How can HDR be added to Metal?

To add HDR to Metal, you can follow these steps as outlined in the session "Use HDR for dynamic image experiences in your app" from WWDC 2024:

1. Set Up MTKView for Extended Range Content:

   • First, configure your MTKView to support extended range content. This is essential for displaying HDR images correctly.

2. Apply Filters to Create an Edited CIImage:

   • Use Core Image filters to process your HDR image. This might involve applying a tonemap headroom filter if you are working with adaptive HDR images.

3. Display the Result in MTKView:

   • Finally, render the processed CIImage in your MTKView.

Here is a brief code example to illustrate these steps:

// Set up MTKView for extended range content
mtkView.colorPixelFormat = .bgra10_xr_srgb

// Create a CIImage from your HDR source
let ciImage = CIImage(contentsOf: hdrImageURL, options: [.expandHDR: true])

// Apply necessary filters (e.g., tonemap headroom filter)
let tonemapFilter = CIFilter(name: "CITonemapHeadroom")
tonemapFilter?.setValue(ciImage, forKey: kCIInputImageKey)
let outputImage = tonemapFilter?.outputImage

// Render the CIImage in MTKView
let context = CIContext(mtlDevice: mtkView.device!)
context.render(outputImage!, to: mtkView.currentDrawable!.texture, commandBuffer: nil, bounds: outputImage!.extent, colorSpace: CGColorSpaceCreateDeviceRGB())

For more detailed information, you can refer to the chapter on Display tone mapping in the session "Use HDR for dynamic image experiences in your app".

Session Chapter Markers

• Introduction
• HDR concepts and technologies
• Adaptive HDR
• Read HDR images
• Edit strategies
• Display tone mapping
• Saving images