Separate Scan document method (1) - Dynamic Web TWAIN: How to use a blank page as a separator scanned documents

Scenarios

You want to connect the scanner in a Web page, document scanning in a web page. When you scan multiple documents one time, there is a blank page to separate them between each document, and you want to save the document separately in each section of the document after scanning completely.

solution

Use Dynamic Web TWAIN SDK, you can quickly achieve page document scanning using blank pages document separation.

Implementation steps

Step 1: Download and install Dynamic Web TWAIN 30-day free trial version

Application download link: https://www.damingsoft.com/products/dwt-register.aspx

Step 2: build Web pages scanned pages

After installation is complete can in C: \ Program Files (x86) \ Dynamsoft \ Dynamic Web TWAIN SDK {version} Trial \ find a UseEvent.html of Samples \ Getting Started in the sample page. Double-click to open it to achieve the most simple web page scanning.

If you want to build yourself a web page scanning, refer to the documentation: https://www.damingsoft.com/docs/dwt/Dev-Guide/Build-the-Hello-World-Scan-Page.html

Step 3: determine a blank page and save the document

To do this, we will scan all the documents, and then use the interface IsBlankImageExpress (index) to detect whether it is empty. If the page is blank, we will remove it and save the buffer on a set of documents. To accomplish this task, we will use the event OnPostAllTransfers, it triggers the scan is complete, after all, to see if there are any empty page.

At this point, we can open UseEvent.html, its code will be little change. function Dynamsoft_OnReady changes are as follows:

        function Dynamsoft_OnReady() {
            DWObject = Dynamsoft.WebTwainEnv.GetWebTwain('dwtcontrolContainer');    // Get the Dynamic Web TWAIN object that is embeded in the div with id 'dwtcontrolContainer'
            //DWObject.Width = 270;       // Set the width of the Dynamic Web TWAIN Object
            //DWObject.Height = 400;      // Set the height of the Dynamic Web TWAIN Object
            if (DWObject) {
                DWObject.RegisterEvent('OnPostAllTransfers', CheckBlankPage);      // Register OnPostAllTransfers event. This event fires when all pages have been scanned and transferred                    
            }
        }

Add function CheckBlankPage:

function CheckBlankPage() { //Function for checking a blank page, called when OnPostAllTransfers is triggered
    if (DWObject) {//Ensure there is a DWObject
        var startindex = 0;
        for (var i = 0; i < DWObject.HowManyImagesInBuffer; i++) {//Go through each image in the buffer.
            if (DWObject.IsBlankImageExpress(i)) {
                DWObject.RemoveImage(i);// remove the blank page from the buffer.
                if (i != 0) {
                    i--; //decrement i for the removed image
                    DWObject.SelectedImagesCount = (i - startindex + 1); // set how many images are selected
                    for (var j = 0; j < DWObject.SelectedImagesCount; j++) { //loop to select all images from previous blank to current
                        DWObject.SetSelectedImageIndex(j, j + startindex);
                    }
                    if (DWObject.SelectedImagesCount > 0) { //save images as long as there are some in the selection
                        DWObject.IfShowFileDialog = true;
                        var randomId = (Math.floor(Math.random() * 1000 + 1)).toString();
                        DWObject.SaveSelectedImagesAsMultiPagePDF(randomId + ".pdf");//PLEASE CHANGE THIS FILE PATH
                    }
                    startindex = i + 1; //set the start index for next search 1 higher than current page
                }
            }
            else if (i == DWObject.HowManyImagesInBuffer - 1) {//the last few images are not blank
                DWObject.SelectedImagesCount = (i - startindex + 1); // set how many images are selected
                for (var j = 0; j < DWObject.SelectedImagesCount; j++) { //loop to select all images from previous blank to current
                    DWObject.SetSelectedImageIndex(j, j + startindex);
                }
                if (DWObject.SelectedImagesCount > 0) { //save images as long as there are some in the selection
                    DWObject.IfShowFileDialog = true;
                    DWObject.SaveSelectedImagesAsMultiPagePDF("AllInOne.pdf");//PLEASE CHANGE THIS FILE PATH
                }
            }
        }
    }
}

If your application is difficult to detect a blank page (blank page around the edges of some non-white point), or if you are using a color page, you may need to use the standard deviation of the page. Instead, you can use the following code snippet:

function CheckBlankPage(){ //Function for checking a blank page, called when OnPostAllTransfers is triggered 
    if(DWObject){//Ensure there is a DWObject 
        for(var i = 0; i < DWObject.HowManyImagesInBuffer;i++){//Go through each image in the buffer. 
            if(DWObject.IsBlankImageExpress(i)){}//Make Blank Image run, but do not use the result 
            if(DWObject.BlankImageCurrentStdDev < 15.0){//set a standard deviation for the program to use
                //...... same as above code
            } 
        } 
    } 
}

to sum up

Through the above method, you can easily achieve page document scanning, and use the blank pages between documents document separation.

Of course, some application scenarios to separate documents not sign blank pages in a document, but the bar code or two-dimensional code. This is one document separation method, and can be achieved through Dynamic Web TWAIN and add-ons Barcode Reader. We will introduce after the article.