Loopix is a professional iOS camera app built around authentic analog film emulation. It combines a real-time GPU-accelerated filter pipeline with physically-based film grain to produce images that look and feel like actual film stock.
Color and B&W presets inspired by classic film stocks — Kodak Portra, Fujifilm Velvia, cinematic stocks, and more. Each preset has its own tone curve, color grade, and grain signature.
Grain is rendered on the GPU via a custom Metal shader that models silver halide crystal development. Three noise layers (Gaussian, Simplex 2D, Worley) combine to produce realistic grain texture. Parameters per preset:
- Amount — grain density with a film-like response curve
- Size — crystal scale (0.5×–4.0× pixel radius)
- Roughness — texture coarseness
- Clumping — simulates grain clustering in dense areas
- Monochromatic — desaturated grain vs. color noise
Grain animation rate adapts via accelerometer — it slows when the camera is stationary so the image stays readable.
Each filter can be blended from 0% (original) to 100% (full effect) in real time using an on-screen dial. Intensity is saved per filter across sessions.
Automatically enumerates all available lenses (ultra-wide, wide, telephoto) and lets you switch between them mid-session.
- EV compensation: −3.0 to +3.0 stops via a circular wheel
- Focus point: tap anywhere on the frame
- AE/AF lock: lock focus and exposure independently
- Grid overlay: rule-of-thirds guide
- Photo: full-resolution HEIC output in P3 color space, filters applied post-capture
- Video: live filter preview during recording, filter switching while recording
Onboarding asks for handedness. The shutter button repositions for left- or right-handed grip. Can be toggled any time from the main view.
| Layer | Technology |
|---|---|
| UI | SwiftUI, @Observable |
| Camera | AVFoundation |
| Live preview | Metal / MetalKit (MTKView) |
| Filter pipeline | CoreImage |
| Grain rendering | Metal compute shaders |
| Motion | CoreMotion |
| Purchases | StoreKit 2 |
| Photos | PHPhotoLibrary |
No third-party dependencies. Pure Swift + Apple frameworks.
AVCaptureSession
└── AVCaptureVideoDataOutput → MetalPreviewRenderer → MTKView (30fps live preview)
└── AVCapturePhotoOutput → PhotoCaptureProcessor → CoreImage pipeline → HEIC → Photos
Live preview: each frame goes through MetalPreviewRenderer, which applies the full filter pipeline via CoreImage and composites real-time grain on top using a Metal shader.
Photo capture: PhotoCaptureProcessor receives the raw pixel buffer, runs the same CoreImage pipeline at full resolution, adds grain, and saves HEIC at ~0.9 quality to the photo library.
Each frame runs through a chained CIFilter graph:
Exposure adjustment
→ Temperature & tint
→ Saturation
→ Per-channel tone curves (R, G, B, Alpha — 5-point cubic spline)
→ Split toning (shadow hue + highlight hue)
→ Fade (black lift)
→ Film clamp
→ Vignette
→ CIDissolveTransition (intensity blend with original)
Tone curves are encoded as 5 control points (shadows, darks, midtones, lights, highlights), solved as a constrained cubic polynomial, and evaluated on the GPU via CIColorPolynomial.
GrainKernel.metal runs as a compute kernel over every output pixel. It mixes:
- Gaussian noise — fine-grain base texture
- Simplex 2D noise — large-scale tonal variation
- Worley noise — crystal clumping effect
Grain operates in the optical density domain (logarithmic), matching the physics of silver halide development. A frame-count–based time coordinate prevents floating-point precision loss on long sessions.
CameraState(@Observable) — filter selection, grain settings, EV, lens index, capture modeCameraManager— owns and drivesAVCaptureSessionon a dedicated serial queueCaptureDeviceManager— enumerates lenses sorted by focal lengthSubscriptionManager— StoreKit 2 transaction listener, persistsisProto UserDefaults- Per-filter intensity map persisted in UserDefaults
- iOS 17.0+
- Swift 6.0
- Xcode 16+
- Physical device required (camera not available in Simulator)
- Clone the repo
- Open
Camera.xcodeprojin Xcode - Select your development team in Signing & Capabilities
- Run on a physical iPhone
No additional setup needed — no SPM packages, no CocoaPods.
The app uses a freemium model. Free users have access to 3 presets (clean, mono, portra). A Pro subscription unlocks all 28 presets and removes the watermark overlay on locked filters.
Subscription products are configured in Products.storekit. For local testing, use Xcode's StoreKit sandbox.
This project is licensed under the PolyForm Noncommercial License 1.0.0 — see LICENSE for full terms.
In short: you are free to view, fork, and modify the code for noncommercial purposes. Commercial use is not permitted without explicit written permission from the author.
© 2024 Tronin Denis