Color inversion in excalidraw embedded images

So as a student, I often times find myself having to solve worksheets. I use excalidraw for that, which works great, except in the dark mode: most worksheet pdfs, pngs and jpgs are white with black text on them. so in the dark mode, when the pen is producing white “ink”, the ink isnt visible on the white worksheets. this is why i would like to have my colors always inverted for imported pdfs, imgs, etc. how do i do that?