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Performant alternative to scaling a CIImage / PixelBuffer
Hey, I’m building a camera app where I am applying real time effects to the view finder. One of those effects is a variable blur, so to improve performance I am scaling down the input image using CIFilter.lanczosScaleTransform(). This works fine and runs at 30FPS, but when running the metal profiler I can see that the scaling transforms use a lot of GPU time, almost as much as the variable blur. Is there a more efficient way to do this? The simplified chain is like this: Scale down viewFinder CVPixelBuffer (CIFilter.lanczosScaleTransform) Scale up depthMap CVPixelBuffer to match viewFinder size (CIFilter.lanczosScaleTransform) Create CIImages from both CVPixelBuffers Apply VariableDepthBlur (CIFilter.maskedVariableBlur) Scale up final image to metal view size (CIFilter.lanczosScaleTransform) Render CIImage to a MTKView using CIRenderDestination From some research, I wonder if scaling the CVPixelBuffer using the accelerate framework would be faster? Also, Instead of scaling the final image, perhaps I could offload this to the metal view? Any pointers greatly appreciated!
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1.1k
Jul ’24
How to access HDRGainMap from AVCapturePhoto
Hey, I'm building a camera app and I want to use the captured HDRGainMap along side the photo to do some processing with a CIFilter chain. How can this be done? I can't find any documentation any where on this, only on how to access the HDRGainMap from an existing HEIC file, which I have done successfully. For this I'm doing something like the following: let gainmap = CGImageSourceCopyAuxiliaryDataInfoAtIndex(source, 0, kCGImageAuxiliaryDataTypeHDRGainMap) let gainDict = NSDictionary(dictionary: gainmap) let gainData = gainDict[kCGImageAuxiliaryDataInfoData] as? Data let gainDescription = gainDict[kCGImageAuxiliaryDataInfoDataDescription] let gainMeta = gainDict[kCGImageAuxiliaryDataInfoMetadata] However I'm not sure what the approach is with a AVCapturePhoto output from a AVCaptureDevice. Thanks!
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777
Jan ’25
Photos are captured with incorrect exposure bias in specific scenarios on iPhone 17 Pro
Hey, There seems to be an inconsistency when capturing a photo using QualityPrioritization.Quality on the iPhone 17 Pro Main wide Lens. If you zoom above "2x" the output image always has "-2.0ev" bias in the meta data and looks underexposued. This does not happen at zoom levels above 2, or if you set the QualityPrioritization to .Balanced. See below: with .Quality with .Balanced This does not happen on the other lenses. I'm using a simple set up and it is consistent across JPEG and ProRAW capture. I have a demo project if that is useful. Thanks, Alex
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478
Dec ’25