With my recent #30edits challenge, I pushed into new territory, deeply exploring the features and effects in my go-to apps. One of my favorite discoveries is the masking feature in Stackables. Today I’m going to explain how I used this feature to create a recent piece, Gatekeeper.

If you haven’t used the Stackables app before, you can get the basic instructions in this earlier blog post. I’ve also posted many Stackables Formulas in the past, which allow you to use the same layers and settings I used to create an artistic effect. Take a look at those posts for more background. Today we are going to specifically dive in on masking.

Starting with this lovely Oregon winter tree photograph, I’m going to experiment in Stackables.

First, I added a few layers in Stackables, transforming the color and adding texture. When I have a few layers, it’s time to play with masking, by tapping the Mask icon. (Note: I’m sharing iPad screen shots because there is a little more room on the screen to explain the options. All of the features are available on the iPhone as well.)

This opens a whole new menu of options! There are different mask menu options on the top of the screen, masks to choose from the menu on the right, placement options in the lower right corner and extent/opacity selection in the lower left corner.

In this menu, I can choose a mask for the selected layer by tapping on one of the options in the menu on the right. The way the mask works, the black pixels block the selected layer from showing through. You can see that in the image; the green/yellow gradient layer is blocked by the mask. To allow more or less of the layer to show, you use the opacity and extent sliders.

You can also adjust the placement location, angle of rotation and size of the mask by using two fingers on the image and moving the mask around. Alternatively, you can use the preset positioning options in the lower corner. If you are going to mask multiple layers, I recommend you use the presets so all of the masks line up. I’ve opted for the default position in the center.

Now I want to fill that masked area with a contrasting layer/color. I go back to my Layers menu and add another texture layer, then come back to the Mask menu to mask it. I choose the same Mask option, and then invert the mask using the toggle in the upper left corner. This gives me the exact opposite in terms of mask – the new layer shows in that center area, but is masked around the edge. Since I used the preset positioning, the two masks line up perfectly.

An easy way to add another layer with an exactly inverted mask is to duplicate the original masked layer, and then invert the mask. From there, you can go to the Layers menu and choose a new texture/gradient/etc. for the new layer. You can continue to add or duplicate multiple layers with and without masks, but in this case I’m going to save the image from Stackables for the next step in the edit.

The “window” in the sky looks kind of empty, doesn’t it? It needs something. I use Alien Sky to add a moon and subtle stars.

But now I have stars in the outer frame, where I don’t want them. I resolve this by blending the output from Stackables with the output from Alien Sky in Image Blender. I use the mask function in Image Blender to mask the stars in the outer frame, and here you go, the final result:

If you want to learn more about Image Blender masking and the many other functions in that app, it’s covered in-depth in my book, Art with an iPhone: A Photographer’s Guide to Creating Altered Realities.

The last step is, of course, naming the image. Sometimes a name comes to me along the way, and other times I have to explore options. The first name that came to me was “Portal” but that seemed too obvious. I looked at it for a while longer and realized the trees were almost like guardians, and so “Gatekeeper” came along. That was it!

This image is definitely a recent fav and was a direct result of my #30edits exploration. I love learning something new. I hope you do too!