GIMP Adjustment Layers

How to Fake Some Adjustment Layer Effects in GIMP

One of the common complaints about GIMP is that the application doesn't offer Adjustment Layers. As Photoshop users will know, Adjustment Layers are layers that can be used to edit the appearance of all layers stacked below, without actually editing those layers, meaning an Adjustment Layer can be removed at any point and the layers below will appear as before.

Because there are no GIMP Adjustment Layers, layers have to be edited directly and effects cannot be removed later. However, it is possible to fake some basic non-destructive Adjustment Layers effects in GIMP using blending modes.

Don't Expect Miracles

The first thing to say is that this isn't a miracle solution to the GIMP Adjustment Layers issue. It doesn't offer the fine control that you can get using true Adjustment Layers, and most advanced users looking to process their images to produce the finest results will probably consider this a non-starter. However, for less advanced users looking to achieve quick and easy results, these tips may be useful additions to an existing workflow, using the Mode drop down and Opacity slider located in the top of the layers palette.

These tips may not be effective with every image, but in the next few steps I'll show you some quick and easy ways to fake basic GIMP adjustment layers to achieve simple non-destructive editing in GIMP.

Use Screen Mode

If you've got an image that's looking a little dark or under-exposed, such as the one shown in the previous step, a really simple trick to lighten it up is to duplicate the background layer and then change the Mode to Screen.

If you find that the image has gone too bright and some areas have burned out or become pure white, you can reduce the effect by sliding the Opacity slider to the left so that more of the background layer shows through.

Alternatively, if the image still isn't bright enough, you can duplicate the new layer so that now there are two layers set to Screen. Remember, you can fine tune the effect by adjusting the Opacity of this new layer.

Use Layer Masks

I'm happy with the tiled wall in the image in the previous step, but want the t-shirt to be lighter. I can use a Layer Mask so that only the t-shirt is lightened when I duplicate the Screen layer.

I duplicate the Screen layer and then right click on the new layer in the Layers Palette and click Add Layer Mask. I then select Black (full transparency) and click the Add button. With white set as the foreground color, I now paint into the mask with a soft brush so that the t-shirt is unmasked and appears lighter. Alternatively, I could use the Paths Tool to draw around the t-shirt, make a Selection from Path and fill that with white for a similar result. This Vignette tutorial explains Layer Masks in more detail.

Use Soft Light Mode to Lighten

If the t-shirt still isn't light enough following the last step, I could just duplicate the layer and mask again, but another option would be to use the Soft Light Mode and a new layer with a fill of white that matches the mask applied previously.

To do this, I add a new empty layer on top of the existing layers and now right click on the Layer Mask on the layer below and and select Mask to Selection. Now I click on the empty layer and fill the selection with white. After deselecting the selection, I just change the Mode to Soft Light and, if necessary, adjust the Opacity of the layer to fine tune it.

Use Soft Light Mode to Darken

After spending the last few steps lightening the image, this step may seem a bit odd, but it does demonstrate another way to use Soft Light Mode--this time to darken the image. I add another blank layer on top and this time fill the whole layer with black. Now, by changing the Mode to Soft Light, the whole image is darkened. In order to bring some detail back into the t-shirt, I've reduced the Opacity a little.

Experiment, Then Experiment Some More

I said at the beginning that this isn't a true alternative to real GIMP Adjustment Layers, but until a version of GIMP is released with Adjustment Layers, then these little tricks may offer GIMP users some simple options for making non-destructive tweaks to their images.

The best advice I can give is to experiment and see what effects you can produce. Sometimes I apply Soft Light Mode to complete duplicated layers (which I haven't shown here). Do remember that there are many other Modes available that you can also experiment with, such as Multiply and Overlay. If you apply a Mode to a duplicated layer that you don't like, you can easily delete or hide the layer, just as you would if using true Adjustment Layers in GIMP.