An evaluation context for rendering image processing results and performing image analysis.
SDKs
- iOS 5.0+
- macOS 10.4+
- tvOS 9.0+
- Mac Catalyst 13.0+Beta
Framework
- Core Image
Declaration
class CIContext : NSObject
Overview
The CIContext class provides an evaluation context for Core Image processing with Quartz 2D, Metal, or OpenGL. You use CIContext objects in conjunction with other Core Image classes, such as CIFilter, CIImage, and CIColor, to process images using Core Image filters. You also use a Core Image context with the CIDetector class to analyze images—for example, to detect faces or barcodes.
CIContext and CIImage objects are immutable, so multiple threads can use the same CIContext object to render CIImage objects. However, CIFilter objects are mutable and thus cannot be shared safely among threads. Each thread must create its own CIFilter objects, but you can pass a filter’s immutable input and output CIImage objects between threads.