Apple image representation workflow

Apple Image Representation Workflow

Purpose

Guide image source, destination, representation, and conversion work without flattening distinct Apple image types into a generic wrapper. Keep file encoding, rendered pixels, processing recipes, platform display containers, metadata, and auxiliary images visibly separate.

When To Use

• Use for Image I/O sources and destinations, metadata, thumbnails, incremental loading, multi-frame images, CGImage, NSImage, NSImageRep, NSBitmapImageRep, UIImage, and representation conversion.
• Recommend core-image-processing-workflow when filters, compositing, RAW development, custom kernels, or rendering are primary.
• Recommend the Vision workflow when the requested outcome is recognition or analysis rather than representation ownership.

Single-Path Workflow

1. Classify the request:
   • source inspection or decoding
   • incremental loading or thumbnailing
   • metadata or auxiliary data
   • destination encoding or multi-frame output
   • Core Graphics raster ownership
   • AppKit representation or drawing
   • UIKit image display ownership
   • conversion or repair
2. Apply the Apple docs gate:
   • read current Image I/O, Core Graphics, AppKit, or UIKit documentation first
   • state the documented behavior relied on
   • check API, image-format, auxiliary-data, and platform availability before promising a decode, encode, or representation path
   • apply ../../shared/references/apple-image-type-ownership.md
   • use references/image-io-decoding-encoding-and-metadata.md for source and destination work
   • use references/apple-image-representations-and-bridging.md for type selection and conversion
3. Preserve source meaning:
   • inspect type, frame count, dimensions, properties, orientation, color profile, alpha, dynamic range, and auxiliary data before conversion
   • choose decode-time thumbnailing or incremental loading when the workload requires it
   • identify whether metadata and original encoded bytes must survive
4. Choose the representation:
   • CGImage for concrete raster pixels and Core Graphics drawing
   • CIImage for a lazy processing graph
   • NSImage and NSImageRep for macOS display-oriented multi-representation behavior
   • UIImage for UIKit display semantics including scale and orientation
   • CVPixelBuffer for frame-oriented media and hardware interop
5. Encode deliberately:
   • choose destination type, frame count, properties, metadata policy, orientation policy, color profile, compression, and auxiliary-data policy
   • add every image or frame
   • require successful CGImageDestinationFinalize before claiming output exists
6. Return one recommendation with source facts, chosen types, conversion losses, decode/encode plan, memory and cancellation policy, diagnostics, and validation.

Inputs

• request: image representation, decode, encode, metadata, or conversion task.
• representation_goal: inspect, decode, thumbnail, incremental, metadata, encode, appkit, uikit, bridge, or repair.
• platform_context: ios, ipados, macos, tvos, watchos, visionos, or mixed-apple.

Outputs

• status: success, handoff, or blocked.
• path_type: primary when image representation owns the work, fallback when processing, analysis, capture, or codecs own it.
• output: documented behavior, source inventory, selected representation, conversion-loss ledger, decode/encode plan, diagnostics, and validation.

Guards and Stop Conditions

• Do not assume NSImage contains one fixed bitmap; it can own multiple representations and select among them for drawing.
• Do not assume UIImage, NSImage, CGImage, and CIImage preserve the same orientation, scale, metadata, color, or rendering semantics.
• Do not fully decode large images merely to produce a small thumbnail when Image I/O thumbnailing fits the requirement.
• Do not discard source metadata, ICC profiles, animation frames, depth, disparity, gain maps, mattes, or other auxiliary data silently.
• Do not claim an encoded destination succeeded before finalization returns success.
• Do not invent image repositories, managers, or mirrored metadata models when Image I/O properties and framework values express the boundary.
• Stop when required source bytes, format support, destination policy, or preservation requirements are unavailable.

Fallbacks and Handoffs

• Recommend core-image-processing-workflow for filters, RAW development, compositing, color processing, custom kernels, or rendering.
• Recommend vision-image-analysis-workflow for recognition and analysis.
• Recommend appkit-app-architecture-workflow for broader macOS view, controller, window, or application ownership.
• Recommend avfoundation-media-pipeline-workflow for assets, capture, video, readers, writers, or export.
• Recommend photos-library-editing-workflow for PhotoKit and PhotosUI ownership.
• Recommend xcode-build-run-workflow for target resources, build, run, device, or profiling follow-through.
• Recommend xcode-testing-workflow for image fixtures, metadata round trips, comparison tests, or performance baselines.
• Recommend explore-apple-swift-docs when documentation lookup is the real need.

Customization

Use references/customization-flow.md. This workflow defines no runtime-enforced knobs.

References

• references/image-io-decoding-encoding-and-metadata.md
• references/apple-image-representations-and-bridging.md
• references/customization-flow.md
• ../../shared/references/apple-image-type-ownership.md
• Recommend references/snippets/apple-xcode-project-core.md for reusable Xcode-project policy.

Script Inventory

• scripts/customization_config.py