SunTzv/PDFilter ? reverse-engineered prompt

Build me a command line tool that can take a PDF and apply visual filters to it page by page, then save a new PDF with the changes. I want it to support a few easy presets like dark mode, sepia, grayscale, high contrast, and a stronger midnight style, plus a custom mode where I can tweak things like invert, brightness, and saturation myself.

It should process pages in parallel so big PDFs finish faster, and it should keep the pages looking sharp enough for reading or printing. By default it can use a sensible DPI, but let me raise it if I want better quality. Make the output file name automatic, like adding the preset name to the original file.

If you need to look up current docs or package details online, go ahead. I mostly want a simple tool that feels fast, works from the terminal, and makes PDFs easier on the eyes or better for printing.