I am trying to create a custom CGColorSpace in Swift on macOS but am not sure I really understand the concepts. I want to use a custom color space called Spot1 and if I extract the spot color from a PDF I get the following: "ColorSpace<Dictionary>" = { "Cs2<Array>" = ( Separation, Spot1, DeviceCMYK, { "BitsPerSample<Integer>" = 8; "Domain<Array>" = ( 0, 1 ); "Filter<Name>" = FlateDecode; "FunctionType<Integer>" = 0; "Length<Integer>" = 526; "Range<Array>" = ( 0, 1, 0, 1, 0, 1, 0, 1 ); "Size<Array>" = ( 1024 ); } ); }; How can I create this same color space using the CGColorSpace(propertyListPlist: CFPropertyList) API func createSpot1() -> CGColorSpace? { let dict0 : NSDictionary = [ "BitsPerSample": 8, "Domain" : [0,1], "Filter" : "FlateDecode", "FunctionType" : 0, "Length" : 526, "Range" : [0,1,0,1,0,1,0,1], "Size" : [1024]] let dict : NSDictionary = [ "Cs2" : ["Separation","Spot1", "DeviceCMYK", dict0] ] let space = CGColorSpace(propertyListPlist: dict as CFPropertyList) if space == nil { DebugLog("Spot1 color space is nil!") } return space }

For better memory usage when working with MTLTextures (editing + displaying in render passes, compute shaders, etc.) is it possible to save the texture to the app's Documents folder, and then use an UnsafeMutablePointer to access/modify the contents of the texture before displaying in a render pass? And would this be performant (i.e 60fps)? That way the texture won't be directly in memory all the time, but the contents can still be edited and displayed when needed.

I am trying to carefully process HDR pixel buffers (10-bit YCbCr buffers) from the camera. I have watched all WWDC videos on this topic but have some doubts expressed below. Q. What assumptions are safe to make about sample values in Metal Core Image Kernels? Are the sample values received in Metal Core Image kernel linear or gamma corrected? Or does that depend on workingColorSpace property, or the input image that is supplied (though imageByMatchingToColorSpace() API, etc.)? And what could be the max and min values of these samples in either case? I see that setting workingColorSpace to NSNull() in context creation options will guarantee receiving the samples as is and normalised to [0-1]. But then it's possible the values are non-linear gamma corrected, and extracting linear values would involve writing conversion functions in the shader. In short, how do you safely process HDR pixel buffers received from the camera (which are in YCrCr420_10bit, which I believe have gamma correction applied, so Y in YCbCr is actually Y'. Can AVFoundation team clarify this?) ?

I understand that by default, Core image uses extended linear sRGB as default working color space for executing kernels. This means that the color values received (or sampled from sampler) in the Metal Core Image kernel are linear values without gamma correction applied. But if we disable color management by setting let options:[CIContextOption:Any] = [CIContextOption.workingColorSpace:NSNull()]; do we receive color values as it exists in the input texture (which may have gamma correction already applied)? In other words, the color values received in the kernel are gamma corrected and we need to manually convert them to linear values in the Metal kernel if required?

I have set AVCaptureVideoDataOutput with 10-bit 420 YCbCr sample buffers. I use Core Image to process these pixel buffers for simple scaling/translation. var dstBounds = CGRect.zero dstBounds.size = dstImage.extent.size /* *srcImage is created from sample buffer received from Video Data Output */ _ciContext.render(dstImage, to: dstPixelBuffer!, bounds: dstImage.extent, colorSpace: srcImage.colorSpace ) I then set the color attachments to this dstPixelBuffer using set colorProfile in the app settings (BT.709 or BT.2020). switch colorProfile { case .BT709: CVBufferSetAttachment(dstPixelBuffer!, kCVImageBufferColorPrimariesKey, kCVImageBufferColorPrimaries_ITU_R_709_2, .shouldPropagate) CVBufferSetAttachment(dstPixelBuffer!, kCVImageBufferTransferFunctionKey, kCVImageBufferTransferFunction_ITU_R_709_2, .shouldPropagate) CVBufferSetAttachment(dstPixelBuffer!, kCVImageBufferYCbCrMatrixKey, kCVImageBufferYCbCrMatrix_ITU_R_709_2, .shouldPropagate) case .HLG2100: CVBufferSetAttachment(dstPixelBuffer!, kCVImageBufferColorPrimariesKey, kCVImageBufferColorPrimaries_ITU_R_2020, .shouldPropagate) CVBufferSetAttachment(dstPixelBuffer!, kCVImageBufferTransferFunctionKey, kCVImageBufferTransferFunction_ITU_R_2100_HLG, .shouldPropagate) CVBufferSetAttachment(dstPixelBuffer!, kCVImageBufferYCbCrMatrixKey, kCVImageBufferYCbCrMatrix_ITU_R_2020, .shouldPropagate) } These pixel buffers are then vended to AVAssetWriter whose videoSettings is set to recommendedSettings by VDO. But the output seems to be washed out completely, esp. for SDR (BT.709). What am I doing wrong?

I have two CIContexts configured with the following options: let options1:[CIContextOption:Any] = [CIContextOption.cacheIntermediates: false, CIContextOption.outputColorSpace: NSNull(), CIContextOption.workingColorSpace: NSNull()]; let options2:[CIContextOption:Any] = [CIContextOption.cacheIntermediates: false]; And an MTKView with CAMetalLayer configured with HDR output. metalLayer = self.layer as? CAMetalLayer metalLayer?.wantsExtendedDynamicRangeContent = true metalLayer.colorspace = CGColorSpace(name: CGColorSpace.itur_2100_HLG) colorPixelFormat = .bgr10a2Unorm The two context options produce different outputs when input is in BT.2020 pixel buffers. But I believe the outputs shouldn't be different. Because the first option simply disables color management. The second one performs intermediate buffer calculations in sRGB extended linear color space and then converts those buffers to BT.2020 color space in the output.

I have imported two metal files and defined two stitchable Metal Core Image kernels, one of them being CIColorKernel and other being CIKernel. As outlined in the WWDC video, I need to add a flag -framework CoreImage to other Metal Linker flags. Unfortunately, Xcode 15 puts a double quotes around this and generates an error metal: error: unknown argument: '-framework CoreImage'. So I built without this flag and it works for the first kernel that was added. The other kernel is never added to metal.defaultlib and fails to load. How do I get it working? class SobelEdgeFilterHDR: CIFilter { var inputImage: CIImage? var inputParam: Float = 0.0 static var kernel: CIKernel = { () -> CIKernel in let url = Bundle.main.url(forResource: "default", withExtension: "metallib")! let data = try! Data(contentsOf: url) let kernelNames = CIKernel.kernelNames(fromMetalLibraryData: data) NSLog("Kernels \(kernelNames)") return try! CIKernel(functionName: "sobelEdgeFilterHDR", fromMetalLibraryData: data) }() override var outputImage : CIImage? { guard let inputImage = inputImage else { return nil } return SobelEdgeFilterHDR.kernel.apply(extent: inputImage.extent, roiCallback: { (index, rect) in return rect }, arguments: [inputImage]) } }

I just noticed that +[CIPlugIn loadAllPlugIns] has been deprecated since 10.15 (OK, I'm a little slow), along with all the other CIPlugIn methods except for loadNonExecutablePlugIns. I don't see any documentation about what I'm supposed to do instead. What's the deal?

I am currently using CoreImage to process YCbCr422/420 10-bit pixel buffers but it is lacking performance at high frame rates so I decided to switch to Metal. But with Metal I am getting even worse performance. I am loading both the Luma (Y) and Chroma (CbCr) textures in 16-bit format as follows: let pixelFormatY = MTLPixelFormat.r16Unorm let pixelFormatUV = MTLPixelFormat.rg16Unorm renderPassDescriptorY!.colorAttachments[0].texture = texture; renderPassDescriptorY!.colorAttachments[0].loadAction = .clear; renderPassDescriptorY!.colorAttachments[0].clearColor = MTLClearColor(red: 0.0, green: 0.0, blue: 0.0, alpha: 1.0) renderPassDescriptorY!.colorAttachments[0].storeAction = .store; renderPassDescriptorCbCr!.colorAttachments[0].texture = texture; renderPassDescriptorCbCr!.colorAttachments[0].loadAction = .clear; renderPassDescriptorCbCr!.colorAttachments[0].clearColor = MTLClearColor(red: 0.0, green: 0.0, blue: 0.0, alpha: 1.0) renderPassDescriptorCbCr!.colorAttachments[0].storeAction = .store; // Vertices and texture coordinates for Metal shader let vertices:[AAPLVertex] = [AAPLVertex(position: vector_float2(-1.0, -1.0), texCoord: vector_float2( 0.0 , 1.0)), AAPLVertex(position: vector_float2(1.0, -1.0), texCoord: vector_float2( 1.0, 1.0)), AAPLVertex(position: vector_float2(-1.0, 1.0), texCoord: vector_float2( 0.0, 0.0)), AAPLVertex(position: vector_float2(1.0, 1.0), texCoord: vector_float2( 1.0, 0.0)) ] let commandBuffer = commandQueue!.makeCommandBuffer() if let commandBuffer = commandBuffer { let renderEncoderY = commandBuffer.makeRenderCommandEncoder(descriptor: renderPassDescriptorY!) renderEncoderY?.setRenderPipelineState(pipelineStateY!) renderEncoderY?.setVertexBytes(vertices, length: vertices.count * MemoryLayout<AAPLVertex>.stride, index: 0) renderEncoderY?.setFragmentTexture(CVMetalTextureGetTexture(lumaTexture!), index: 0) renderEncoderY?.setViewport(MTLViewport(originX: 0, originY: 0, width: Double(dstWidthY), height: Double(dstHeightY), znear: 0, zfar: 1)) renderEncoderY?.drawPrimitives(type: .triangleStrip, vertexStart: 0, vertexCount: 4, instanceCount: 1) renderEncoderY?.endEncoding() let renderEncoderCbCr = commandBuffer.makeRenderCommandEncoder(descriptor: renderPassDescriptorCbCr!) renderEncoderCbCr?.setRenderPipelineState(pipelineStateCbCr!) renderEncoderCbCr?.setVertexBytes(vertices, length: vertices.count * MemoryLayout<AAPLVertex>.stride, index: 0) renderEncoderCbCr?.setFragmentTexture(CVMetalTextureGetTexture(chromaTexture!), index: 0) renderEncoderCbCr?.setViewport(MTLViewport(originX: 0, originY: 0, width: Double(dstWidthUV), height: Double(dstHeightUV), znear: 0, zfar: 1)) renderEncoderCbCr?.drawPrimitives(type: .triangleStrip, vertexStart: 0, vertexCount: 4, instanceCount: 1) renderEncoderCbCr?.endEncoding() commandBuffer.commit() } And here is shader code: vertex MappedVertex vertexShaderYCbCrPassthru ( constant Vertex *vertices [[ buffer(0) ]], unsigned int vertexId [[vertex_id]] ) { MappedVertex out; Vertex v = vertices[vertexId]; out.renderedCoordinate = float4(v.position, 0.0, 1.0); out.textureCoordinate = v.texCoord; return out; } fragment half fragmentShaderYPassthru ( MappedVertex in [[ stage_in ]], texture2d<float, access::sample> textureY [[ texture(0) ]] ) { constexpr sampler s(s_address::clamp_to_edge, t_address::clamp_to_edge, min_filter::linear, mag_filter::linear); float Y = float(textureY.sample(s, in.textureCoordinate).r); return half(Y); } fragment half2 fragmentShaderCbCrPassthru ( MappedVertex in [[ stage_in ]], texture2d<float, access::sample> textureCbCr [[ texture(0) ]] ) { constexpr sampler s(s_address::clamp_to_edge, t_address::clamp_to_edge, min_filter::linear, mag_filter::linear); float2 CbCr = float2(textureCbCr.sample(s, in.textureCoordinate).rg); return half2(CbCr); } Is there anything fundamentally wrong in the code that makes it slow?

I have written and used the code to get the colors from CGImage and it worked fine up to iOS16. However, when I use the same code in iOS17, Red and Blue out of RGB are reversed. Is this a temporary bug in the OS and will it be fixed in the future? Or has the specification changed and will it remain this way after iOS17? Here is my code: let pixelDataByteSize = 4 guard let cfData = image.cgImage?.dataProvider?.data else { return } let pointer:UnsafePointer = CFDataGetBytePtr(cfData) let scale = UIScreen.main.nativeScale let address = ( Int(image.size.width * scale) * Int(image.size.height * scale / 2) + Int(image.size.width * scale / 2) ) * pixelDataByteSize let r = CGFloat(pointer[address]) / 255 let g = CGFloat(pointer[address+1]) / 255 let b = CGFloat(pointer[address+2]) / 255

I am trying to use a CIColorKernel or CIBlendKernel with sampler arguments but the program crashes. Here is my shader code which compiles successfully. extern "C" float4 wipeLinear(coreimage::sampler t1, coreimage::sampler t2, float time) { float2 coord1 = t1.coord(); float2 coord2 = t2.coord(); float4 innerRect = t2.extent(); float minX = innerRect.x + time*innerRect.z; float minY = innerRect.y + time*innerRect.w; float cropWidth = (1 - time) * innerRect.w; float cropHeight = (1 - time) * innerRect.z; float4 s1 = t1.sample(coord1); float4 s2 = t2.sample(coord2); if ( coord1.x > minX && coord1.x < minX + cropWidth && coord1.y > minY && coord1.y <= minY + cropHeight) { return s1; } else { return s2; } } And it crashes on initialization. class CIWipeRenderer: CIFilter { var backgroundImage:CIImage? var foregroundImage:CIImage? var inputTime: Float = 0.0 static var kernel:CIColorKernel = { () -> CIColorKernel in let url = Bundle.main.url(forResource: "AppCIKernels", withExtension: "ci.metallib")! let data = try! Data(contentsOf: url) return try! CIColorKernel(functionName: "wipeLinear", fromMetalLibraryData: data) //Crashes here!!!! }() override var outputImage: CIImage? { guard let backgroundImage = backgroundImage else { return nil } guard let foregroundImage = foregroundImage else { return nil } return CIWipeRenderer.kernel.apply(extent: backgroundImage.extent, arguments: [backgroundImage, foregroundImage, inputTime]) } } It crashes in the try line with the following error: Fatal error: 'try!' expression unexpectedly raised an error: Foundation._GenericObjCError.nilError If I replace the kernel code with the following, it works like a charm: extern "C" float4 wipeLinear(coreimage::sample_t s1, coreimage::sample_t s2, float time) { return mix(s1, s2, time); }

How can I take the contents (i.e. the stroke and fill) of a CAShapeLayer and draw it into an MTLTexture, which can then be displayed with a normal vertex/fragment shader?

I am processing CVPixelBuffers received from camera using both Metal and CoreImage, and comparing the performance. The only processing that is done is taking a source pixel buffer and applying crop & affine transforms, and saving the result to another pixel buffer. What I do notice is CPU usage is as high a 50% when using CoreImage and only 20% when using Metal. The profiler shows most of the time spent is in CIContext render: let cropRect = AVMakeRect(aspectRatio: CGSize(width: dstWidth, height: dstHeight), insideRect: srcImage.extent) var dstImage = srcImage.cropped(to: cropRect) let translationTransform = CGAffineTransform(translationX: -cropRect.minX, y: -cropRect.minY) var transform = CGAffineTransform.identity transform = transform.concatenating(CGAffineTransform(translationX: -(dstImage.extent.origin.x + dstImage.extent.width/2), y: -(dstImage.extent.origin.y + dstImage.extent.height/2))) transform = transform.concatenating(translationTransform) transform = transform.concatenating(CGAffineTransform(translationX: (dstImage.extent.origin.x + dstImage.extent.width/2), y: (dstImage.extent.origin.y + dstImage.extent.height/2))) dstImage = dstImage.transformed(by: translationTransform) let scale = max(dstWidth/(dstImage.extent.width), CGFloat(dstHeight/dstImage.extent.height)) let scalingTransform = CGAffineTransform(scaleX: scale, y: scale) transform = CGAffineTransform.identity transform = transform.concatenating(scalingTransform) dstImage = dstImage.transformed(by: transform) if flipVertical { dstImage = dstImage.transformed(by: CGAffineTransform(scaleX: 1, y: -1)) dstImage = dstImage.transformed(by: CGAffineTransform(translationX: 0, y: dstImage.extent.size.height)) } if flipHorizontal { dstImage = dstImage.transformed(by: CGAffineTransform(scaleX: -1, y: 1)) dstImage = dstImage.transformed(by: CGAffineTransform(translationX: dstImage.extent.size.width, y: 0)) } var dstBounds = CGRect.zero dstBounds.size = dstImage.extent.size _ciContext.render(dstImage, to: dstPixelBuffer!, bounds: dstImage.extent, colorSpace: srcImage.colorSpace ) Here is how CIContext was created: _ciContext = CIContext(mtlDevice: MTLCreateSystemDefaultDevice()!, options: [CIContextOption.cacheIntermediates: false]) I want to know if I am doing anything wrong and what could be done to lower CPU usage in CoreImage?

macOS 14 Sonoma cifilter issue (Designed for iPad) I just updated my M1 Mac to MacOS 14 Sonoma. I ran the iOS/iPadOS app built in Xcode 15.0 on a Mac whose OS was updated using Testflight. (My app is Designed for iPad and is set to run on macOS.) When UIImage is processed using cifilter, the generated image may be grayed out. The same code does not occur on iOS and iPadOS. In other words, it does not occur on iPhone and iPad iOS/iPadOS 17. Has anyone experienced a similar issue? And I would like to know the solution ASAP. I am distributing the app as Designed for iPad. Every year, when Mac OS is updated, an issue arises. So, I am considering not allowing Vision Pro to run the current iOS/iPadOS app.

Hello All, I am trying to compress PNG image by applying PNG Filters like(Sub, Up, Average, Paeth), I am applying filers using property kCGImagePropertyPNGCompressionFilter but there is no change seen in resultant images after trying any of the filter. What is the issue here can someone help me with this. Do I have compress image data after applying filter? If yes how to do that? Here is my source code CGImageDestinationRef outImageDestRef = NULL; long keyCounter = kzero; CFStringRef dstImageFormatStrRef = NULL; CFMutableDataRef destDataRef = CFDataCreateMutable(kCFAllocatorDefault,0); Handle srcHndl = //source image handle; ImageTypes srcImageType = //'JPEG', 'PNGf, etct; CGImageRef inImageRef = CreateCGImageFromHandle(srcHndl,srcImageType); if(inImageRef) { CFTypeRef keys[4] = {nil}; CFTypeRef values[4] = {nil}; dstImageFormatStrRef = CFSTR("public.png"); long png_filter = IMAGEIO_PNG_FILTER_SUB; //IMAGEIO_PNG_FILTER_SUB, IMAGEIO_PNG_FILTER_UP, IMAGEIO_PNG_FILTER_AVG, IMAGEIO_PNG_FILTER_PAETH .. it is one of this at a time keys[keyCounter] = kCGImagePropertyPNGCompressionFilter; values[keyCounter] = CFNumberCreate(NULL,kCFNumberLongType,&png_filter); keyCounter++; outImageDestRef = CGImageDestinationCreateWithData(destDataRef, dstImageFormatStrRef, 1, NULL); if(outImageDestRef) { // keys[keyCounter] = kCGImagePropertyDPIWidth; // values[keyCounter] = CFNumberCreate(NULL,kCFNumberLongType,&Resolution); // keyCounter++; // // keys[keyCounter] = kCGImagePropertyDPIHeight; // values[keyCounter] = CFNumberCreate(NULL,kCFNumberLongType,&Resolution); // keyCounter++; CFDictionaryRef options = CFDictionaryCreate(NULL,keys,values,keyCounter,&kCFTypeDictionaryKeyCallBacks,&kCFTypeDictionaryValueCallBacks); CGImageDestinationAddImage(outImageDestRef,inImageRef, options); CFRelease(options); status = CGImageDestinationFinalize(outImageDestRef); if(status == true) { UInt8 *destImagePtr = CFDataGetMutableBytePtr(destDataRef); destSize = CFDataGetLength(destDataRef); //using destImagePtr after this ... } CFRelease(outImageDestRef); } for(long cnt = kzero; cnt < keyCounter; cnt++) if(values[cnt]) CFRelease(values[cnt]); if(inImageRef) CGImageRelease(inImageRef); }

Hello! After recent talk on the WWDC2023 about HDR support and finding this documentation page on Applying Apple HDR effect on photos, I became very interested in the HDR Gain Map format. From documentation page it is clear how we can restore original HDR from SDR and Gain Map representation, but my question is - how from HDR we can convert back to the SDR + Gain Map representation? As I understand right know, conversion from HDR to SDR + Gain Map includes two steps: Tone mapping of HDR for getting correct SDR When we have both HDR and SDR, from equation in the documentation page we can calculate Gain Map Am I correct? If so, what tone mapping algorithm for HDR -> SDR conversion is used right know? Can't find any information about this in the internet:( Would be very grateful for your response!

HEIF Decompression Crash on iOS 17.