# CIFilter An image processor that produces an image by manipulating one or more input images or by generating new image data. ``` class CIFilter ``` ## Overview The `CIFilter` class produces a [`CIImage`](/documentation/CoreImage/CIImage) object as output. Typically, a filter takes one or more images as input. Some filters, however, generate an image based on other types of input parameters. The par`CIFilter` swift.class` object are set and retrieved through the use of key-value pairs. You use the `CIFilter` object in conjunction with other Core Image classes, such as `CIImage`, [`CIContext`](/documentation/CoreImage/CIContext), and [`CIColor`](/documentation/CoreImage/CIColor), to take advantage of the built-in Core Image filters when processing images, creating filter generators, or writing custom filters. `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. To get a quick overview of how to set up and use Core Image filters, see [Core Image Programming Guide](https://developer.apple.com/library/archive/documentation/GraphicsImaging/Conceptual/CoreImaging/ci_intro/ci_intro.html#//apple_ref/doc/uid/TP30001185). ### Create type-safe filters Core Image provides methods that create type-safe `CIFilter` instances. Use these filters to avoid run-time errors that can occur when relying on Core Image’s string-based API. To use the type-safe API, import `CoreImage.CIFilterBuiltins`: ```swift #import #import ``` The type-safe approach returns a non-optional filter. Because the returned filter conforms to the relevant protocol—for example, [`CIFalseColor`](/documentation/CoreImage/CIFalseColor) in the case of [`falseColor()`](/documentation/CoreImage/CIFilter-swift.class/falseColor())—the parameters are available as properties. The following creates and applies a false color filter: ```swift - (CIImage *) falseColorImage:(CIImage*) inputImage { CIFilter *falseColorFilter = CIFilter.falseColorFilter; falseColorFilter.color0 = [CIColor colorWithRed:1 green:1 blue:0]; falseColorFilter.color1 = [CIColor colorWithRed:0 green:0 blue:1]; falseColorFilter.inputImage = inputImage; return falseColorFilter.outputImage; } ``` The false color filter maps luminance to a color ramp of two colors:  ### Subclassing notes You can subclass `CIFilter` in order to create custom filter effects: - By chaining together two or more built-in Core Image filters - By using an image-processing kernel that you write Regardless of whether your subclass provides its effect by chaining filters or implementing its own kernel, you should: - Declare any input parameters as properties whose names are prefixed with `input`, such as `inputImage`. - Override the [`setDefaults()`](/documentation/CoreImage/CIFilter-swift.class/setDefaults()) methods to provide default values for any input parameters you’ve declared. - Implement an `outputImage` method to create a new `CIImage` with your filter’s effect. The `CIFilter` class automatically manages input parameters when archiving, copying, and deallocating filters. For this reason, your subclass must obey the following guidelines to ensure proper behavior: - Store input parameters in instance variables whose names are prefixed with `input`. Don’t use auto-synthesized instance variables, because their names are automatically prefixed with an underscore. Instead, synthesize the property manually. For example: `@synthesize inputMyParameter;` - If using manual reference counting, don’t release input parameter instance variables in your method implementation. The implementation in the `CIFilter` class uses [Key-value coding](https://developer.apple.com/library/archive/documentation/General/Conceptual/DevPedia-CocoaCore/KeyValueCoding.html#//apple_ref/doc/uid/TP40008195-CH25) to automatically set the values of all input parameters to `nil`. ## Topics ### Creating a filter [`+ filterWithName:`](/documentation/CoreImage/CIFilter-swift.class/init(name:)) Creates a [`CIFilter`](/documentation/CoreImage/CIFilter-swift.class) object for a specific kind of filter. [`init(name:withInputParameters:)`](/documentation/CoreImage/CIFilter-swift.class/init(name:withInputParameters:)) Creates a [`CIFilter`](/documentation/CoreImage/CIFilter-swift.class) object for a specific kind of filter and initializes the input values. [`+ filterWithName:keysAndValues:`](/documentation/CoreImage/CIFilter-swift.class/filterWithName:keysAndValues:) Creates a [`CIFilter`](/documentation/CoreImage/CIFilter-swift.class) object for a specific kind of filter and initializes the input values with a `nil`-terminated list of arguments. ### Configuring type-safe filters Configure Core Image filters that expose their attributes as properties. [`CIFilterProtocol`](/documentation/CoreImage/CIFilterProtocol) The properties you use to configure a Core Image filter. [Blur Filters](/documentation/CoreImage/blur-filters) Apply blurs, simulate motion and zoom effects, reduce noise, and erode and dilate image regions. [Color Adjustment Filters](/documentation/CoreImage/color-adjustment-filters) Apply color transformations, including exposure, hue, and tint adjustments. [Color Effect Filters](/documentation/CoreImage/color-effect-filters) Apply color effects, including photo effects, dithering, and color maps. [Composite Operations](/documentation/CoreImage/composite-operations) Composite images by using a range of blend modes and compositing operators. [Convolution Filters](/documentation/CoreImage/convolution-filters) Produce effects such as blurring, sharpening, edge detection, translation, and embossing. [Distortion Filters](/documentation/CoreImage/distortion-filters) Apply distortion to images. [Generator Filters](/documentation/CoreImage/generator-filters) Generate barcode, geometric, and special-effect images. [Geometry Adjustment Filters](/documentation/CoreImage/geometry-adjustment-filters) Translate, scale, and rotate images in 2D and 3D. [Gradient Filters](/documentation/CoreImage/gradient-filters) Generate linear and radial gradients. [Halftone Effect Filters](/documentation/CoreImage/halftone-effect-filters) Simulate monochrome and CMYK halftone screens. [Reduction Filters](/documentation/CoreImage/reduction-filters) Create statistical information about an image. [Sharpening Filters](/documentation/CoreImage/sharpening-filters) Apply sharpening to images. [Stylizing Filters](/documentation/CoreImage/stylizing-filters) Create stylized versions of images by applying effects including pixelation and line overlays. [Tile Effect Filters](/documentation/CoreImage/tile-effect-filters) Produce tiled images from source images. [Transition Filters](/documentation/CoreImage/transition-filters) Transition between two images by using effects including page curl and swipe. ### Accessing registered filters [`+ filterNamesInCategories:`](/documentation/CoreImage/CIFilter-swift.class/filterNames(inCategories:)) Returns an array of all published filter names that match all the specified categories. [`+ filterNamesInCategory:`](/documentation/CoreImage/CIFilter-swift.class/filterNames(inCategory:)) Returns an array of all published filter names in the specified category. ### Registering a filter [`+ registerFilterName:constructor:classAttributes:`](/documentation/CoreImage/CIFilter-swift.class/registerName(_:constructor:classAttributes:)) Publishes a custom filter that is not packaged as an image unit. ### Getting filter parameters and attributes [`name`](/documentation/CoreImage/CIFilter-swift.class/name) A name associated with a filter. [`enabled`](/documentation/CoreImage/CIFilter-swift.class/isEnabled) A Boolean value that determines whether the filter is enabled. Animatable. [`attributes`](/documentation/CoreImage/CIFilter-swift.class/attributes) A dictionary of key-value pairs that describe the filter. [`inputKeys`](/documentation/CoreImage/CIFilter-swift.class/inputKeys) The names of all input parameters to the filter. [`outputKeys`](/documentation/CoreImage/CIFilter-swift.class/outputKeys) The names of all output parameters from the filter. [`outputImage`](/documentation/CoreImage/CIFilter-swift.class/outputImage) Returns a [`CIImage`](/documentation/CoreImage/CIImage) object that encapsulates the operations configured in the filter. ### Setting default values [`- setDefaults`](/documentation/CoreImage/CIFilter-swift.class/setDefaults()) Sets all input values for a filter to default values. ### Applying a filter [`- apply:arguments:options:`](/documentation/CoreImage/CIFilter-swift.class/apply(_:arguments:options:)) Produces a [`CIImage`](/documentation/CoreImage/CIImage) object by applying arguments to a kernel function and using options to control how the kernel function is evaluated. [`- apply:`](/documentation/CoreImage/CIFilter-swift.class/apply:) Produces a [`CIImage`](/documentation/CoreImage/CIImage) object by applying a kernel function. ### Getting localized information for registered filters [`+ localizedNameForFilterName:`](/documentation/CoreImage/CIFilter-swift.class/localizedName(forFilterName:)) Returns the localized name for the specified filter name. [`+ localizedNameForCategory:`](/documentation/CoreImage/CIFilter-swift.class/localizedName(forCategory:)) Returns the localized name for the specified filter category. [`+ localizedDescriptionForFilterName:`](/documentation/CoreImage/CIFilter-swift.class/localizedDescription(forFilterName:)) Returns the localized description of a filter for display in the user interface. [`+ localizedReferenceDocumentationForFilterName:`](/documentation/CoreImage/CIFilter-swift.class/localizedReferenceDocumentation(forFilterName:)) Returns the location of the localized reference documentation that describes the filter. ### Creating a configuration view for a filter [`- viewForUIConfiguration:excludedKeys:`](/documentation/CoreImage/CIFilter-swift.class/view(forUIConfiguration:excludedKeys:)) Returns a filter view for the filter. ### Applying system tone mapping modes [`CIDynamicRangeOption`](/documentation/CoreImage/CIDynamicRangeOption) An enum string type that your code can use to select different System Tone Mapping modes. ### Constants [Filter Attribute Keys](/documentation/CoreImage/filter-attribute-keys) Attributes for a filter and its parameters. [Data Type Attributes](/documentation/CoreImage/data-type-attributes) Numeric data types. [Vector Quantity Attributes](/documentation/CoreImage/vector-quantity-attributes) Vector data types. [Color Attribute Keys](/documentation/CoreImage/color-attribute-keys) Color types. [Image Attribute Keys](/documentation/CoreImage/image-attribute-keys) Image Types [Filter Category Keys](/documentation/CoreImage/filter-category-keys) Categories of filters. [Options for Applying a Filter](/documentation/CoreImage/options-for-applying-a-filter) Options that control the application of a custom Core Image filter. [User Interface Control Options](/documentation/CoreImage/user-interface-control-options) Sets of controls for various user scenarios. [User Interface Options](/documentation/CoreImage/user-interface-options) Keys or values for the size of the input parameter controls for a filter view. [Filter Parameter Keys](/documentation/CoreImage/filter-parameter-keys) Keys for input parameters to filters. [RAW Image Options](/documentation/CoreImage/raw-image-options) Options for creating a [`CIFilter`](/documentation/CoreImage/CIFilter-swift.class) object from RAW image data. ### Deprecated [`init(CVPixelBuffer:properties:options:)`](/documentation/CoreImage/CIFilter-swift.class/init(CVPixelBuffer:properties:options:)-7qpsv) Creates a filter from a Core Video pixel buffer. [`+ filterWithImageData:options:`](/documentation/CoreImage/CIFilter-swift.class/init(imageData:options:)) Creates a filter that allows the processing of RAW images. [`+ filterWithImageURL:options:`](/documentation/CoreImage/CIFilter-swift.class/init(imageURL:options:)) Creates a filter that allows the processing of RAW images. [`CIRAWFilterOption`](/documentation/CoreImage/CIRAWFilterOption) [`+ serializedXMPFromFilters:inputImageExtent:`](/documentation/CoreImage/CIFilter-swift.class/serializedXMP(from:inputImageExtent:)) Serializes filter parameters into XMP form that is suitable for embedding in an image. [`+ filterArrayFromSerializedXMP:inputImageExtent:error:`](/documentation/CoreImage/CIFilter-swift.class/filterArray(fromSerializedXMP:inputImageExtent:error:)) Returns an array of filter objects de-serialized from XMP data. [`+ supportedRawCameraModels`](/documentation/CoreImage/CIFilter-swift.class/supportedRawCameraModels()) ### Type methods [`+ areaAlphaWeightedHistogramFilter`](/documentation/CoreImage/CIFilter-swift.class/areaAlphaWeightedHistogram()) [`+ areaBoundsRedFilter`](/documentation/CoreImage/CIFilter-swift.class/areaBoundsRed()) [`+ maximumScaleTransformFilter`](/documentation/CoreImage/CIFilter-swift.class/maximumScaleTransform()) [`+ toneMapHeadroomFilter`](/documentation/CoreImage/CIFilter-swift.class/toneMapHeadroom()) ## Relationships ### Conforms To [`NSSecureCoding`](/documentation/Foundation/NSSecureCoding) [`Equatable`](/documentation/Swift/Equatable) [`CustomDebugStringConvertible`](/documentation/Swift/CustomDebugStringConvertible) [`CVarArg`](/documentation/Swift/CVarArg) [`Hashable`](/documentation/Swift/Hashable) [`NSCoding`](/documentation/Foundation/NSCoding) [`CustomStringConvertible`](/documentation/Swift/CustomStringConvertible) [`NSCopying`](/documentation/Foundation/NSCopying) [`NSObjectProtocol`](/documentation/ObjectiveC/NSObjectProtocol) ### Inherited By [`CIRAWFilter`](/documentation/CoreImage/CIRAWFilter) ### Inherits From [`NSObject-swift.class`](/documentation/ObjectiveC/NSObject-swift.class) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)