How can I implement the same custom CIFilter as a Lightroom Color Grading tool for shadows, midtones, highlights and global areas?

How can I calculate polynomial coefficients for Tone Curve points: // • Red channel: (0, 0), (60, 39), (128, 128), (255, 255) // • Green channel: (0, 0), (63, 50), (128, 128), (255, 255) // • Blue channel: (0, 0), (60, 47), (119, 119), (255, 255) CIFilter: func colorCrossPolynomial(inputImage: CIImage) -> CIImage? { let colorCrossPolynomial = CIFilter.colorCrossPolynomial() let redfloatArr: [CGFloat] = [1, 1, 1, 1, 0, 0, 0, 0, 0, 0] let greenfloatArr: [CGFloat] = [0, 1, 1, 0, 0, 0, 0, 0, 0, 1] let bluefloatArr: [CGFloat] = [0, 0, 1, 0, 0, 0, 0, 1, 1, 0] colorCrossPolynomial.inputImage = inputImage colorCrossPolynomial.blueCoefficients = CIVector(values: bluefloatArr, count: bluefloatArr.count) colorCrossPolynomial.redCoefficients = CIVector(values: redfloatArr, count: redfloatArr.count) colorCrossPolynomial.greenCoefficients = CIVector(values: greenfloatArr, count: greenfloatArr.count) return colorCrossPolynomial.outputImage }

How can I use my RGB Curve points: let redCurve = [CIVector(x: 0, y: 0), CIVector(x: 0.235, y: 0.152), CIVector(x: 0.5, y: 0.5), CIVector(x: 1, y: 1)] let greenCurve = [CIVector(x: 0, y: 0), CIVector(x: 0.247, y: 0.196), CIVector(x: 0.5, y: 0.5), CIVector(x: 1, y: 1)] let blueCurve = [CIVector(x: 0, y: 0), CIVector(x: 0.235, y: 0.184), CIVector(x: 0.466, y: 0.466), CIVector(x: 1, y: 1)] in colorCurvesFilter which I've found in Apple Docs: func colorCurves(inputImage: CIImage) -> CIImage { let colorCurvesEffect = CIFilter.colorCurves() colorCurvesEffect.inputImage = inputImage colorCurvesEffect.curvesDomain = CIVector(x: 0, y: 1) colorCurvesEffect.curvesData = Data( bytes: [Float32]([ 0.0,0.0,0.0, 0.8,0.8,0.8, 1.0,1.0,1.0 ]), count: 36) colorCurvesEffect.colorSpace = CGColorSpaceCreateDeviceRGB() return colorCurvesEffect.outputImage! }

How can I use my RGB Curve points: let redCurve = [CIVector(x: 0, y: 0), CIVector(x: 0.235, y: 0.152), CIVector(x: 0.5, y: 0.5), CIVector(x: 1, y: 1)] let greenCurve = [CIVector(x: 0, y: 0), CIVector(x: 0.247, y: 0.196), CIVector(x: 0.5, y: 0.5), CIVector(x: 1, y: 1)] let blueCurve = [CIVector(x: 0, y: 0), CIVector(x: 0.235, y: 0.184), CIVector(x: 0.466, y: 0.466), CIVector(x: 1, y: 1)] in colorCurvesFilter which I've found in Apple Docs: func colorCurves(inputImage: CIImage) -> CIImage { let colorCurvesEffect = CIFilter.colorCurves() colorCurvesEffect.inputImage = inputImage colorCurvesEffect.curvesDomain = CIVector(x: 0, y: 1) colorCurvesEffect.curvesData = Data( bytes: [Float32]([ 0.0,0.0,0.0, 0.8,0.8,0.8, 1.0,1.0,1.0 ]), count: 36) colorCurvesEffect.colorSpace = CGColorSpaceCreateDeviceRGB() return colorCurvesEffect.outputImage! }

I’m building a camera app using SwiftUI and UIKit (with UIViewControllerRepsrwsentable). My app already is able to capture photos, but I also want to implement the important feature - apply my custom image filter to the image for live preview in camera and when this image is saving to the photo library (like in the default Apple camera app with Photographic styles). My image filter must be pretty advanced because I’m a photographer and I trying to achieve the same colours as I have with my custom image preset in Lightroom. I want to control the image parameters such as basic (exposure, contrast, shadows, etc.), tone curves for each channel (Red, Green, Blue channels separately), HSL (for Red, Orange, Yellow, Green, Blue, Aqua, Purple and Magenta), apply colour grading and more. Currently I’m straggling with implementation of this. I tried to create a custom image filter using Metal (it works with saturation) but I’m not sure if it is the best approach. I need help and recommendations of how developers implement this complex thing in their apps (what technologies should I use and etc.)

I want to implement the ability to apply Lightroom Preset (.xmp file) to an image in my app, but am running into difficulties. How can I configure things like color grading, curve, etc. in Swift?

I’m using WeatherKit REST API since September and all worked well until now. Sometimes the currentWeather key doesn’t exist when I’m parsing JSON. Does anybody here has the same problem?

I want to use weather alert for my weather app but I don't understand how URL should look like. Can anyone help me?