How to you make hand drawn patterns look nice on a computer?

You might be scanning at a resolution that is too low? You should use at least 300DPI.

 

If your printer has a dedicated program with settings (e.g. ScanGear for Canon) it might offer different scanning resolutions.
It could be that you're ending up with an image that is a bit small, and when you place it in a PDF it gets blown up/blurry and pixellated.
It's just a guess though.

 

What kind of scanner are you using? Some of them (cough hp cough) will auto "fix" any images you scan, which seems to just mean upping the contrast and brightness of everything, making lines faint and messing with color balance. It seems to be less of an issue when scanning directly to pdf as opposed to an image file (ie png, jpeg, tiff), but it's been a problem for me that I have to keep our old dead epson printer just for its scanning abilities because the hp one kills any images i scan, regardless of the settings i use. If you plan on scanning a lot of images, you may want to invest in a dedicated scanner that will let you tweak the settings more.

 

So, I'm a bit old school, but I do it like this:
Make a clean copy of the pattern using a pencil. Then I ink the lines, let dry and erase the pencil. Now I have black, clean lines and minimum dirt or smudges.
Then I scan and save as a monocrome bitmap. This gets rid of anything that isn't black. I enlarge the image and erase any stray specks of black and clean up the lines if I have to. I do all this in MS paint and it actually works fine.
Once I am happy I convert it to the file format I want.

 

Lomi has a video where they digitize a pattern in this video starting at about the 9 minute mark. She uses photoshop, but any application with a vector lines and nodes can work (example: Inkscape is an open source free program).

 

If you want it to look clear right as you scan it, I'd try going over the pencil lines with dark pen or even thin marker. That's probably what I'd do just for ease. Scanners have an easier time picking up the jet black than the pencil grays.

If you'd rather make it clear on the computer, try a program like Photoshop or Clip Studio Paint- or a free program like GIMP. These programs allow you to draw over your picture/pattern on a separate layer, using your mouse or trackpad (assuming you don't own a drawing tablet). Then you can delete the original drawing layer and be left with just the nice-looking lines. The exact method of doing all this will depend on which program you ultimately choose.

 

I am not sure if you found a solution, but I have used a fine tip Sharpie to trace and scan. It turns out perfectly and very readable!

 

Inkscape is a vector program, so it's not really what you're looking for here. If you want something free but with a terrible interface, GIMP is your answer--if you're willing to spend a little more, Affinity Photo goes on sale fairly frequently. (But even full price it's only $70.) You do likely want to use pen, but also your scanner was definitely "fixing" the image for you and throwing off the contrast. The other problem with pencil artwork is that it's slightly shiny, and scanners shine light at your image, which can cause you even more issues. (Any scanner nowadays should be able to scan in pencil anyway, but still.) Your scanner should have a preview where you can see what you're going to get, and you can fuss with things there usually.

After that, you're going to follow the same steps for cleaning up any linework. Here's another video that shows you how to do that using GIMP:



There's actually many ways to approach this particular task, but this one is pretty simple.