TWAIN, WIA and ISIS are scanner drivers that most manufacturers support and make in order for a scanner to acquire a physical image and convert it to an electronic image that can be stored on a computer. Why so many types you ask? I ask the same question all the time but this is something that has evolved over time.

TWAIN

the most commonly used program that lets you scan an image (using a scanner ) directly into an application (such as Adobe PDF, Foxit Reader and More) where you want to digitize the image. Without a TWAIN driver, you need to close or minimize an application that was open, open a special scanning application to receive the image, and then move the image to the application where you want it stored. The TWAIN driver is a software that connects between an application and the scanner. TWAIN usually comes as part of a software package you get when you buy a scanner. Most applications today are enabled to see a TWAIN driver.

The software was developed by a work group from major scanner manufacturers and scanning software developers and is now an industry standard. You can read more about this interface on www.twain.org.

WIA –

Windows Image Acquisition (WIA) is the main driver platform in the Windows family of operating systems starting with Windows Millennium Edition (Windows Me) and Windows XP. The WIA platform supports and enables imaging/graphics applications to connect with imaging hardware and standardizes the interaction between different applications and scanners. This sounds just like TWAN doesn’t it? WIA allows those different applications to connect different scanners without requiring the application writers and scanner manufactures to customize their application or drivers for each application-device combination. Technically with WIA you should not have to install the driver that comes with a scanner, just connect it and it works. Unfortunately that is not always the case.

Differences TWAIN and WIA:

1. WIA uses a common dialog for all devices while TWAIN uses a dialog created by the device manufacturer.  This gives a closer integration and control to the TWAIN driver giving more options and advanced features on the hardware (scanner) used.
2. TWAIN allows you to use custom capabilities that the device manufacturer has created even though they don’t exist in the TWAIN specifications.
3. In general, when a device supports both Twain and WIA, TWAIN is better for scanners and WIA is better for acquiring images from cameras and video devices.
4. TWAIN has three transfer modes (Native, Memory, File) and WIA only has two (Memory, File).
5. Most TWAIN sources save the settings of a previous scan while WIA has limited functionality and does not.
6. TWAIN supports options for each page when scanning in duplex mode, WIA uses the same settings for both sides.

TWAIN is usually the most flexible programmable and accepted method throughout the industry over WIA.

ISIS

is a proprietary scanner interface developed by Pixel Translations, Inc. unlike TWAIN that is a standard scanner interface developed by a non-profit consortium, ISIS drivers are made for profit.  Many vendors are moving away from ISIS since one has to pay a royalty to include ISIS drivers in one’s software.

In our years of imaging expertise we have seen no technical advantage to using ISIS or TWAIN. Both produce a quality image. If you compare two scanned images from TWAIN and ISIS drivers that have been scanned under normal circumstances (which is 90% of the workflow we see in the field), you will not be able to tell the difference. Only one company develops ISIS drivers (Pixel Translations, Inc.), whereas most scanner vendors develop their own TWAIN drivers and keep them up to date.

Some developers do believe that ISIS is a better all around driver and theoretically will work more consistently with all software that supports the ISIS interface). Experience has shown us that there is a wide variety of quality of TWAIN drivers out there, so one TWAIN driver may work very well with many software packages, whereas another TWAIN driver may be very fragile, and not work as consistently well with different packages.  Industry perception however states that TWAIN is a great solution for low volume and ISIS works well for high volume scanning. ISIS is mainly recommended for high-speed document scanners over 40 pages per minute.

Final Recommendation

Full disclosure, OCR makes a remote twain driver thus you may think we are bias towards the twain driver. When we began development of VirtualScan it was actually programmed as a WIA driver, after several installations we saw that TWAIN was the overall winner in feature set and stability. This is why as a company we have this bias towards TWAIN. ISIS is around but is not popular in small the medium and even large enterprises. Unless you have a specific requirement for WIA or ISIS our recommendation is to go with TWAIN drivers used by approximately 90% of the scanners and applications on the market. If you are in the market for a superior scanner for a reasonable price, please take a look at our Avision Scanners line.


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