如何在更小的屏幕上不需要去拜耳的情况下采样原始图像?

I have a question about reducing the overall size of a RAW image without going into the linear space. The reason is, I want to try to edit a very large megapixel image (60+ megapixels), but don't need the full image while editing on something like an iPad or iPhone screen. Once the edit is done, I do want to save out the original. The speed for saving isn't a concern, it's the editing done on the "working" image that I'm previewing the edits on.I have a question about reducing the overall si