wasabeef/android-gpuimage

GPUImage for Android is a library that lets Android app developers apply visual filters to images using the phone's graphics chip rather than its main processor. Think of it like the filter layer in a photo app: you can make an image look aged and brown (sepia), sharpen it, blur it, detect edges so it looks like a sketch, or combine multiple effects at once. All of that processing happens on the GPU, which is built to handle this kind of work quickly. The project was built to mirror a popular iOS library called GPUImage, and it intentionally reuses the same underlying shader code so developers who know the iOS version can move their filter logic to Android with minimal changes. It requires Android 2.2 or later and works with OpenGL ES 2.0, which is supported on essentially all modern Android devices. To use it, a developer adds a single line to their project's build file, then writes a few lines of code to load an image, attach a filter, and either display it in a preview or save it directly to the device. The library supports both Java and Kotlin, the two main languages used for Android development. The filter library is extensive. It covers color adjustments like brightness, contrast, saturation, hue, and white balance, stylized looks like toon, posterize, sketch, and CGA color, blending modes for layering images, and a range of blur types including Gaussian, box, bilateral, and zoom blur. Many of these come from the iOS original, though not all iOS filters have been ported yet. The README includes a checklist showing which ones are complete and which are still missing. The project is open source under the Apache 2.0 license, which means it can be used freely in both personal and commercial Android apps.