QuantizerProposal.cs

public interface IQuantizer
{
    // Remove:
    // IFrameQuantizer<TPixel> CreateFrameQuantizer<TPixel>(Configuration configuration, QuantizerOptions options)
    //        where TPixel : unmanaged, IPixel<TPixel>;

    // Add:
    IQuantizer<TPixel> CreatePixelSpecificQuantizer<TPixel>(Configuration configuration, QuantizerOptions options)
            where TPixel : unmanaged, IPixel<TPixel>;
}

// Renamed from FrameQuantizer<TPixel>
public interface IQuantizer<TPixel> : IDisposable
    where TPixel : unmanaged, IPixel<TPixel>
{
    // Remove:
    // void BuildPalette(ImageFrame<TPixel> source, Rectangle bounds);

    // Add:
    void CollectPaletteColors(BufferArea<TPixel> pixels); // can be invoked multiple times for different frames
}