Getting my Mustek ScanExpress A3 Tabloid Scanner working under Photoshop CS4 on Mac OSX

I'd purchased a second-hand Mustek ScanExpress A3 scanner from Craigslist. This scanner is a bit old, has pretty bad color gamut (which is easily fixed in Photoshop), but has a huge scanning area. It can scan a 11"x17" sheet in it's entirety, without stitching. For this feature alone, I deemed this product worthy of daily use.

I use this scanner primarily to scan album covers for my Vinyl to CD conversion service. It does require 2 scans per album side, as vinyl album covers tend to measure 12.5" x 12.5". Compared to 4 scans per side when using a smaller (letter sized) scanner, this is a huge time saver.

If you have a legacy scanner like this, there is support for these old artifacts with a modern machine. While this scanner claims to be unsupported under Mac OS X, you can use some open-source software to bridge the divide. Today, I'll introduce you to TWAIN & SANE.

TWAIN literally means 'Technology Without An Interesting Name'. What is does however, is act as a standard for image acquisition. Most modern scanners and computers both support TWAIN drivers. They're cross-platform and generally stable.

SANE is shorthand for 'Scanner Access Now Easy'. With possibly the ugliest logo out there, (and cryptic too, what is it?) this software is supposed to simplify working with scanners that don't have drivers.

There's several packages you need to install, and in a very specific order, so I suggest you read all these instructions before beginning!

Let's Go!

Install TWAIN

Grab your OS appropriate drivers from this site: They support up to Mac OS 10.6, so you can get legacy devices working with the newest machines! Install the packages in the following order:

  1. libusb.pkg
  2. sane-backends.pkg
  3. twain-sane-interface.pkg
  4. sane-preference-pane.pkg

You'll be asked for your admin password each time you install... Tedious!

Scanner Driver

Grab the Mustek specific drivers from here: and copy to your desktop. In my case, I downloaded the file named 'a32fw.usb'.

Configure SANE

  1. Go into system preferences, click on the SANE icon.
  2. Find the gt68xx line and click the configure button.
  3. A terminal window will open. Scroll to find the part that says this:

    #Autodetect Mustek ScanExpress A3 USB
    usb 0×055f 0×0210

    # Mustek ScanExpress A3 USB doesn’t need any manual settings

  4. Delete the “#”’s and click Okay.
  5. You’ll probably have to enter your system password.
  6. Then find the gt68xx line in your SANE window again and click the firmware button.
  7. This will open up another terminal window. Drag that 'a32fw.usb' file off your desktop into the terminal window, and save it.
  8. Shut down.
  9. Plug your Mustek’s USB cord into your computer.
  10. Turn it on.

Install TWAIN Plug-in in Photoshop CS4 or CS5

Download the TWAIN Photoshop Plugin from Adobe, but follow the instructions and warnings about the software, as well.

  1. Quit Photoshop CS4.
  2. Copy the TWAIN plug-in from the //Goodies/Optional plug-ins/Import-Export folder on your installation media into the /Adobe Photoshop CS4/Plug-ins/Import-Export folder on your hard disk.
  3. Restart Photoshop to enable the plug-in.
  4. Open IMPORT from the FILE menu and hit SANE

Looking for Support?

Figure it out on your own - I am not going to help you figure out why you can't do it and I can. RTFM! I've turned off comments to dissuade those folk seeking free tech support from contacting me. The instructions above worked for me, several times on different Macs with equally perfect results.

This scanner (and these instructions) are unsupported by Mustek (the manufacturer), Apple (the CPU), Adobe (the App), and me (the writer).

Photoshop CS5 Update

Turns out this works under the CS5 version of Photoshop as well, with one small caveat: You need to run the application in 32-bit mode, otherwise the TWAIN and SANE plug-ins don't work (as they are written in 32-bit mode). To do this, simply find the Photoshop application in your Applications folder, select the app, then File > Get Info (Command-I) the application. See the check-box allowing you to run in 32-bit mode? Check it, and re-run the application. The plug-ins should now work! You can click the screen shot embedded to the right to see where the 32-bit mode is.