Acquiring Images without a User Interface

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Once the device has been selected using one of the selection options, TwainSave has various options to acquire image files without showing the user interface for the TWAIN device.  This is convenient in that there is no user intervention required to start acquiring the images.


The following options are used to acquire without a user interface:





In addition to these options, the -showindicator option can be used to either show or hide the progress indicator when acquiring without a user-interface.


Please note that a TWAIN device must fulfill all the requirements that the TWAIN protocol has set forth before it can be used to acquire without a user interface.  Not all TWAIN drivers allow acquisition without a user interface (many TWAIN digital cameras and older TWAIN compliant scanners may not allow disabling the user interface).


In addition to the above, a TWAIN driver must be implemented at a reasonably high-level of sophistication to properly allow acquiring without a user interface, much more so than acquiring with a user-interface.  In this regard, many TWAIN drivers can be faulty when used in a "no user interface" mode.  Therefore it is recommended that you use recent TWAIN compliant hardware and ensure you're using the latest TWAIN drivers from the manufacturer of the hardware.


One last point when acquiring without a user interface:

A mistake we have seen users of TwainSave make is to assume that the TWAIN device automatically knows what options to set to produce a "good" image when no user interface is chosen.  This is not the case.  Since no user interface is shown, your TwainSave command must specify all the necessary options to acquire the images correctly (or at least to make them satisfactory for viewing).  For example, setting the color, resolution, bit depth, and other aspects of the device must be done by the TwainSave command-line options.  Without a user interface to help set the options, you are responsible for setting any of the desired options yourself using the TwainSave command-line options.


If these options are not specified, the image acquired will be using the device's default values for these options.  For example, if the device's default resolution is 200 DPI, and your command-line doesn't specify the resolution (-resolution), your image will be 200 DPI and thus may not be satisfactory for viewing.  To override this, you must specify the -resolution command to set the resolution.