirsten, I’m sorry to hear you’ve had problems with the tutorial. As I don’t have your example in front of me, all I can suggest is that you try it again from the beginning, just in case you missed a step somewhere along the line. Make sure you have all of your panels open (Tool Options and Layers) which you can toggle on and off at the top under ‘Windows’.