Scanners are typically accessed through interfaces such as SCSI, USB, and networks. To control a scanner to perform scanning tasks and return scanned data, a set of standards must be followed. Modern scanners generally support the eSCL standard for network connections. However, not all scanners comply with this standard; manufacturers often define their own protocols and provide drivers for applications to use.

But drivers are not always available for all operating systems and CPU architectures. As a result, some people have reverse-engineered these protocols, enabling the use of scanners without official drivers. Examples of such software include the open-source SANE and commercial options like ExactScan and VueScan. Additionally, writing custom drivers allows precise control over scanners, such as adjusting colors, enabling or disabling paper jam detection sensors, and previewing scan results in real time. Moreover, with browsers now supporting USB device control, it is even possible to operate scanners directly within a browser.

Below are some methods for reverse engineering scanners:

  1. Directly Leverage SANE’s Source Code: SANE has reverse-engineered most scanners. By studying its code, we can understand the communication methods of various scanners.

  2. Capture USB Traffic in an Environment with Working Drivers: For example, here’s how to do it on Linux:

    Start capturing:

    sudo modprobe usbmon
sudo tcpdump -i usbmon2 -w scan.pcap

    Use SANE to scan a document:

    scanimage -o t.jpg -l 0 -t 0 -x 5 -y 5

    Then press Ctrl+C to terminate capturing command and save the results. Finally, analyze the results using WireShark.

    This method requires strong analytical skills regarding the USB protocol and is relatively challenging.

Using Qoder, I had AI write a Python program based on SANE’s Pixma driver to control the Canon Lide 300 via Python and libusb. I tested and it works: https://github.com/xulihang/Canon-Lide-300-Python-USB-Driver.

For general users, it’s simpler to use existing scanning software, such as ImageTrans, which supports various scanning APIs like TWAIN, WIA, ICA, SANE, and eSCL. It allows users to operate most scanners across different operating systems. Scanned documents can then be further processed for tasks like translation, OCR, and generating searchable PDFs.