Compositor

If you are looking to ditch Adobe's subscription model but find GIMP's interface too jarring for your daily workflow, Compositor is worth a serious look. Built specifically as a native Mac image editor, it recreates the core compositing and post-processing tools familiar to Photoshop users without the bloated licensing fees or awkward cross-platform UI paradigms. Because it is completely open source, you can clone the native Xcode project and modify the toolset directly to match your custom production requirements. ### Installation You can download compiled binaries directly from the project's GitHub Releases or install the cask via Homebrew: ```sh brew install --cask robbietilton-compositor ``` ### Architecture & Engine Capabilities Compositor focuses heavily on maintaining a non-destructive pipeline while keeping GPU utilization high for smooth canvas interactions. * GPU-Accelerated Layer Effects: Rendering for key layer effects—including Stroke, Drop Shadow, Inner Shadow, Color Overlay, Outer Glow, and Inner Glow—is offloaded directly to the GPU. These effects remain live and editable at any stage without forcing you to rasterize your adjustments. * Non-Destructive Transform Engine: Scale operations do not discard underlying pixel data. The transformation system preserves original image resolution regardless of how small you scale a layer down. It supports snapping to canvas/layer edges or centers, axis locking via `Shift`, and free distortion using `⌘-drag`. * Deep Layer & Mask Hierarchy: Folder hierarchies correctly pass down opacity adjustments to child layers, maintaining Photoshop's blend mode ordering. Masking mechanics operate beyond a layer's physical pixel boundaries, letting you paint, fill, invert, blur, or feather anywhere on the canvas. Masks can also be unlinked to transform separately from their base layer. * Adjustment Layers & Filters: Native non-destructive adjustment layers include Curves, Levels, Exposure, Hue/Saturation, Gradient Map, Grain, Color Balance, Black & White, Invert, Gaussian Blur, Motion Blur, and Noise. * Selections and Content-Aware Processing: The selection suite covers Marquee, Lasso, Wand, and Object selection (switched via `Tab`), along with automated `Select Subject` functionality. Retouching features rely on a content-aware engine that powers both the Spot Healing Brush and Content-Aware Fill, which can extend pixels beyond the canvas border. ### Developer & Workflow Takeaway Compositor nails the execution by mirroring essential keybindings—like `B` and `E` for brush/eraser toggles, `⌘E` for layer merging, and `⌘C`/`⌘V` for transferring whole layer trees between separate projects. For Swift and macOS developers, having access to an open Xcode codebase that handles high-performance layer compositing, GPU shader effects, and canvas transformations makes Compositor an outstanding reference project as well as a practical daily driver.