TwainSave and TWAIN information
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There are a few things that must be aware of before running TwainSave. If you are having a problem running TwainSave, the issues described below may address the problems you may be having with TwainSave.
TwainSave only works for devices that have TWAIN drivers. If your scanner, digital camera, webcam, etc. does not come with a TWAIN driver, TwainSave will not work for that device.
TwainSave will not work for devices that do not have a TWAIN driver. This means that if your device is "dead", i.e. missing the TWAIN driver, TwainSave isn't going to work. The TWAIN driver for the device must be present, and installed correctly for the devices you are intending to use.
Also included in this list of devices that TwainSave will not work for includes scanners that are using ISIS drivers (many of these scanners however have TWAIN drivers, and TwainSave should work when using the TWAIN driver), and digital cameras that use their own Application Program Interface (API) or Software Development Kit (SDK). Many digital cameras include software development kits that are not TWAIN compliant.
TwainSave works best for devices that expose most of their functionality through the TWAIN driver (or in other words, just because you can press a button on the device to do "x", doesn't mean that you can do "x" using the TWAIN driver).
Even though a device may have a TWAIN driver, this does not necessarily mean that all of the functionality of the device is available through TWAIN. For example, a famous brand of scanner comes with a transparency adapter, but there is no TWAIN access to the adapter. TwainSave relies solely on the device's TWAIN driver to make the final communication with the device -- if the authors of the TWAIN driver did not add support for an aspect of the hardware of the device, there is nothing that TwainSave can do to rectify the problem. The solution is to get another device, or hopefully there is an upgraded TWAIN driver from the manufacturer.
Most Windows TWAIN drivers require a user to have "Administrator" or "Power user" access rights before accessing the device.
There are many TWAIN drivers that will not load and will fail to work properly if the user does not have access rights of "power user" or above. The reason is that these drivers attempt to modify files in directories that user's with lower access rights do not have permission to read/write to. Note that this problem is not with TwainSave -- it is an issue with the particular TWAIN driver(s) that will read/write to these directories when opened or accessed.
Depending on the driver, there may be different solutions. One such solution is obvious, and that is to make only users with power user or administrator rights to run TWAIN-enabled programs such as TwainSave. Other solutions vary from discovering which directories are being accessed by the TWAIN driver and give access rights to that particular directory, and/or contact the manufacturer of the device for a resolution to the problem. In any event, TwainSave and other TWAIN-enabled applications cannot override what a particular driver does in terms of what directories are being accessed by the driver.
TwainSave works best for devices that follow the TWAIN specification as closely as possible.
Some TWAIN drivers are written very poorly, and do not follow the TWAIN specification 100% of the time. Therefore you may experience bad or undesired images being produced from such devices.
If you are running the bundled software that comes with your device, and it works correctly, but TwainSave doesn't work, do not be fooled!
Many of the programs that come bundled with the device have been written with full knowledge of known bugs that the device may have, and the creators of these programs know how to sidestep these bugs. Many of these programs do not even use TWAIN whatsoever. That is one reason why the manufacturer's bundled programs work.
On the other hand, TwainSave has no knowledge of these bugs, and instead makes calls to TWAIN with accordance to the TWAIN specification, exposing whatever bugs the hardware may have, or at the very least expose the bugs in the manufacturer's TWAIN driver . For example, the transparency adapter of a famous scanner manufacturer could not be accessed using TWAIN, but the bundled software that came with the scanner was able to use the transparency adapter. Another manufacturer listed a single available DPI resolution value in their TWAIN driver, however the physical scanner supported multiple resolutions (and of course, their "bundled software" supported all of these resolutions!). This is very frustrating, but again, there is nothing that TwainSave can do about this problem.
To verify if this is actually a TwainSave problem and not a problem with the device of TWAIN driver, try to use another program that uses TWAIN to access the device. For example the image file viewer, IrfanView (www.irfanview.com) has an "Acquire" mode that acquires images from the device (this also uses TWAIN). If the other third-party program works correctly, this is an indication that TwainSave should work also. If the third-party program has the same issues as TwainSave, this is evidence that the TWAIN driver for the device has bugs.
Acquiring images without the user-interface of the device being displayed requires a well-written TWAIN driver that supports this mode of operation.
Many TWAIN drivers do not support running without a user-interface. This is the case with a lot of digital cameras. Also, there are some drivers that do support runnning without displaying the device's user interface, however setting certain options such as resolution, gamma, contrast, etc. do not seem to work due to bugs in the TWAIN driver. Usually, high-end scanners have very good TWAIN drivers and have no problems running without the user interface displayed.
Windows WIA and STI drivers are not TWAIN drivers.
The newer WIA (Windows XP) and STI drivers that come with many devices made are not TWAIN drivers. WIA and STI does have a TWAIN compatibility mode, but this mode only supports a minimal subset of TWAIN. For example, you can't acquire multiple pages with the TWAIN support that a WIA driver gives you. Many of these TWAIN devices do however have full-fledged TWAIN drivers, where you get the most functionality.
In general, TwainSave should work with any TWAIN compatible device, as long as the device has a compliant TWAIN driver, and the TWAIN driver for the device has been installed correctly.