A very simple set of instructions to get the Brother DCP-L2550DW working with CentOS 7.4 over the network.
https://www.amazon.ca/Brother-DCPL2550DW-Wireless-Monochrome-Printer/dp/B0764P8F5J (246.98 @ Jan 19 2023)
I’m assuming the printer/scanner combo has already been set up and given an ip address. I am also assuming that everything has been confirmed to be working over the network with a Windows machine.
The first step is to install the sane-backends if you haven’t already. This will give us the scanimage utility.
yum install sane-backends
Once we have this installed, we can now install the Brother printer drivers.
Specifically we want just the scanner driver:
This will let you download an rpm that we can then install:
yum install brscan4-0.4.11-1.x86_64.rpm
Now we need to configure the driver:
brsaneconfig4 -a name=Brother_DCP-L2550DW model=DCP-L2550DW ip=192.168.7.203
Now we can update /etc/sane.d/dll.conf and add brother4 to the list.
At this point we should be able to run
root@andromeda /h/n/bp# scanimage -L device `brother4:net1;dev0' is a Brother Brother_DCP-L2550DW DCP-L2550DW
Now load up a document and scan it!
scanimage --format tiff -d "brother4:net1;dev0" > image.tiff
This should have created a tiff image that we can do whatever we want with it.
convert image.tiff image.jpg convert image.jpg image.pdf
Convert comes from the ImageMagick set of utilities that can be installed:
yum install ImageMagick
Voila! We can now scan images to pdf programmatically from linux using scanimage and a Brother printer.
As always arch has the most helpful wiki:
You can get the specific options for the Brother printer by doing:
scanimage -h -d 'brother4:net1;dev0'
Options specific to devicebrother4:net1;dev0’:
–mode Black & White|Gray[Error Diffusion]|True Gray|24bit Color[Fast] [24bit Color[Fast]]
Select the scan mode
–resolution 100|150|200|300|400|600|1200|2400|4800|9600dpi 
Sets the resolution of the scanned image.
–source FlatBed|Automatic Document Feeder(left aligned)|Automatic Document Feeder(centrally aligned) [Automatic Document Feeder(left aligned)]
Selects the scan source (such as a document-feeder).
–brightness -50..50% (in steps of 1) [inactive]
Controls the brightness of the acquired image.
–contrast -50..50% (in steps of 1) [inactive]
Controls the contrast of the acquired image.
-l 0..211.9mm (in steps of 0.0999908) 
Top-left x position of scan area.
-t 0..355.6mm (in steps of 0.0999908) 
Top-left y position of scan area.
-x 0..211.9mm (in steps of 0.0999908) [211.881]
Width of scan-area.
-y 0..355.6mm (in steps of 0.0999908) [355.567]
Height of scan-area.