If you are loading a multi-page image file, you should set the maximum number of images that can be held in Dynamic Web TWAIN by using the MaxImagesInBuffer property. Then you can use the LoadImage method or the LoadImageEx method to load images into Dynamic Web TWAIN (DWT).

Code:

//JavaScript
function btnLoad_onclick()
{
     frmScan.DynamicWebTwain1.LoadImage("G:\\wwwroot\\test.tiff"); 
}

Please make sure that the image file is created by DWT or Dynamic TWAIN (DT). Currently, we only ensure that images created by DWT or DT can be loaded into DWT.

Reference:

MaxImagesInBuffer LoadImage  LoadImageEx