CIFilter Class Reference

Inherits from
Conforms to
Framework
Library/Frameworks/CoreImage.framework
Availability
Available in OS X v10.4 and later.
Declared in
CIFilter.h
CIRAWFilter.h
Companion guides
Related sample code

Overview

The CIFilter class produces a 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 parameters of a CIFilter 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, and CIColor, to take advantage of the built-in Core Image filters when processing images, creating filter generators, or writing custom filters.

CIFilter objects, are not mutable. A CIFilter object cannot be shared safely among threads. If you app is multithreaded, each thread must create its own CIFilter object. Otherwise, your app could behave unexpectedly.

To get a quick overview of how to set up and use Core Image filters, see Core Image Programming Guide.

Subclassing Notes

You can subclass CIFilter in order to create custom filter effects:

See Core Image Programming Guide for details.

Methods to Override

Regardless of whether your subclass provides its effect by chaining filters or implementing its own kernel, you should:

Special Considerations

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:

Tasks

Creating a Filter

Creating a Filter from a RAW Image

Accessing Registered Filters

Registering a Filter

Getting Filter Parameters and Attributes

Setting Default Values

Applying a Filter

Getting Localized Information for Registered Filters

Serializing and Deserializing Filters

Class Methods

filterArrayFromSerializedXMP:inputImageExtent:error:

Returns an array of filter objects de-serialized from XMP data.

+ (NSArray*)filterArrayFromSerializedXMP:(NSData *)xmpData inputImageExtent:(CGRect)extent error:(NSError **)outError
Parameters
xmpData

The XMP data created previously by calling serializedXMPFromFilters:inputImageExtent:.

extent

The extent of the image from which the XMP data was extracted.

outError

The address of an NSError object for receiving errors, otherwise nil.

Availability
  • Available in OS X v10.9 and later.
Declared In
CIFilter.h

filterNamesInCategories:

Returns an array of all published filter names that match all the specified categories.

+ (NSArray *)filterNamesInCategories:(NSArray *)categories
Parameters
categories

One or more of the filter category keys defined in “Filter Category Keys.” Pass nil to get all filters in all categories.

Return Value

An array that contains all published filter names that match all the categories specified by the categories argument.

Discussion

When you pass more than one filter category, this method returns the intersection of the filters in the categories. For example, if you pass the categories kCICategoryBuiltIn and kCICategoryColorAdjustment, you obtain all the filters that are members of both the built-in and color adjustment categories. But if you pass in kCICategoryGenerator and kCICategoryStylize, you will not get any filters returned to you because there are no filters that are members of both the generator and stylize categories. If you want to obtain all stylize and generator filters, you must call the filterNamesInCategories: method for each category separately and then merge the results.

Availability
  • Available in OS X v10.4 and later.
Declared In
CIFilter.h

filterNamesInCategory:

Returns an array of all published filter names in the specified category.

+ (NSArray *)filterNamesInCategory:(NSString *)category
Parameters
category

A string object that specifies one of the filter categories defined in “Filter Category Keys.”

Return Value

An array that contains all published names of the filter in a category.

Availability
  • Available in OS X v10.4 and later.
Declared In
CIFilter.h

filterWithImageData:options:

Returns a CIFilter object initialized with RAW image data supplied to the method.

+ (CIFilter *)filterWithImageData:(NSData *)data options:(NSDictionary *)options;
Parameters
data

The RAW image data to initialize the object with.

options

A options dictionary. You can pass any of the keys defined in “RAW Image Options” along with the appropriate value. You should provide a source type identifier hint key (kCGImageSourceTypeIdentifierHint) and the appropriate source type value to help the decoder determine the file type. Otherwise it’s possible to obtain incorrect results. See the Discussion for an example

Return Value

A CIFilter object.

Discussion

After calling this method, the CIFilter object returns a CIImage object that is properly processed similar to images retrieved using the outputImage key.

Availability
  • Available in OS X v10.5 and later.
Declared In
CIRAWFilter.h

filterWithImageURL:options:

Returns a CIFilter object initialized with data from a RAW image file.

+ (CIFilter *)filterWithImageURL:(NSURL *)url options:(NSDictionary *)options;
Parameters
url

The location of a RAW image file.

options

An options dictionary. You can pass any of the keys defined in “RAW Image Options”.

Return Value

A CIFilter object.

Discussion

After calling this method, the CIFilter object returns a CIImage object that is properly processed similar to images retrieved using the outputImage key.

Availability
  • Available in OS X v10.5 and later.
Declared In
CIRAWFilter.h

filterWithName:

Creates a CIFilter object for a specific kind of filter.

+ (CIFilter *)filterWithName:(NSString *)name
Parameters
name

The name of the filter. You must make sure the name is spelled correctly, otherwise your app will run but not produce any output images. For that reason, you should check for the existence of the filter after calling this method.

Return Value

A CIFilter object whose input values are undefined.

Discussion

You should call setDefaults after you call this method or set values individually by calling setValue:forKey.

Availability
  • Available in OS X v10.4 and later.
Declared In
CIFilter.h

filterWithName:keysAndValues:

Creates a CIFilter object for a specific kind of filter and initializes the input values.

+ (CIFilter *)filterWithName:(NSString *)name keysAndValues:key0, ...
Parameters
name

The name of the filter. You must make sure the name is spelled correctly, otherwise your app will run but not produce any output images. For that reason, you should check for the existence of the filter after calling this method.

key0,

A list of key-value pairs to set as input values to the filter. Each key is a constant that specifies the name of the input value to set, and must be followed by a value. You signal the end of the list by passing a nil value.

Return Value

A CIFilter object whose input values are initialized.

Availability
  • Available in OS X v10.4 and later.
Declared In
CIFilter.h

localizedDescriptionForFilterName:

Returns the localized description of a filter for display in the user interface.

+ (NSString *)localizedDescriptionForFilterName:(NSString *)filterName
Parameters
filterName

The filter name.

Return Value

The localized description of the filter.

Availability
  • Available in OS X v10.5 and later.
Declared In
CIFilter.h

localizedNameForCategory:

Returns the localized name for the specified filter category.

+ (NSString *)localizedNameForCategory:(NSString *)category
Parameters
category

A filter category.

Return Value

The localized name for the filter category.

Availability
  • Available in OS X v10.4 and later.
Declared In
CIFilter.h

localizedNameForFilterName:

Returns the localized name for the specified filter name.

+ (NSString *)localizedNameForFilterName:(NSString *)filterName
Parameters
filterName

A filter name.

Return Value

The localized name for the filter.

Availability
  • Available in OS X v10.4 and later.
Related Sample Code
Declared In
CIFilter.h

localizedReferenceDocumentationForFilterName:

Returns the location of the localized reference documentation that describes the filter.

+ (NSURL *)localizedReferenceDocumentationForFilterName:(NSString *)filterName
Parameters
filterName

The filter name.

Return Value

A URL that specifies the location of the localized documentation, or nil if the filter does not provide localized reference documentation.

Discussion

The URL can be a local file or a remote document on a web server. Because filters created prior to OS X v10.5 could return nil, you should be make sure that your code handles this case gracefully.

Availability
  • Available in OS X v10.5 and later.
Declared In
CIFilter.h

registerFilterName:constructor:classAttributes:

Publishes a custom filter that is not packaged as an image unit.

+ (void)registerFilterName:(NSString *)name constructor:(id)anObject classAttributes:(NSDictionary *)attributes
Parameters
name

A string object that specifies the name of the filter you want to publish.

anObject

A constructor object that implements the filterWithName method.

attributes

A dictionary that contains the class display name and filter categories attributes along with the appropriate value for each attributes. That is, the kCIAttributeFilterDisplayName attribute and a string that specifies the display name, and the kCIAttributeFilterCategories and an array that specifies the categories to which the filter belongs (such as kCICategoryStillImage and kCICategoryDistortionEffect). All other attributes for the filter should be returned by the custom attributes method implement by the filter.

Discussion

In most cases you don’t need to use this method because the preferred way to register a custom filter that you write is to package it as an image unit. You do not need to use this method for a filter packaged as an image unit because you register your filter using the CIPlugInRegistration protocol. (See Core Image Programming Guide for additional details.)

Availability
  • Available in OS X v10.4 and later.
Related Sample Code
Declared In
CIFilter.h

serializedXMPFromFilters:inputImageExtent:

Serializes filter parameters into XMP form that is suitable for embedding in an image.

+ (NSData*)serializedXMPFromFilters:(NSArray *)filters inputImageExtent:(CGRect)extent
Parameters
filters

The array of filters to serialize. See Discussion for the filters that can be serialized.

extent

The extent of the input image to the filter.

Discussion

At this time the only filters classes that can be serialized using this method are, CIAffineTransform, CICrop, and the filters returned by the CIImage methods autoAdjustmentFilters and autoAdjustmentFiltersWithOptions:. The parameters of other filter classes will not be serialized.

Availability
  • Available in OS X v10.9 and later.
Declared In
CIFilter.h

Instance Methods

apply:

Produces a CIImage object by applying a kernel function.

- (CIImage *)apply:(CIKernel *)k, ...
Parameters
k

A CIKernel object that contains a kernel function.

A list of arguments to supply to the kernel function. The supplied arguments must be type-compatible with the function signature of the kernel function. The list of arguments must be terminated by the nil object.

Discussion

If you are implementing a custom filter, this method needs to be called from within the outputImage method in order to apply your kernel function to the CIImage object. For example, if the kernel function has this signature:

kernel vec4 brightenEffect (sampler src, float k)

You would supply two arguments after the k argument to the apply:k, .. method. In this case, the first argument must be a sampler and the second a floating-point value. For more information on kernels, see Core Image Kernel Language Reference.

Availability
  • Available in OS X v10.4 and later.
Declared In
CIFilter.h

apply:arguments:options:

Produces a CIImage object by applying arguments to a kernel function and using options to control how the kernel function is evaluated.

- (CIImage *)apply:(CIKernel *)k arguments:(NSArray *)args options:(NSDictionary *)dict
Parameters
k

A CIKernel object that contains a kernel function.

args

The arguments that are type compatible with the function signature of the kernel function.

dict

A dictionary that contains options (key-value pairs) to control how the kernel function is evaluated.

Return Value

The CIImage object produced by a filter.

Discussion

If you are implementing a custom filter, this method needs to be called from within the outputImage method in order to apply your kernel function to the CIImage object. You can pass any of the keys defined in “Options for Applying a Filter”, along with appropriate values, into the options dictionary.

Availability
  • Available in OS X v10.4 and later.
See Also
Declared In
CIFilter.h

attributes

Returns a dictionary of key-value pairs that describe the filter.

- (NSDictionary *)attributes
Return Value

A dictionary that contains a key for each input and output parameter for the filter. Each key is a dictionary that contains all the attributes of an input or output parameter.

Discussion

For example, the attributes dictionary for the CIColorControls filter contains the following information:

CIColorControls:
{
    CIAttributeFilterCategories = (
        CICategoryColorAdjustment,
        CICategoryVideo,
        CICategoryStillImage,
        CICategoryInterlaced,
        CICategoryNonSquarePixels,
        CICategoryBuiltIn
    );
    CIAttributeFilterDisplayName = "Color Controls";
    CIAttributeFilterName = CIColorControls;
    inputBrightness = {
        CIAttributeClass = NSNumber;
        CIAttributeDefault = 0;
        CIAttributeIdentity = 0;
        CIAttributeMin = -1;
        CIAttributeSliderMax = 1;
        CIAttributeSliderMin = -1;
        CIAttributeType = CIAttributeTypeScalar;
    };
    inputContrast = {
        CIAttributeClass = NSNumber;
        CIAttributeDefault = 1;
        CIAttributeIdentity = 1;
        CIAttributeMin = 0.25;
        CIAttributeSliderMax = 4;
        CIAttributeSliderMin = 0.25;
        CIAttributeType = CIAttributeTypeScalar;
    };
    inputImage = {CIAttributeClass = CIImage; };
    inputSaturation = {
        CIAttributeClass = NSNumber;
        CIAttributeDefault = 1;
        CIAttributeIdentity = 1;
        CIAttributeMin = 0;
        CIAttributeSliderMax = 3;
        CIAttributeSliderMin = 0;
        CIAttributeType = CIAttributeTypeScalar;
    };
    outputImage = {CIAttributeClass = CIImage; };
}
Availability
  • Available in OS X v10.4 and later.
Declared In
CIFilter.h

inputKeys

Returns an array that contains the names of the input parameters to the filter.

- (NSArray *)inputKeys
Return Value

An array that contains the names of all input parameters to the filter.

Availability
  • Available in OS X v10.4 and later.
Related Sample Code
Declared In
CIFilter.h

outputKeys

Returns an array that contains the names of the output parameters for the filter.

- (NSArray *)outputKeys
Return Value

An array that contains the names of all output parameters from the filter.

Availability
  • Available in OS X v10.4 and later.
Declared In
CIFilter.h

setDefaults

Sets all input values for a filter to default values.

- (void)setDefaults
Discussion

Input values whose default values are not defined are left unchanged.

Availability
  • Available in OS X v10.4 and later.
Declared In
CIFilter.h

Constants

Filter Attribute Keys

Attributes for a filter and its parameters.

extern NSString *kCIAttributeFilterName;
extern NSString *kCIAttributeFilterDisplayName;
extern NSString *kCIAttributeDescription;
extern NSString *kCIAttributeReferenceDocumentation;
extern NSString *kCIAttributeFilterCategories;
extern NSString *kCIAttributeClass;
extern NSString *kCIAttributeType;
extern NSString *kCIAttributeMin;
extern NSString *kCIAttributeMax;
extern NSString *kCIAttributeSliderMin;
extern NSString *kCIAttributeSliderMax;
extern NSString *kCIAttributeDefault;
extern NSString *kCIAttributeIdentity;
extern NSString *kCIAttributeName;
extern NSString *kCIAttributeDisplayName;
Constants
kCIAttributeFilterName

The filter name, specified as an NSString object.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeFilterDisplayName

The localized version of the filter name that is displayed in the user interface.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeDescription

The localized description of the filter. This description should inform the end user what the filter does and be short enough to display in the user interface for the filter. It is not intended to be technically detailed.

Available in OS X v10.5 and later.

Declared in CIFilter.h.

kCIAttributeReferenceDocumentation

The localized reference documentation for the filter. The reference should provide developers with technical details.

Available in OS X v10.5 and later.

Declared in CIFilter.h.

kCIAttributeFilterCategories

An array of filter category keys that specifies all the categories in which the filter is a member.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeClass

The class name of the filter.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeType

One of the attribute types described in “Data Type Attributes.”

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeMin

The minimum value for a filter parameter, specified as a floating-point value.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeMax

The maximum value for a filter parameter, specified as a floating-point value.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeSliderMin

The minimum value, specified as a floating-point value, to use for a slider that controls input values for a filter parameter.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeSliderMax

The maximum value, specified as a floating-point value, to use for a slider that controls input values for a filter parameter.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeDefault

The default value, specified as a floating-point value, for a filter parameter.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeIdentity

If supplied as a value for a parameter, the parameter has no effect on the input image.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeName

The name of the attribute.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeDisplayName

The localized display name of the attribute.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

Discussion

Attribute keys are used for the attribute dictionary of a filter. Most entries in the attribute dictionary are optional. The attribute CIAttributeFilterName is mandatory. For a parameter, the attribute kCIAttributeClass is mandatory because it specifies the class name of the filter.

A parameter of type NSNumber does not necessarily need the attributes kCIAttributeMin and kCIAttributeMax. These attributes are not present when the parameter has no upper or lower bounds. For example, the Gaussian blur filter has a radius parameter with a minimum of 0 but no maximum value to indicate that all nonnegative values are valid.

Declared In
CIFilter.h

Data Type Attributes

Numeric data types.

extern NSString *kCIAttributeTypeTime;
extern NSString *kCIAttributeTypeScalar;
extern NSString *kCIAttributeTypeDistance;
extern NSString *kCIAttributeTypeAngle;
extern NSString *kCIAttributeTypeBoolean;
extern NSString *kCIAttributeTypeInteger;
extern NSString *kCIAttributeTypeCount;
Constants
kCIAttributeTypeTime

A parametric time for transitions, specified as a floating-point value in the range of 0.0 to 1.0.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeTypeScalar

A scalar value.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeTypeDistance

A distance.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeTypeAngle

An angle.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeTypeBoolean

A Boolean value.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeTypeInteger

An integer value.

Available in OS X v10.5 and later.

Declared in CIFilter.h.

kCIAttributeTypeCount

A positive integer value.

Available in OS X v10.5 and later.

Declared in CIFilter.h.

Declared In
CIFilter.h

Vector Quantity Attributes

Vector data types.

extern NSString *kCIAttributeTypePosition;
extern NSString *kCIAttributeTypeOffset;
extern NSString *kCIAttributeTypePosition3;
extern NSString *kCIAttributeTypeRectangle
Constants
kCIAttributeTypePosition

A two-dimensional location in the working coordinate space. (A 2-element vector type.)

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeTypeOffset

An offset. (A 2-element vector type.)

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeTypePosition3

A three-dimensional location in the working coordinate space. (A 3-element vector type.)

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeTypeRectangle

A Core Image vector that specifies the x and y values of the rectangle origin, and the width (w) and height (h) of the rectangle. The vector takes the form [x, y, w, h]. (A 4-element vector type.)

Available in OS X v10.4 and later.

Declared in CIFilter.h.

Declared In
CIFilter.h

Color Attribute Keys

Color types.

extern NSString *kCIAttributeTypeOpaqueColor;
extern NSString *kCIAttributeTypeGradient;
Constants
kCIAttributeTypeOpaqueColor

A Core Image color (CIColor object) that specifies red, green, and blue component values. Use this key for colors with no alpha component. If the key is not present, Core Image assumes color with alpha.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIAttributeTypeGradient

An n-by-1 gradient image used to describe a color ramp.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

Declared In
CIFilter.h

Filter Category Keys

Categories of filters.

extern NSString *kCICategoryDistortionEffect;
extern NSString *kCICategoryGeometryAdjustment;
extern NSString *kCICategoryCompositeOperation;
extern NSString *kCICategoryHalftoneEffect;
extern NSString *kCICategoryColorAdjustment;
extern NSString *kCICategoryColorEffect;
extern NSString *kCICategoryTransition;
extern NSString *kCICategoryTileEffect;
extern NSString *kCICategoryGenerator;
extern NSString *kCICategoryReduction;
extern NSString *kCICategoryGradient;
extern NSString *kCICategoryStylize;
extern NSString *kCICategorySharpen;
extern NSString *kCICategoryBlur;
extern NSString *kCICategoryVideo;
extern NSString *kCICategoryStillImage;
extern NSString *kCICategoryInterlaced;
extern NSString *kCICategoryNonSquarePixels;
extern NSString *kCICategoryHighDynamicRange ;
extern NSString *kCICategoryBuiltIn;
extern NSString *kCICategoryFilterGenerator;
Constants
kCICategoryDistortionEffect

A filter that reshapes an image by altering its geometry to create a 3D effect. Using distortion filters, you can displace portions of an image, apply lens effects, make a bulge in an image, and perform other operation to achieve an artistic effect.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryGeometryAdjustment

A filter that changes the geometry of an image. Some of these filters are used to warp an image to achieve an artistic effects, but these filters can also be used to correct problems in the source image. For example, you can apply an affine transform to straighten an image that is rotated with respect to the horizon.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryCompositeOperation

A filter operates on two image sources, using the color values of one image to operate on the other. Composite filters perform computations such as computing maximum values, minimum values, and multiplying values between input images. You can use compositing filters to add effects to an image, crop an image, and achieve a variety of other effects.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryHalftoneEffect

A filter that simulates a variety of halftone screens, to mimic the halftone process used in print media. The output of these filters has the familiar “newspaper” look of the various dot patterns. Filters are typically named after the pattern created by the virtual halftone screen, such as circular screen or hatched screen.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryColorAdjustment

A filter that changes color values. Color adjustment filters are used to eliminate color casts, adjust hue, and correct brightness and contrast. Color adjustment filters do not perform color management; ColorSync performs color management. You can use Quartz 2D to specify the color space associated with an image. For more information, see Color Management Overview and Quartz 2D Programming Guide.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryColorEffect

A filter that modifies the color of an image to achieve an artistic effect. Examples of color effect filters include filters that change a color image to a sepia image or a monochrome image or that produces such effects as posterizing.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryTransition

A filter that provides a bridge between two or more images by applying a motion effect that defines how the pixels of a source image yield to that of the destination image.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryTileEffect

A filter that typically applies an effect to an image and then create smaller versions of the image (tiles), which are then laid out to create a pattern that’s infinite in extent.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryGenerator

A filter that generates a pattern, such as a solid color, a checkerboard, or a star shine. The generated output is typically used as input to another filter.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryReduction

A filter that reduces image data. These filters are used to solve image analysis problems.

Available in OS X v10.5 and later.

Declared in CIFilter.h.

kCICategoryGradient

A filter that generates a fill whose color varies smoothly. Exactly how color varies depends on the type of gradient—linear, radial, or Gaussian.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryStylize

A filter that makes a photographic image look as if it was painted or sketched. These filters are typically used alone or in combination with other filters to achieve artistic effects.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategorySharpen

A filter that sharpens images, increasing the contrast between the edges in an image. Examples of sharpen filters are unsharp mask and sharpen luminance.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryBlur

A filter that softens images, decreasing the contrast between the edges in an image. Examples of blur filters are Gaussian blur and zoom blur.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryVideo

A filter that works on video images.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryStillImage

A filter that works on still images.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryInterlaced

A filter that works on interlaced images.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryNonSquarePixels

A filter that works on non-square pixels.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryHighDynamicRange

A filter that works on high dynamic range pixels.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryBuiltIn

A filter provided by Core Image. This distinguishes built-in filters from plug-in filters.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCICategoryFilterGenerator

A filter created by chaining several filters together and then packaged as a CIFilterGenerator object.

Available in OS X v10.5 and later.

Declared in CIFilter.h.

Declared In
CIFilter.h

Options for Applying a Filter

Options that control the application of a custom Core Image filter.

extern NSString *kCIApplyOptionExtent;
extern NSString *kCIApplyOptionDefinition;
extern NSString *kCIApplyOptionUserInfo;
extern NSString *kCIApplyOptionColorSpace;
Constants
kCIApplyOptionExtent

The size of the produced image. The associated value is a four-element array (NSArray) that specifies the x-value of the rectangle origin, the y-value of the rectangle origin, and the width and height.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIApplyOptionDefinition

The domain of definition (DOD) of the produced image. The associated value is either a Core Image filter shape or a four-element array (NSArray) that specifies a rectangle.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIApplyOptionUserInfo

Information needed by a callback. The associated value is an object that Core Image will pass to any callbacks invoked for that filter.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

kCIApplyOptionColorSpace

The color space of the produced image. The associated value must be an RGB CGColorSpaceRef object. If not specified, the output of the kernel is in the working color space of the Core Image context used to render the image.

Available in OS X v10.4 and later.

Declared in CIFilter.h.

Discussion

Use these constants only when creating a custom filter for which you are writing the kernel. For more information, see Core Image Programming Guide. The example on creating a custom filter shows how to use these options.

Declared In
CIFilter.h

User Interface Control Options

Sets of controls for various user scenarios.

extern NSString *kCIUIParameterSet;
extern NSString *kCIUISetBasic;
extern NSString *kCIUISetIntermediate;
extern NSString *kCIUISetAdvanced;
extern NSString *kCIUISetDevelopment;
Constants
kCIUIParameterSet

The set of input parameters to use. The associated value can be kCIUISetBasic, kCIUISetIntermediate, kCIUISetAdvanced, or kCIUISetDevelopment.

Available in OS X v10.5 and later.

Declared in CIFilter.h.

kCIUISetBasic

Controls that are appropriate for a basic user scenario, that is, the minimum of settings to control the filter.

Available in OS X v10.5 and later.

Declared in CIFilter.h.

kCIUISetIntermediate

Controls that are appropriate for an intermediate user scenario.

Available in OS X v10.5 and later.

Declared in CIFilter.h.

kCIUISetAdvanced

Controls that are appropriate for an advanced user scenario.

Available in OS X v10.5 and later.

Declared in CIFilter.h.

kCIUISetDevelopment

Controls that should be visible only for development purposes.

Available in OS X v10.5 and later.

Declared in CIFilter.h.

Discussion

You can use these constants to specify the controls that you want associated with each user scenario. For example, for a filter that has many input parameters you can choose a small set of input parameters that the typical consumer can control and set the other input parameters to default values. For the same filter, however, you can choose to allow professional customers to control all the input parameters.

Declared In
CIFIlter.h

Filter Parameter Keys

Keys for input parameters to filters.

extern NSString *kCIOutputImageKey;
extern NSString *kCIInputBackgroundImageKey;
extern NSString *kCIInputImageKey;
extern NSString *kCIInputTimeKey;
extern NSString *kCIInputTransformKey;
extern NSString *kCIInputScaleKey;
extern NSString *kCIInputAspectRatioKey;
extern NSString *kCIInputCenterKey;
extern NSString *kCIInputRadiusKey;
extern NSString *kCIInputAngleKey;
extern NSString *kCIInputRefractionKey;
extern NSString *kCIInputWidthKey;
extern NSString *kCIInputSharpnessKey;
extern NSString *kCIInputIntensityKey;
extern NSString *kCIInputEVKey;
extern NSString *kCIInputSaturationKey;
extern NSString *kCIInputColorKey;
extern NSString *kCIInputBrightnessKey;
extern NSString *kCIInputContrastKey;
extern NSString *kCIInputGradientImageKey;
extern NSString *kCIInputMaskImageKey;
extern NSString *kCIInputShadingImageKey;
extern NSString *kCIInputTargetImageKey;
extern NSString *kCIInputExtentKey;
Constants
kCIOutputImageKey

A key for the CIImage object produced by a filter.

Available in OS X v10.5 and later. Available in iOS 5.0 and later.

Declared in CIFilter.h.

kCIInputBackgroundImageKey

A key for the CIImage object to use as a background image.

Available in OS X v10.5 and later. Available in iOS 5.0 and later.

Declared in CIFilter.h.

kCIInputImageKey

A key for the CIImage object to use as an input image. For filters that also use a background image, this key refers to the foreground image.

Available in OS X v10.5 and later. Available in iOS 5.0 and later.

Declared in CIFilter.h.

kCIInputTimeKey

A key for z scalar value (NSNumber) that specifies a time.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputTransformKey

A key for an NSAffineTransform object that specifies a transformation to apply.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputScaleKey

A key for a scalar value (NSNumber) that specifies the amount of the effect.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputAspectRatioKey

A key for a scalar value (NSNumber) that specifies a ratio.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputCenterKey

A key for a CIVector object that specifies the center of the area, as x and y- coordinates, to be filtered.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputRadiusKey

A key for a scalar value (NSNumber) that specifies that specifies the distance from the center of an effect.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputAngleKey

A key for a scalar value (NSNumber) that specifies an angle.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputRefractionKey

A key for a scalar value (NSNumber) that specifies the index of refraction of the material (such as glass) used in the effect.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputWidthKey

A key for a scalar value (NSNumber) that specifies the width of the effect.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputSharpnessKey

A key for a scalar value (NSNumber) that specifies the amount of sharpening to apply.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputIntensityKey

A key for a scalar value (NSNumber) that specifies an intensity value.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputEVKey

A key for a scalar value (NSNumber) that specifies how many F-stops brighter or darker the image should be.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputSaturationKey

A key for a scalar value (NSNumber) that specifies the amount to adjust the saturation.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputColorKey

A key for a CIColor object that specifies a color value.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputBrightnessKey

A key for a scalar value (NSNumber) that specifies a brightness level.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputContrastKey

A key for a scalar value (NSNumber) that specifies a contrast level.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputGradientImageKey

A key for a CIImage object that specifies an environment map with alpha. Typically, this image contains highlight and shadow.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputMaskImageKey

A key for a CIImage object to use as a mask.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputShadingImageKey

A key for a CIImage object that specifies an environment map with alpha values. Typically this image contains highlight and shadow.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputTargetImageKey

A key for a CIImage object that is the target image for a transition.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

kCIInputExtentKey

A key for a CIVector object that specifies a rectangle that defines the extent of the effect.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIFilter.h.

Discussion

These keys represent some of the most commonly used input parameters. A filter can use other kinds of input parameters.

Declared In
CIFIlter.h

RAW Image Options

Options for creating a CIFilter object from RAW image data.

extern NSString * const kCIInputDecoderVersionKey;
extern NSString * const kCISupportedDecoderVersionsKey;
extern NSString * const kCIInputBoostKey;
extern NSString * const kCIInputNeutralChromaticityXKey;
extern NSString * const kCIInputNeutralChromaticityYKey;
extern NSString * const kCIInputNeutralTemperatureKey;
extern NSString * const kCIInputNeutralTintKey;
extern NSString * const kCIInputNeutralLocation;
extern NSString * const kCIInputScaleFactorKey;
extern NSString * const kCIInputAllowDraftModeKey;
extern NSString * const kCIInputIgnoreImageOrientationKey;
extern NSString * const kCIInputImageOrientationKey;
extern NSString * const kCIInputEnableSharpeningKey;
extern NSString * const kCIInputEnableChromaticNoiseTrackingKey;
extern NSString * const kCIInputNoiseReductionAmountKey;
extern NSString * const kCIInputBoostShadowAmountKey;
extern NSString * const kCIInputBiasKey;
extern NSString * const kCIInputLinearSpaceFilter;
extern NSString * const kCIOutputNativeSizeKey;
extern NSString * const kCIActiveKeys;
Constants
kCIInputDecoderVersionKey

A key for the version number of the method to be used for decoding. A newly initialized object defaults to the newest available decoder version for the given image type. You can request an alternative, older version to maintain compatibility with older releases. Must be one of kCISupportedDecoderVersions, otherwise a nil output image is generated. The associated value must be an NSNumber object that specifies an integer value in range of 0 to the current decoder version. When you request a specific version of the decoder, Core Image produces an image that is visually the same across different versions of the operating system. Core Image, however, does not guarantee that the same bits are produced across different versions of the operating system. That’s because the rounding behavior of floating-point arithmetic can vary due to differences in compilers or hardware. Note that this option has no effect if the image used for initialization is not RAW.

Available in OS X v10.5 and later.

Declared in CIRAWFilter.h.

kCISupportedDecoderVersionsKey

A key for the supported decoder versions. The associated value is an NSArray object that contains all supported decoder versions for the given image type, sorted in increasingly newer order. Each entry is an NSDictionary object that contains key-value pairs. All entries represent a valid version identifier that can be passed as the kCIDecoderVersion value for the key kCIDecoderMethodKey. Version values are read-only; attempting to set this value raises an exception. Currently, the only defined key is @"version" which has as its value an NSString that uniquely describing a given decoder version. This string might not be suitable for user interface display..

Available in OS X v10.5 and later.

Declared in CIRAWFilter.h.

kCIInputBoostKey

A key for the the amount of boost to apply to an image. The associated value is a floating-point value packaged as an NSNumber object. The value must be in the range of 0...1. A value of 0 indicates no boost, that is, a linear response. The default value is 1, which indicates full boost.

Available in OS X v10.5 and later.

Declared in CIRAWFilter.h.

kCIInputNeutralChromaticityXKey

The x value of the chromaticity. The associated value is a floating-point value packaged as an NSNumber object. You can query this value to get the current x value for neutral x, y.

Available in OS X v10.5 and later.

Declared in CIRAWFilter.h.

kCIInputNeutralChromaticityYKey

The y value of the chromaticity. The associated value is a floating-point value packaged as an NSNumber object. You can query this value to get the current y value for neutral x, y.

Available in OS X v10.5 and later.

Declared in CIRAWFilter.h.

kCIInputNeutralTemperatureKey

A key for neutral temperature. The associated value is a floating-point value packaged as an NSNumber object. You can query this value to get the current temperature value.

Available in OS X v10.5 and later.

Declared in CIRAWFilter.h.

kCIInputNeutralTintKey

A key for the neutral tint. The associated value is a floating-point value packaged as an NSNumber object. Use this key to set or fetch the temperature and tint values. You can query this value to get the current tint value.

Available in OS X v10.5 and later.

Declared in CIRAWFilter.h.

kCIInputNeutralLocationKey

A key for the neutral position. Use this key to set the location in geometric coordinates of the unrotated output image that should be used as neutral. You cannot query this value; it is undefined for reading. The associated value is a two-element CIVector object that specifies the location (x, y).

Available in OS X v10.5 and later.

Declared in CIRAWFilter.h.

kCIInputScaleFactorKey

A key for the scale factor. The associated value is a floating-point value packaged as an NSNumber object that specifies the desired scale factor at which the image will be drawn. Setting this value can greatly improve the drawing performance. A value of 1 is the identity. In some cases, if you change the scale factor and enable draft mode, performance can decrease. See kCIInputAllowDraftModeKey.

Available in OS X v10.5 and later.

Declared in CIRAWFilter.h.

kCIInputAllowDraftModeKey

A key for allowing draft mode. The associated value is a Boolean value packaged as an NSNumber object. It’s best not to use draft mode if the image needs to be drawn without draft mode at a later time, because changing the value from YES to NO is an expensive operation. If the optional scale factor is smaller than a certain value, additionally setting draft mode can improve image decoding speed without any perceivable loss of quality. However, turning on draft mode does not have any effect if the scale factor is not below this threshold.

Available in OS X v10.5 and later.

Declared in CIRAWFilter.h.

kCIInputIgnoreImageOrientationKey

A key for specifying whether to ignore the image orientation. The associated value is a Boolean value packaged as an NSNumber object. The default value is NO. An image is usually loaded in its proper orientation, as long as the associated metadata records its orientation. For special purposes you might want to load the image in its physical orientation. The exact meaning of "physical orientation” is dependent on the specific image.

Available in OS X v10.5 and later.

Declared in CIRAWFilter.h.

kCIInputImageOrientationKey

A key for the image orientation. The associated value is an integer value packaged as an NSNumber object. Valid values are in range 1...8 and follow the EXIF specification. The value is disregarded when the kCIIgnoreImageOrientationKey flag is set. You can change the orientation of the image by overriding this value. By changing this value you can easily rotate an image in 90-degree increments.

Available in OS X v10.5 and later.

Declared in CIRAWFilter.h.

kCIInputEnableSharpeningKey

A key for the sharpening state. The associated value must be an NSNumber object that specifies a BOOL value (YES or NO). The default is YES. This option has no effect if the image used for initialization is not RAW.

Available in OS X v10.5 and later.

Declared in CIRAWFilter.h.

kCIInputEnableChromaticNoiseTrackingKey

A key for progressive chromatic noise tracking (based on ISO and exposure time). The associated value must be an NSNumber object that specifies a BOOL value (YES or NO). The default is YES. This option has no effect if the image used for initialization is not RAW.

Available in OS X v10.5 and later.

Declared in CIRAWFilter.h.

kCIInputNoiseReductionAmountKey

A key for the amount to reduce noise in the image. The associated value must be an NSNumber object that specifies a floating-point value between 0.0 and 1.0. The value has no effect if the image used for initialization is not RAW.

Available in OS X v10.7 and later. Not available in iOS.

Declared in CIRAWFilter.h.

kCIInputBoostShadowAmountKey

A key for the amount to boost the shadow areas of the image. The associated value must be an NSNumber object that specifies floating-point value. The value has no effect if the image used for initialization is not RAW.

Available in OS X v10.5 and later.

Declared in CIRAWFilter.h.

kCIInputBiasKey

A key for the simple bias value to use along with the exposure adjustment (kCIInputEVKey). The associated value must be an NSNumber object that specifies floating-point value. The value has no effect if the image used for initialization is not RAW.

Available in OS X v10.5 and later.

Declared in CIRAWFilter.h.

kCIInputLinearSpaceFilter

A key for the filter to apply to the image while it is temporarily in a linear color space as part of RAW image processing. The associated value must be a CIFilter object.

Available in OS X v10.7 and later. Not available in iOS.

Declared in CIRAWFilter.h.

kCIOutputNativeSizeKey

A key for the full native size of the original, non-transformed RAW image. The associated value is a CIVector object whose X and Y values are the image’s width and height. This key is read-only.

Available in OS X v10.5 and later. Not available in iOS.

Declared in CIRAWFilter.h.

kCIActiveKeys

A key for the set of input keys available for use. The associated value is an NSSet object containing the set of input keys which may be used to affect the output image. (Depending on the input image type and the decoder version, some input keys may be unavailable.) This key is read-only.

Available in OS X v10.7 and later. Not available in iOS.

Declared in CIRAWFilter.h.

Discussion

You can also use the key kCIInputEVKey for RAW images.

Declared In
CIRAWFilter.h