Before I began with digital photography, I painted and would incorporate various materials into my pieces to create textured looks. Now I'm replacing my pumice, garnet, and mica gels with photos of sand, gravel, bark, etc. to texture my images.
To begin, I have an image that I've already done my basic retouching to fix skin issues and inconsistencies with the background (frequency separation, dodge/burn, cloning/heal).
Like the previous tutorial, I'm going to duplicate the background layer by right clicking on it. Another trick with Gimp, there is a duplicate layer icon at the bottom of the layers box (see 2nd picture). Alternatively, you can also go to the Layers menu at the top of the screen and select duplicate layer from there (for any editing program).
Going forward, these are suggestions, but feel free to experiment with your work. I'm showing my typical thought process when creating art, but others have different approaches. After I duplicate my background layer, I will open another layer with my texture image. There are numerous sites where you can download creative commons images for texturing or you can simply take some of your own shots. I have an entire folder devoted to textures with macro shots of various things such as dirt, grass, rocks, cement, wood, etc. If you're in need of texture images, I have a second Flickr account devoted to creative commons images where you can download some for texturing: https://www.flickr.com/photos/jeannienadjastudioscc/
You can also find creative commons texture images at Texturemate.com or by searching through Flickr's creative commons photos. Be sure to check that the licensing is set to derivatives allowed and if you plan on using the images commercially, the licensing must be set to include commercial work as some of it is only for personal works. For questions regarding how Creative Commons licensing works, this is a wonderful resource: https://creativecommons.org/licenses/
So here is my texture shot SOOC (straight off of camera). This is a close up of a ceramic planter on my front porch. I will open it by simply dragging and dropping it into my open Gimp file. However, you can also open it by going to the File menu and selecting "Open as Layers" then selecting the file you wish to open.
If the texture image is larger than your background image, you will notice a dashed yellow line around the image to show how big it is. If it's smaller, you'll see your background image peaking out underneath. Either way, you will need to resize your texture layer. To do this, select the Scale tool and click on the texture image.
Before we begin clicking and dragging in the corners to resize the image, please note that the dialogue box will always open with the width and height being unlocked. If you wish for your resizing to be scaled proportionately, click the lock icon to lock the width and height.
Once you have the image resized, click the scale button to scale complete the process. You don't necessarily need to scale the texture image to the exact size of your background image. You can leave excess over the edges. To remove the excess, simply go to your Layer menu and click "Layer to Image Size".
So now I have my texture layer which defaults to "normal" mode and covers my background layer entirely. This is where I can play with modes and masks to manipulate the color and only show some of the texture. Below is the image with each of the layer modes selected and the opacity set at 100% to give you an idea of what is possible.
(Left to Right: Darken Only, Multiply, Burn, Overlay, Soft Light, Hard Light)
(Left to Right: Difference, Subtract, Grain Extract, Grain Merge, Divide, Hue)
(Left to Right: Saturation, Color, Value)
For my image, I'm going to use Grain Merge and reduce the opacity of my texture layer to 35%.
Now I don't want her whole face to have texture on it. This is where I will add a layer mask to my texture layer. In this case, I want a white layer mask so that I can still see the texturing and I will paint with a black brush to remove what I don't like.
I like to mask back in the original parts of the face, keeping the eyes as clear as possible. Below is my layer mask showing.
If you find some spots are not easily removed or still look awkward, you can select the texture layer itself and use the heal tool to remove "rough" patches. You can also apply various blur filters to either the texture layer itself or the mask to create different effects.
Since I have my background layer duplicated, I can use the duplicate (showing as the middle layer) and change the color of it with curves to enhance effects.
(Left to Right: Middle layer Original colors, Curves applied, Desaturation)
You can add as many texture layers as you'd like and remove as much as you wish with layer masks. Again, you can also change the opacity and modes to achieve different effects. Feel free to experiment and enjoy that this is entirely digital so no need to worry about wasting paints or water!
Below is the final image that I created from applying these techniques. Please feel free to share your creations, ask questions, or give any suggestions in the comments section. I hope this tutorial has been helpful and happy editing :)
Special thanks to my lovely model, Jacquelynn Schlegel!