How to efficiently cascade CIFilters-CodePudding

Currently I'm cascading CIFilters like this:

    let filterA = CIFilter(...)
    let filterB = CIFilter(...)
    let filterC = CIFilter(...)

    var outputImage = CIImage(data: myInputData, options: [.applyOrientationProperty : true])

    filterA.setValue(outputImage, forKey: kCIInputImageKey)
    var outputImage = filterA.outputImage

    filterB.setValue(outputImage, forKey: kCIInputImageKey)
    var outputImage = filterB.outputImage

    filterC.setValue(outputImage, forKey: kCIInputImageKey)
    var outputImage = filterC.outputImage

    return render(ouputImage)

Is using one var outputImage in some way inefficient? Or in general words, what is the most performance efficient way of cascading CIFilters?

CodePudding user response：

Basically that’s fine. Whether you use those extra variables or not really doesn’t matter as Core Image only computes the effects once the image is rendered.

Personally I wouldn’t recommend reusing the same variable for each image, might get confusing as to which image is used where. Instead I’d directly pass the property from each filter:

filterA.setvalue(inputImage, forKey: kCIInputImageKey)
filterB.setValue(filterA.outputImage, forKey: kCIInputImageKey)
filterC.setValue(filterB.outputImage, forKey: kCIInputImageKey)

return render(filterC.outputImage)

The performance will be exactly the same.