CoreImage Filters

Core Image Filter Example

Objective-C

Just log this see how to use a particular filter

NSArray *properties = [CIFilter filterNamesInCategory:kCICategoryBuiltIn];              
        
 for (NSString *filterName in properties) 
 {
 CIFilter *fltr = [CIFilter filterWithName:filterName];
 NSLog(@"%@", [fltr attributes]);
 } 

In case of CISepiaTone the system log is as follows

CIAttributeFilterDisplayName = "Sepia Tone";
CIAttributeFilterName = CISepiaTone;
    CIAttributeReferenceDocumentation = "http://developer.apple.com/cgi-bin/apple_ref.cgi?apple_ref=//apple_ref/doc/filter/ci/CISepiaTone";
    inputImage =     {
        CIAttributeClass = CIImage;
        CIAttributeDescription = "The image to use as an input image. For filters that also use a background image, this is the foreground image.";
        CIAttributeDisplayName = Image;
        CIAttributeType = CIAttributeTypeImage;
    };
    inputIntensity =     {
        CIAttributeClass = NSNumber;
        CIAttributeDefault = 1;
        CIAttributeDescription = "The intensity of the sepia effect. A value of 1.0 creates a monochrome sepia image. A value of 0.0 has no effect on the image.";
        CIAttributeDisplayName = Intensity;
        CIAttributeIdentity = 0;
        CIAttributeMin = 0;
        CIAttributeSliderMax = 1;
        CIAttributeSliderMin = 0;
        CIAttributeType = CIAttributeTypeScalar;
    };
}

Using the above system log we set up the filter as below:

   CIImage *beginImage = [CIImage imageWithCGImage:[myImageView.image CGImage]];
    CIContext *context = [CIContext contextWithOptions:nil];
    //select Filter Name and Intensity
    CIFilter *filter = [CIFilter filterWithName:@"CISepiaTone" keysAndValues: kCIInputImageKey, beginImage, @"inputIntensity", [NSNumber numberWithFloat:0.8], nil];
    CIImage *outputImage = [filter outputImage];
    
    CGImageRef cgimg = [context createCGImage:outputImage fromRect:[outputImage extent]];
    UIImage *newImg = [UIImage imageWithCGImage:cgimg];
    
    [myImageView1 setImage:newImg];
    
    CGImageRelease(cgimg);

Image generated by the above code

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An alternative way to set up a filter

UIImageView *imageView1=[[UIImageView alloc]initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height/2)];
UIImageView *imageView2=[[UIImageView alloc]initWithFrame:CGRectMake(0, self.view.frame.size.height/2, self.view.frame.size.width, self.view.frame.size.height/2)];
imageView1.image=[UIImage imageNamed:@"image.png"];

CIImage *beginImage = [CIImage imageWithCGImage:[imageView1.image CGImage]];
CIContext *context = [CIContext contextWithOptions:nil];
//select Filter Name and Intensity

CIFilter *filter = [CIFilter filterWithName:@"CIColorPosterize"];
[filter setValue:beginImage forKey:kCIInputImageKey];
[filter setValue:[NSNumber numberWithFloat:8.0] forKey:@"inputLevels"];
CIImage *outputImage = [filter outputImage];

CGImageRef cgimg = [context createCGImage:outputImage fromRect:[outputImage extent]];
UIImage *newImg = [UIImage imageWithCGImage:cgimg];

[imageView2 setImage:newImg];

CGImageRelease(cgimg);
[self.view addSubview:imageView1];
[self.view addSubview:imageView2];

Image generated from this code

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All Available Filters are as below

/* CIAccordionFoldTransition,
    CIAdditionCompositing,
    CIAffineClamp,
    CIAffineTile,
    CIAffineTransform,
    CIAreaAverage,
    CIAreaHistogram,
    CIAreaMaximum,
    CIAreaMaximumAlpha,
    CIAreaMinimum,
    CIAreaMinimumAlpha,
    CIAztecCodeGenerator,
    CIBarsSwipeTransition,
    CIBlendWithAlphaMask,
    CIBlendWithMask,
    CIBloom,
    CIBoxBlur,
    CIBumpDistortion,
    CIBumpDistortionLinear,
    CICheckerboardGenerator,
    CICircleSplashDistortion,
    CICircularScreen,
    CICircularWrap,
    CICMYKHalftone,
    CICode128BarcodeGenerator,
    CIColorBlendMode,
    CIColorBurnBlendMode,
    CIColorClamp,
    CIColorControls,
    CIColorCrossPolynomial,
    CIColorCube,
    CIColorCubeWithColorSpace,
    CIColorDodgeBlendMode,
    CIColorInvert,
    CIColorMap,
    CIColorMatrix,
    CIColorMonochrome,
    CIColorPolynomial,
    CIColorPosterize,
    CIColumnAverage,
    CIComicEffect,
    CIConstantColorGenerator,
    CIConvolution3X3,
    CIConvolution5X5,
    CIConvolution7X7,
    CIConvolution9Horizontal,
    CIConvolution9Vertical,
    CICopyMachineTransition,
    CICrop,
    CICrystallize,
    CIDarkenBlendMode,
    CIDepthOfField,
    CIDifferenceBlendMode,
    CIDiscBlur,
    CIDisintegrateWithMaskTransition,
    CIDisplacementDistortion,
    CIDissolveTransition,
    CIDivideBlendMode,
    CIDotScreen,
    CIDroste,
    CIEdges,
    CIEdgeWork,
    CIEightfoldReflectedTile,
    CIExclusionBlendMode,
    CIExposureAdjust,
    CIFalseColor,
    CIFlashTransition,
    CIFourfoldReflectedTile,
    CIFourfoldRotatedTile,
    CIFourfoldTranslatedTile,
    CIGammaAdjust,
    CIGaussianBlur,
    CIGaussianGradient,
    CIGlassDistortion,
    CIGlassLozenge,
    CIGlideReflectedTile,
    CIGloom,
    CIHardLightBlendMode,
    CIHatchedScreen,
    CIHeightFieldFromMask,
    CIHexagonalPixellate,
    CIHighlightShadowAdjust,
    CIHistogramDisplayFilter,
    CIHoleDistortion,
    CIHueAdjust,
    CIHueBlendMode,
    CIKaleidoscope,
    CILanczosScaleTransform,
    CILenticularHaloGenerator,
    CILightenBlendMode,
    CILightTunnel,
    CILinearBurnBlendMode,
    CILinearDodgeBlendMode,
    CILinearGradient,
    CILinearToSRGBToneCurve,
    CILineOverlay,
    CILineScreen,
    CILuminosityBlendMode,
    CIMaskedVariableBlur,
    CIMaskToAlpha,
    CIMaximumComponent,
    CIMaximumCompositing,
    CIMedianFilter,
    CIMinimumComponent,
    CIMinimumCompositing,
    CIModTransition,
    CIMotionBlur,
    CIMultiplyBlendMode,
    CIMultiplyCompositing,
    CINoiseReduction,
    CIOpTile,
    CIOverlayBlendMode,
    CIPageCurlTransition,
    CIPageCurlWithShadowTransition,
    CIParallelogramTile,
    CIPDF417BarcodeGenerator,
    CIPerspectiveCorrection,
    CIPerspectiveTile,
    CIPerspectiveTransform,
    CIPerspectiveTransformWithExtent,
    CIPhotoEffectChrome,
    CIPhotoEffectFade,
    CIPhotoEffectInstant,
    CIPhotoEffectMono,
    CIPhotoEffectNoir,
    CIPhotoEffectProcess,
    CIPhotoEffectTonal,
    CIPhotoEffectTransfer,
    CIPinchDistortion,
    CIPinLightBlendMode,
    CIPixellate,
    CIPointillize,
    CIQRCodeGenerator,
    CIRadialGradient,
    CIRandomGenerator,
    CIRippleTransition,
    CIRowAverage,
    CISaturationBlendMode,
    CIScreenBlendMode,
    CISepiaTone,
    CIShadedMaterial,
    CISharpenLuminance,
    CISixfoldReflectedTile,
    CISixfoldRotatedTile,
    CISmoothLinearGradient,
    CISoftLightBlendMode,
    CISourceAtopCompositing,
    CISourceInCompositing,
    CISourceOutCompositing,
    CISourceOverCompositing,
    CISpotColor,
    CISpotLight,
    CISRGBToneCurveToLinear,
    CIStarShineGenerator,
    CIStraightenFilter,
    CIStretchCrop,
    CIStripesGenerator,
    CISubtractBlendMode,
    CISunbeamsGenerator,
    CISwipeTransition,
    CITemperatureAndTint,
    CIToneCurve,
    CITorusLensDistortion,
    CITriangleKaleidoscope,
    CITriangleTile,
    CITwelvefoldReflectedTile,
    CITwirlDistortion,
    CIUnsharpMask,
    CIVibrance,
    CIVignette,
    CIVignetteEffect,
    CIVortexDistortion,
    CIWhitePointAdjust,
    CIZoomBlur*/