a tutorial on slightly advanced amoled wallpaper editing

june 1, 2021

For those not in the loop, many flagship phones and some high-end desktop monitors have these things called “AMOLED” displays, that let them actually turn off individual pixels completely. If your home screen (for instance) is mostly true black—exactly #000000—then those pixels will be actually turned off and save a not-insignificant amount of energy, and can significantly extend battery life since the display is usually the biggest battery killer. As such, I try to set all my apps (not that I use many) to the darkest theme they have, and only use ≥70% true black wallpapers.

If you want to look for existing AMOLED backgrounds, there’s a good subreddit for it: r/Amoledbackgrounds

The above subreddit has a pretty good tutorial on editing your own AMOLED background:

AMOLED in 30 Seconds

But unfortunately it’s only helpful for a very small number of images that can be adequately edited solely using curves and color adjustment. I wrote this tutorial for a “step up” from that: it still needs a specific type of image, but it doesn’t need to be a /perfect/ image, as long as you can mask out the light parts then you’re golden.

[1.0mib] The before and after of what we’re making

Source image used throughout this post, used with permission.

Fair warning, I wrote this post around eight months ago when I first posted the final edited wallpaperᵃ and I forgot to post it until now.

[a]: the final wallpaper if that’s all you want

step 1: choosing your source image and importing

[1.7mib] The raw starting image, cropped to the resolution you want (in this case, 1800x2400)

Generally, your image should roughly follow the requirements in "AMOLED in 30 Seconds", but there can be areas of the background that are bright and not suitable for that tutorial. The main thing is that the majority of the background should be darker than the foreground. For this source image, the background in the top 75% is fine, but the white perch means it doesn’t work well just adjusting the curves.

Once you’ve chosen your image drag-’n’-drop it into GIMP and crop it to the size you want.

step 2: early mask

[1.0mib] Don’t make the outline too close to the subject, we’ll be going back and making the “real” outline later on

Create a layer mask (Right click on the layer, click on Add Layer Mask) and give the subject a *very* rough outline with a large brush. Make sure you have the layer mask and not the layer itself selected, and make sure your brush color is 100% black. I primarily do this so I don’t get distracted by the background when adjusting the curves, and to save me some work filling in the rest of the mask later.

step 3: edit the curves

Click back to the image from the layer mask, then to to Colors→Curves. You probably want to move the shadows point (the bottom left dot) to the right, and the highlights point (the top right dot) down. You can add some nodes in the middle, and just play around with it until it looks good. This part of the edit is basically the AMOLED in 30 Seconds tutorial, so you can go follow that.

[70.0kib] an example of what the curves could look like

[1.4mib] Before and after curves adjustment

step 4: rough outline

Use a relatively large Hardness 75 brush, and outline all the way around the subject. When outlining, keep the edge of the circle right on the edge of the subject, like is shown in the following picture. This is still a rough outline, so don’t worry about areas of detail or tight corners yet. What you’re hoping for is that most of the outline is adequately masked with this, so all you’ll have to focus on is those areas of detail.

[64.0kib] A sample brush configuration for this part

[519.4kib] An example of how you should hold the brush when outlining this part

step 5: detailed outline

step 5.1: the outline itself

This takes a lot of work to do, so only do it on detailed areas of the subject that show background through them, like tufts of fur or feathers. If you can, skip it. You want a 100 Hardness brush at size 1.

[62.0kib] A sample brush configuration for this part

Start outlining the area that you’re detailing, don’t worry about filling in anything yet.

[327.9kib] Starting the outline

[456.7kib] The full outline I did (it extends up into the black part near the top too)

step 5.2: filling in the outline

Right click on the layer mask in the sidebar and select "Show Layer Mask." This should show the mask itself, like below.

[275.2kib] the detailed mask outline

Leaving your Hardness 100 brush, make it a little bigger and start filling in the outline you made before

[274.9kib] Starting to fill in the outline

[271.5kib] Continuing to fill in…

[274.2kib] The fully filled-in mask

step 6: checking the mask and exporting

Right-clicking on the mask again and unchecking "Show Layer mask" and… it doesn’t look great. There’s usually going to be some spots that don’t work out. Sometimes you can take a 50% or 25% opacity brush and try to soften the edges of your mask, but sometimes, like I did here, you just have to mask it out. I decided to mask out the talon completely.

[456.7kib] the bad-looking talon mask

[49.7kib] The final mask used after I painted over the leg and talon. Notice how the edge is pretty fuzzy other than a few areas of detail.

Now you can export your image (as a PNG, JPG will ruin the true black areas). A reminder to check your image on your real AMOLED screen or a TrueColor monitor before posting it anywhere. In this image, there were a few spots of detail that had a dark background behind them that I tried to cheat on, but after looking at it on my phone it looked bright green behind it, so I had to go back and mask it out.

[603.3kib] The final result!

And there! You should now have a beautiful, battery-saving wallpaper for whatever device you want to use it on!