Introduction: TWAIN Input


TWAIN is a standard for image input devices, such as scanners and digital cameras. Getting an image from a TWAIN device can be very simple. First, there is a standard facility for selecting the input device. It is similar to selecting a default printer, and you can skip this step if you know that the default is right. Then, each TWAIN device has its own user interface, which you invoke to acquire an image.

Some complexity is introduced only when acquiring multiple images or when bypassing the user interface. If you acquire multiple images, you must code a callback function or event procedure to handle each image. If you bypass the user interface, you must set some standard TWAIN parameters to provide the information that the TWAIN driver would normally get from the user interface. The tricky part is that some TWAIN drivers implement the standard more fully than others. If you do not know in advance how the TWAIN device will behave, it is a good idea to add logic to your program to test the success of setting the TWAIN parameters. LEADTOOLS provides functions for all of this.

Please note that TWAIN support requires TWAIN_32.DLL for 32-bit. These files must be obtained from the TWAIN device manufacturer.

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