Though a non-trival task, it is possible to generate AVDepthData and add it to your own image.
- create a depth/disparity dictionary like that documented in
CGImageSource.h CGImageSourceCopyAuxiliaryDataInfoAtIndex- however, following are more details:
Key kCGImageAuxiliaryDataInfoData - (CFDataRef) - the depth data
Contains just a binary pixel buffer. As in it’s the data you pull out of a pixel buffer by reading the pointer in CVPixelBufferLockBaseAddress. You create the CVPixelBuffer with a format of one of the supported types:
- kCVPixelFormatType_DisparityFloat16 = 'hdis', /* IEEE754-2008 binary16 (half float), describing the normalized shift when comparing two images. Units are 1/meters: ( pixelShift / (pixelFocalLength * baselineInMeters) ) */
- kCVPixelFormatType_DisparityFloat32 = 'fdis', /* IEEE754-2008 binary32 float, describing the normalized shift when comparing two images. Units are 1/meters: ( pixelShift / (pixelFocalLength * baselineInMeters) ) */
- kCVPixelFormatType_DepthFloat16 = 'hdep', /* IEEE754-2008 binary16 (half float), describing the depth (distance to an object) in meters */
- kCVPixelFormatType_DepthFloat32 = 'fdep', /* IEEE754-2008 binary32 float, describing the depth (distance to an object) in meters */
To turn an arbitrary grayscale image into a fake depth buffer, you’ll need to per-pixel convert whatever your grayscale pixel values are (0=black to 1=white, zNear to zFar, etc) to either meters or 1/meters depending on your target format. And get them into the right floating-point format, depending on where you’re getting them from.
Key kCGImageAuxiliaryDataInfoDataDescription - (CFDictionary) - the depth data description
Tells you how to interpret that buffer for one we give you, or tells us how to interpret a buffer you give us:
- kCGImagePropertyPixelFormat is one of the CoreVideo/CVPixelBuffer.h depth/disparity formats
- kCGImagePropertyWidth/Height are the pixel dimensions
- kCGImagePropertyBytesPerRow is correctly what it says on the tin
Key kCGImageAuxiliaryDataInfoMetadata - (CGImageMetadataRef) - metadata
This value is optional.
- Create AVDepthData with init(fromDictionaryRepresentation: [AnyHashable : Any]) passing the dictionary created above.
Create an image using ImageI/O:
// create the image destination (not shown)
// add an image to the destination
CGImageDestinationAddImage(cgImageDestination, renderedCGImage, attachments)
// Use AVDepthData to get auxiliary data dictionary
var auxDataType :NSString?
let auxData = depthData.dictionaryRepresentation(forAuxiliaryDataType: &auxDataType)
// Add auxiliary data to image destination
CGImageDestinationAddAuxiliaryDataInfo(cgImageDestination, auxDataType!, auxData! as CFDictionary)
if CGImageDestinationFinalize(cgImageDestination) {
return data as Data
}
