How to scan B&W line art
Here's a method I have used to scan my comic line art since around 2005. I can't recall exactly where I learned this technique, but at the time I confirmed that it was standard practice by a couple of other professional comic artists.
It might seem excessive but it gets impressive results and despite what you may think, it produces file sizes smaller than jpegs at a third of the resolution. It also produces the most accurate and crisp line art you can imagine.
- Scan art work at 1200 DPI greyscale
- Open in photoshop (Crop, resize, transform how you want)
- Clean up artwork using you preferred method (for smudges, stray dot, inks spills, mistakes etc)
- eraser tool
- Change the colour mode: Image / Mode / Bitmap
- A context menu appears with options, chose
- Output 1200px per inch
- Method: 50% threshold
- File / Save as / TIF / LZW compression
Now you have a super hi resolution digital file of you artwork that you can use for printing. The file size is even more reasonable than a jpeg thanks to the LZW compression option. This method also works for colour pieces but requires some extra steps.
- Prepare you artwork as above
- Once saved, revert back to greyscale: Image / Mode / Greyscale
- Reduce image size: Image / Image Size / Resolution [change to] 300dpi
- Create a new layer/s for colour
- Put B&W line art layer to blending mode / multiply
- Colour artwork as best you see fit
- When done colouring, turn off all layers except colour
- Make a copy of the file (as not to overrwite your hi-res B&W file
- File / Save As / jpeg (or whatever works for you)
- Open up Adobe Illustraor (or similar software)
- Create a new file the final print size of you document
- Place the colour jpeg file
- Then place the B&W line art over that (they have the same dimensions, although one has a 300dpi resolution and the other 1200dpi)
- Save as a PDF (or whatever file you need)
This way you have the colour saved at a reasonable DPI (and file size) and the super hi res and crisp line art goes over the top. It might sound crazy but it results I impressive results with manageable file sizes.
I found this True Grit overview of using 1200DPI bitmapped Tifs useful, https://www.truegrittexturesupply.com/blogs/news/1200dpi-or-die