Introduction: TWAIN and ISIS® Input

TWAIN:

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.DLL for 16-bit or TWAIN_32.DLL for 32-bit. These files must be obtained from the TWAIN device manufacturer.

ISIS [Document/Medical]:

The Image and Scanner Interface Specification (ISIS) is a standard for scanner control and provides a complete framework for image processing. LEADTOOLS supports image acquisition from ISIS scanner drivers. The ISIS interface is message based, using tags to get and set scanner information and operating parameters.

LEADTOOLS provides ISIS Scanner support which allows you to determine if ISIS is available, load and unload ISIS Scanner Drivers, select and/or add an ISIS Scanner Driver through a dialog, scan one or more pages and save the images to files, and get or set Scanner Driver tags. These tags provide information about the scanner and let you set parameters pertaining to scanning, such as contrast, brightness, resolution, compression method, etc. With multipage scanning, you can code a callback function to provide a status report or cancel the operation.

Please note that ISIS support requires PIXDFLTN.DLL, which is not included with this package. This file must be obtained from the ISIS device manufacturer. Also note that you must obtain an ISIS driver from the scanner manufacturer or from Pixel Translations. The .chn or .chw file must be in your path for ISIS scanning to work. LEAD does not grant any license to the ISIS driver or to ISIS development capabilities. It is your responsibility to obtain the appropriate license to your development project, either from Pixel Translations, or one of their licensees. For more information on using ISIS, refer to Using ISIS to Scan Images.