How to scan negatives using TWAIN scanner?

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Scan negatives using TWAIN scanner

If you want to scan negatives using TWAIN scanner, you should pass the WebLightPathEnumJS.Transmissive value to the the WebTwainDeviceJS.set_LightPath function.

Here is JavaScript code that demonstrates how to scan negatives using TWAIN scanner:

JavaScript

// scan negatives using TWAIN scanner
__scanNegativesUsingTwainScanner();



/**
 * Scans negatives using TWAIN scanner.
 */
function __scanNegativesUsingTwainScanner() {
    // register the evaluation version of VintaSoft Web TWAIN service
    // please read how to get evaluation license in documentation: https://www.vintasoft.com/docs/vstwain-dotnet-web/Licensing-Twain_Web-Evaluation.html
    Vintasoft.Twain.WebTwainGlobalSettingsJS.register('REG_USER', 'REG_URL', 'REG_CODE', 'EXPIRATION_DATE');

    // URL to the VintaSoft Web TWAIN service
    var serviceUrl = 'https://localhost:25329/api/VintasoftTwainApi';
    // a Web API controller that allows to work with TWAIN and SANE devices
    var twainService = new Vintasoft.Shared.WebServiceControllerJS(serviceUrl);

    // TWAIN/SANE device manager
    var deviceManager = new Vintasoft.Twain.WebTwainDeviceManagerJS(twainService);

    // the default settings of device manager
    var deviceManagerInitSetting = new Vintasoft.Twain.WebTwainDeviceManagerInitSettingsJS();

    var device = null;
    try {
        // open device manager
        deviceManager.open(deviceManagerInitSetting);

        // get the default TWAIN device
        device = deviceManager.get_DefaultDevice();

        // open device without UI
        device.open(false);

        // specify that color images must be acquired from TWAIN scanner
        device.set_PixelType(new Vintasoft.Twain.WebPixelTypeEnumJS("RGB"));
        // specify that negatives must be acquired from TWAIN scanner
        device.set_LightPath(new Vintasoft.Twain.WebLightPathEnumJS("Transmissive"));

        // a collection that stores images, which are acquired from TWAIN/SANE devices and stored in memory of VintaSoft Web TWAIN service
        var acquiredImages = new Vintasoft.Twain.WebAcquiredImageCollectionJS(deviceManager);
        var acquireModalState;
        do {
            // do one step of modal image acquisition process
            var acquireModalResult = device.acquireModalSync();
            // get state of image acquisition
            acquireModalState = acquireModalResult.get_AcquireModalState().valueOf();

            switch (acquireModalState) {
                case 2:   // image is acquired
                    // get acquired image
                    var acquiredImage = acquireModalResult.get_AcquiredImage();
                    // add acquired image to the image collection
                    acquiredImages.add(acquiredImage);

                    // get image as Base64 string
                    var bitmapAsBase64String = acquiredImage.getAsBase64String();
                    // update image preview
                    var previewImageElement = document.getElementById('previewImage');
                    previewImageElement.src = bitmapAsBase64String;

                    // clear image collection (delete images from memory of VintaSoft Web TWAIN service) because image is not necessary anymore
                    acquiredImages.clear();
                    break;

                case 4:   // image scan is failed
                    alert(acquireModalResult.get_ErrorMessage());
                    break;

                case 9:   // image scan is finished
                    break;
            }
        }
        while (acquireModalState !== 0);
    }
    catch (ex) {
        alert(ex);
    }
    finally {
        if (device != null) {
            // close the device
            device.close();
        }
        // close the device manager
        deviceManager.close();
    }
}

Here is TypeScript code that demonstrates how to scan negatives using TWAIN scanner:

TYPESCRIPT

import { Component } from '@angular/core';

@Component({
  selector: 'twain-scanning-demo',
  templateUrl: './twain-scanning-demo.component.html'
})
export class TwainScanningDemoComponent {

  ngOnInit() {
    // scan negatives using TWAIN scanner
    __scanNegativesUsingTwainScanner();
  }


  /**
   * Scans negatives using TWAIN scanner.
   */
  __scanNegativesUsingTwainScanner() {
    // register the evaluation version of VintaSoft Web TWAIN service
    // please read how to get evaluation license in documentation: https://www.vintasoft.com/docs/vstwain-dotnet-web/Licensing-Twain_Web-Evaluation.html
    Vintasoft.Twain.WebTwainGlobalSettingsJS.register('REG_USER', 'REG_URL', 'REG_CODE', 'EXPIRATION_DATE');

    // URL to the VintaSoft Web TWAIN service
    let serviceUrl: string = 'https://localhost:25329/api/VintasoftTwainApi';
    // a Web API controller that allows to work with TWAIN and SANE devices
    let twainService: Vintasoft.Shared.WebServiceControllerJS = new Vintasoft.Shared.WebServiceControllerJS(serviceUrl);

    // TWAIN/SANE device manager
    let deviceManager: Vintasoft.Twain.WebTwainDeviceManagerJS = new Vintasoft.Twain.WebTwainDeviceManagerJS(twainService);

    // the default settings of device manager
    let deviceManagerInitSetting: Vintasoft.Twain.WebTwainDeviceManagerInitSettingsJS = new Vintasoft.Twain.WebTwainDeviceManagerInitSettingsJS();

    try {
      // open device manager
      deviceManager.open(deviceManagerInitSetting);
    }
    catch (ex) {
      alert(ex);
      return;
    }

    let twainDevice: Vintasoft.Twain.WebTwainDeviceJS = null;
    try {
      // get the default TWAIN device
      twainDevice = deviceManager.get_DefaultDevice();

      // open device without UI
      twainDevice.open(false);

      // specify that color images must be acquired from TWAIN scanner
      twainDevice.set_PixelType(new Vintasoft.Twain.WebPixelTypeEnumJS("RGB"));
      // specify that negatives must be acquired from TWAIN scanner
      twainDevice.set_LightPath(new Vintasoft.Twain.WebLightPathEnumJS("Transmissive"));

      // a collection that stores images, which are acquired from TWAIN/SANE devices and stored in memory of VintaSoft Web TWAIN service
      let acquiredImages: Vintasoft.Twain.WebAcquiredImageCollectionJS = new Vintasoft.Twain.WebAcquiredImageCollectionJS(deviceManager);
      let acquireModalState: number;
      do {
        // do one step of modal image acquisition process
        let acquireModalResult: Vintasoft.Twain.WebTwainDeviceAcquireModalResultJS = twainDevice.acquireModalSync();
        // get state of image acquisition
        acquireModalState = acquireModalResult.get_AcquireModalState().valueOf() as number;

        switch (acquireModalState) {
          case 2:   // image is acquired
            // get acquired image
            let acquiredImage: Vintasoft.Twain.WebAcquiredImageJS = acquireModalResult.get_AcquiredImage();
            // add acquired image to the image collection
            acquiredImages.add(acquiredImage);

            // get image as Base64 string
            let bitmapAsBase64String: string = acquiredImage.getAsBase64String();
            // update image preview
            let previewImageElement: HTMLImageElement = document.getElementById('previewImage') as HTMLImageElement;
            previewImageElement.src = bitmapAsBase64String;

            // clear image collection (delete images from memory of VintaSoft Web TWAIN service) because image is not necessary anymore
            acquiredImages.clear();
            break;

          case 4:   // image scan is failed
            alert(acquireModalResult.get_ErrorMessage());
            break;

          case 9:   // image scan is finished
            break;
        }
      }
      while (acquireModalState !== 0);
    }
    catch (ex) {
      alert(ex);
    }
    finally {
      if (twainDevice != null) {
        // close the device
        twainDevice.close();
      }
      // close the device manager
      deviceManager.close();
    }
  }

}

Scan negatives using SANE scanner

If you want to scan negatives using SANE scanner, you should set the scan mode allowing to scan negatives, for example, HP scanners have "Negative" scan mode. The scan mode of SANE scanner can be set using the WebTwainDeviceJS.set_SaneScanMode function.

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