I have a Fujitsu fi-5015C

It is a workhorse. I've had it for 6+ years and not one problem with it. 

It came highly recommended to me ... I am so happy with it. 

If I'm mobile I use scanner on my iphone: genius scan.

I love my HP - works like a charm and has for years! 

Most of the HP printers also scan. Many options.

I have an HP and love it

We have Canons in the KW offices, and HP in the WMS offices

Can't you import the JPG into something like the Microsoft Picture Manager and increase the contrast?  

Your first concern must be the size of the documents. Will you need a wide document device able to do 17 inches?  This will reduce your choices by 80%

Second consideration, it the poor quality independent of document feed or off the glass? Have you performed maintenance on the printer (clean jets and align print heads)? IS printer at end of useful life? 

4800 x 1200 is the dpi of nearly all business grade 3 in 1 printers.  Replacing the printer could be the solution if the existing printer if ready to croak or maintenance does not fix.

I recommend the Epsom eco-tank ET-4750 (standard) or ET-16500

We just switched from an epson to an HP, because the feeder stopped working on the Epson. Sometimes scanning it in color works better than scanning in black and whiote I have found.

Parked and watching the responses.

I am happy with the HP8600

I've used a Xerox scanner for many years.

I also use a Fujitsu and I love it I am about to buy another...

Maybe you just need to choose a different way to scan; black and white, grayscale, automatic or color. That should help.

I use an HP 8600 printer/scanner/copier with ability to lighten/darken

Most scanners, or scanning apps have an adjustment for lighter and darker. May want to look into this...

There is usually software where that is easily done. Every scanner I've ever used has had that feature. You can also darken it also with any photo software.

I like my Brother device.  There are probably settings in the scanning program for the printer that will let you manipulate it.

Often quick and easy to huddle down over the top of a plat or house plan with the Sony A7riii and snap snap then off to photo shop. Crystal clear and no wrestling with the scanner designed for small applications.

We use our HP printer and it does a great job.  A

Great question and asnwers. Good luck. 

Good answers are here. I hope you find the best one. 

I may have a workaround for you as a possible feel free to get in direct contact with me... if you haven't already found a solution :-Dave

Cathy Hertler my scanner has been out of production for YEARS! works fine for me.

I have bought many HP printers with scanning capabilities and have been very happy.

I use a HP product and have for years with little issues

Good luck.

  Can you use PhotoShop or Irfanview to adjust the scanned images?

  If not, consider an HP scanner.

Fujitsu ScanSnap

Cathy Hertler - nice to see you from Billerica, MA.

Microsoft LENS is a free scanner on your smartphone. Pretty sleek.

Physical scanners - I use one from office. I had one from Brother a while ago - pretty good one.

I use an HP all in one and it does a fine job for around $200. It is going on it's 4th year.

Costco has a HP scanner/printer can't be beat for price, quality & warranty

Cathy Hertler I use a scanning program called VueScan. It has several options.

I'll check back to see more answers....

I currently use an Epson, but am open to suggestions.