ShinpuruImage

Syntactic Sugar for Accelerate/vImage and Core Image Filters

ShinpuruImage offers developers a consistent and strongly typed interface to Apple's Core Image and vImage/Accelerate image filters without the need for boilerplate code.

ShinpuruImage filters are implemented as extensions to UIImage and can be chained together with a super easy syntax:

        let image = UIImage(named: "vegas.jpg")!
            .SIFastBlur(width: 10, height: 10, backgroundColor: UIColor.redColor())
            .SIMonochrome(color: UIColor.yellowColor(), intensity: 1)
            .SIRotate(angle: 0.3, backgroundColor: UIColor.purpleColor())

Installation

ShinpuruImage consists of three Swift files and to use ShinpuruImage in your own project, you simply need to copy:

• ShinpuruImage_vImage.swift
• ShinpuruImage_CoreImage.swift
• ShinpuruImage_Chaining

Filters

Photo Effects

• func SIPhotoEffectNoir() -> UIImage Applies a preconfigured set of effects that imitate black-and-white photography film with exaggerated contrast.
• func SIPhotoEffectChrome() -> UIImage Applies a preconfigured set of effects that imitate vintage photography film with exaggerated color.
• func SIPhotoEffectFade() -> UIImage Applies a preconfigured set of effects that imitate vintage photography film with diminished color.
• func SIPhotoEffectInstant() -> UIImage Applies a preconfigured set of effects that imitate vintage photography film with distorted colors.
• func SIPhotoEffectMono() -> UIImage Applies a preconfigured set of effects that imitate black-and-white photography film with low contrast.
• func SIPhotoEffectProcess() -> UIImage Applies a preconfigured set of effects that imitate vintage photography film with emphasized cool colors.
• func SIPhotoEffectTonal() -> UIImage Applies a preconfigured set of effects that imitate black-and-white photography film without significantly altering contrast.
• func SIPhotoEffectTransfer() -> UIImage Applies a preconfigured set of effects that imitate vintage photography film with emphasized warm colors.

Color Effects

• func SIFalseColor(#color0: UIColor, color1: UIColor) -> UIImage Maps luminance to a color ramp of two colors.
• func SIPosterize(#levels: Int) -> UIImage Remaps red, green, and blue color components to the number of brightness values you specify for each color component.
• func SIMonochrome(#color: UIColor, intensity: Float) -> UIImage Remaps colors so they fall within shades of a single color.

Stylize

• func SIBloom(#radius: Float, intensity: Float) -> UIImage Softens edges and applies a pleasant glow to an image.
• func SIGloom(#radius: Float, intensity: Float) -> UIImage Dulls the highlights of an image.
• func SIPixellate(#scale: Float) -> UIImage Makes an image blocky by mapping the image to colored squares whose color is defined by the replaced pixels.

Blur

• func SIGaussianBlur(#radius: Float) -> UIImage Spreads source pixels by an amount specified by a Gaussian distribution.

Color Adjustment

• func SIColorControls(#saturation: Float, brightness: Float, contrast: Float) -> UIImage Adjusts saturation, brightness, and contrast values.
• func SIExposureAdjust(#ev: Float) -> UIImage Adjusts the exposure setting for an image similar to the way you control exposure for a camera when you change the F-stop.
• func SIGammaAdjust(#power: Float) -> UIImage Adjusts midtone brightness.
• func SIHueAdjust(#power: Float) -> UIImage Changes the overall hue, or tint, of the source pixels.
• func SIVibrance(#amount: Float) -> UIImage Adjusts the saturation of an image while keeping pleasing skin tones.
• func SIWhitePointAdjust(#color: UIColor) -> UIImage Adjusts the reference white point for an image and maps all colors in the source using the new reference.

Morphology functions

• func SIDilateFilter(#kernel: [UInt8]) -> UIImage Dilates an object
• func SIErodeFilter(#kernel: [UInt8]) -> UIImage Erodes an object
• func SIMaxFilter(#width: Int, height: Int) -> UIImage The morphological operation Max is a special case of the dilation operation whereby all the elements of the kernel have the same value.
• func SIMinFilter(#width: Int, height: Int) -> UIImage The morphological operation Min is a special case of the erosion operation whereby all the elements of the kernel have the same value.

High Level Geometry Functions

• func SIScale(#scaleX: Float, scaleY: Float) -> UIImage Resize the input image
• func SIRotate(#angle: Float, backgroundColor: UIColor = UIColor.blackColor()) -> UIImage Rotate the input image around a center point by any amount
• func SIRotateNinety(rotation: RotateNinety, backgroundColor: UIColor = UIColor.blackColor()) -> UIImage Rotate an image by 0, 90, 180 or 270 degrees
• func SIHorizontalReflect() -> UIImage Reflect an image across a mirror plane at the center of the image
• func SIVerticalReflect() -> UIImage Reflect an image across a mirror plane at the center of the image

Convolution

• func SIBoxBlur(#width: Int, height: Int, backgroundColor: UIColor = UIColor.blackColor()) -> UIImage Apply a mean filter to the image.
• func SIFastBlur(#width: Int, height: Int, backgroundColor: UIColor = UIColor.blackColor()) -> UIImage Apply a tent filter to the image.
• func SIConvolutionFilter(#kernel: [Int16], divisor: Int, backgroundColor: UIColor = UIColor.blackColor()) -> UIImage All four channel convolution function

Histogram

• func SIHistogramCalculation() -> (alpha: [UInt], red: [UInt], green: [UInt], blue: [UInt]) Returns a tuple containing four arrays of 256 UInt representing the histogram of the supplied image

Demo Application

The demo app contains three components:

• RotateAndScale - demonstrates chained SIScale() and SIRotate() controlled by three numeric sliders
• ColorControls - demonstrates SIColorControls controlled by three numeric sliders
• Histogram - uses ios-charts to demonstrate the use of SIHistogramCalculation and the performance benefits of using fast filter chaining.

Filter Chaining

For the best perfomance when chaining image filters together, Shinpuru Image includes a SIFastChainableImage type that prevents the chain from converting to UIImage between individual chained filters. The syntax is slightly different and requires the source UIImage to be cast to a SIFastChainableImage and the final output to be converted back to a UIImage:

            let image = UIImage(named: "oculista.jpg")!

            let chained = SIFastChainableImage(image: image)
                .SIPhotoEffectFade()
                .SIGaussianBlur(radius: 5)
                .SIFalseColor(color0: UIColor.blueColor(), color1: UIColor.redColor())
                .SIPixellate(scale: 5)
                .toUIImage()

For complex chains of filters, using SIFastChainableImage can be four or fives times faster. However, in this mode, color management is turned off.

Blurring Images

To blur an image you have three options: a true Gaussian blur (SIGaussianBlur), a box blur (SIBoxBlur) and ShinpuruImage fast blur (SIFastBlur) which is based on vImageTentConvolve. Of the three, I've found SIBoxBlur to be the fastest and SIGaussianBlur to be the slowest. It's worth using measureBlock() to do your own performance testing.