This Python package provides lossless conversion of raster images to PDF. You
should use img2pdf if your priorities are (in this order):

1. "always lossless": The image embedded in the PDF will always have the exact
   same color information for every pixel as the input.

2. "small": If possible, the difference in filesize between the input image and
   the output PDF will only be the overhead of the PDF container itself.

3. "fast": If possible, the input image is just pasted into the PDF document
   as-is without any CPU hungry re-encoding of the pixel data.

Conventional conversion software (like ImageMagick) would either:

1. Not be lossless because lossy re-encoding to JPEG.
2. Not be small because using wasteful flate encoding of raw pixel data.
3. Not be fast because input data gets re-encoded.

Another advantage of not having to re-encode the input (in most common
situations) is, that img2pdf is able to handle much larger input than other
software, because the raw pixel data never has to be loaded into memory.