Using GPUImage2 with CIFilters

Question

I'm using GPUImage along with CIFilter to process an image. However, this is proving to be extremely memory intensive, and I'm trying to find a better solution. I'm mainly using CIFilter, but GPUImage2 provides an AdaptiveThreshold filter that CIFilter doesn't supply. As a result, I must use both in my project. Is there a way to transfer the outputImage of CIFilter to GPUImage2 without too much overhead? Or is there a way to port a GPUImage2 filter to CIFilter or vice versa. Here's some example code I'm using now:

    let openGLContext = EAGLContext(api: .openGLES2)
    let context = CIContext(eaglContext: openGLContext!)

    guard let cgFilteredImage = context.createCGImage(noiseReductionOutput, from: noiseReductionOutput.extent) else {
        completionHandler(nil)
        return
    }

    let correctlyRotatedImage = UIImage(cgImage: cgFilteredImage, scale: imageToProcess.scale, orientation: imageToProcess.imageOrientation)

    //
    // GPUImage
    //

    let orientation = ImageOrientation.orientation(for: correctlyRotatedImage.imageOrientation)

    let pictureInput = PictureInput(image: correctlyRotatedImage, orientation: orientation)
    let processedImage = PictureOutput()

    pictureInput --> adaptiveThreshold --> processedImage

    processedImage.imageAvailableCallback = {
        image in
        completionHandler(image)
    }

    pictureInput.processImage(synchronously: true)

Additionally, I'm trying to use CIFilter in the most efficient way possible by chaining filters like this:

    let filter = CIFilter(name: "Filter_Name_Here")!
    guard let filterOutput = filter.outputImage else {
        completionHandler(nil)
        return
    }

    let secondFilter = CIFilter(name: "Filter_Name_Here")!
    secondFilter.setValuesForKeys([kCIInputImageKey: filterOutput])