CODEWITHSUNDEEP
ioscore-imagemetalkitmtkviewcametallayer
Deepak Sharma
Deepak Sharma

Reputation: 6477

CIContext workingColorSpace for MTKView

I have the following two contexts:

 private lazy var firstContext: CIContext  = {
    let options:[CIContextOption:Any] = [CIContextOption.cacheIntermediates: false];
    
    return CIContext(mtlDevice: self.device!, options: options)
}()

 private lazy var secondContext: CIContext  = {
    let options:[CIContextOption:Any] = [CIContextOption.cacheIntermediates: false, CIContextOption.outputColorSpace: NSNull(), CIContextOption.workingColorSpace: NSNull()];
    
    return CIContext(mtlDevice: self.device!, options: options)
}()

 public var useFirstContext = true

private var context: CIContext {

    return useFirstContext ? firstContext : secondContext
}

And my MTKView is configured as follows:

    metalLayer = self.layer as? CAMetalLayer
    
    metalLayer?.wantsExtendedDynamicRangeContent = true
    metalLayer.colorspace = CGColorSpace(name: CGColorSpace.itur_2100_HLG)
    
    colorPixelFormat = .bgr10a2Unorm

When I render incoming pixel buffers using ciContext, I see different outputs on MTKView with the two contexts. There is no filter chain configured, except for rescaling and transforming CIImage. Why is the output different with the two contexts when incoming buffers are in the same color space? Here is the drawing code:

 func drawCIImage(_ ciImage:CIImage?) {
    guard let image = ciImage,
        let currentDrawable = currentDrawable,
        let commandBuffer = commandQueue?.makeCommandBuffer()
        else {
            return
    }

    let drawableSize = self.drawableSize
    
    let scaleX = drawableSize.width / image.extent.width
    let scaleY = drawableSize.height / image.extent.height
    let scaledImage = image.transformed(by: CGAffineTransform(scaleX: scaleX, y: scaleY))
    let filteredImage = scaledImage
    
   
    let destination = CIRenderDestination(width: Int(drawableSize.width),
                                          height: Int(drawableSize.height),
                                          pixelFormat: self.colorPixelFormat,
                                          commandBuffer: commandBuffer,
                                          mtlTextureProvider: { () -> MTLTexture in
                                             return currentDrawable.texture
    })
    
    _ = try? context.startTask(toRender: filteredImage, to: destination)
    
    commandBuffer.present(currentDrawable)
    commandBuffer.commit()
}

Upvotes: 0

Views: 68

Answers (0)

Related Questions