Technical FAQs for "SDK"

ImageGear .NET v24.6 added support for viewing PDF documents with XFA content. I’m using v24.8, and upon trying to open an XFA PDF, I get a SEHException for some reason…

Why might this be happening?

One reason could be because you need to execute the following lines after initializing the PDF component, and prior to loading an XFA PDF:

// Allow opening of PDF documents that contain XFA form data.
IImGearFormat pdfFormat = ImGearFileFormats.Filters.Get(ImGearFormats.PDF);
pdfFormat.Parameters.GetByName("XFAAllowed").Value = true;

This will enable XFA PDFs to be opened by the ImageGear .NET toolkit.

We are saving files to the PDF/A standard and are running into a few cases where the file cannot be saved as PDF/A by ImageGear .NET. Why is this, and how do we do it properly?

First, determine whether a PDF document can be converted to PDF/A by creating an ImGearPDFPreflight object from your document, and generating an ImGearPDFPreflightReport object from it:

using (ImGearPDFPreflight preflight = new ImGearPDFPreflight((ImGearPDFDocument)igDocument))
{
    report = preflight.VerifyCompliance(ImGearPDFPreflightProfile.PDFA_1A_2005, 0, -1);
}

The first argument of the VerifyCompliance() method is the standard of PDF/A you want to use. ImageGear .NET is currently able to convert documents to adhere to the PDF/A-1A and PDF/A-1B standards:

PDF/A-1 Standard

ImageGear and PDF/A

There are parts of the PDF/A-2 and PDF/A-3 standards which may allow for more documents to be converted, but ImageGear .NET currently does not support those. This could possibly be why your document cannot be converted in ImageGear .NET.

Once the report is generated, you can access its Status, which will tell you if the document is fixable. You can also access its Code which will let you know if it’s a fixed page or if it has issues; it will return Success if fixed, or some error code otherwise. You can check these conditions to determine whether it’s worth attempting to convert the document:

// If the document is not already PDFA-1a compliant but can be converted
if ((report.Code == ImGearPDFPreflightReportCodes.SUCCESS) ||
(report.Status == ImGearPDFPreflightStatusCode.Fixable))
{
    ImGearPDFPreflightConvertOptions pdfaOptions = new ImGearPDFPreflightConvertOptions(ImGearPDFPreflightProfile.PDFA_1A_2005, 0, -1);
    ImGearPDFPreflight preflight = new ImGearPDFPreflight((ImGearPDFDocument)igDocument);
    preflight.Convert(pdfaOptions);
    saveFile(outputPath, igDocument);
}

// Create error message if document was not converted.
else if (report.Status != ImGearPDFPreflightStatusCode.Fixed)
{
    printAllRecordDescriptions(report);
    throw new ApplicationException("Given PDF document cannot be converted to PDFA-1a standard.");
}

If you want more information on why a document may not be convertible, you can access the preflight report for its records and codes. A preflight’s "Records" member is a recursive list of preflight reports. A preflight report will have a list of reports under Records, and each of those reports may have more reports, etc. You can recursively loop through them as seen below to output every reason a document is not convertible:

    private static void printAllRecordDescriptions(StreamWriter file, ImGearPDFPreflightReport report)
    {
        foreach (ImGearPDFPreflightReport rep in report.Records)
        {
            file.WriteLine(rep.Description);
            file.WriteLine(rep.Code.ToString() + "\r\n");
            printAllRecordDescriptions(file, rep);
        }
    }

Ultimately, the failure of a document to convert to PDF/A is non-deterministic. While some compliance failures can be corrected, in combination they may not be correctable. Therefore, the unfortunate answer is that to determine if it can be converted, conversion must be attempted.

In ImageGear, why am I running into AccessViolationExceptions when I run my application in parallel?

This issue can sometimes occur if ImGearPDF is being initialized earlier in the application. In order to use ImGearPDF in a multi-threaded program, it needs to be initialized on a per-thread basis. For example, if you have something like this:

ImGearPDF.Initialize();
Parallel.For(...)
{ 
    // OCR code
}
ImGearPDF.Terminate();

Change it to this:

Parallel.For(...)
{
    ImGearPDF.Initialize();
    // OCR code
    ImGearPDF.Terminate();
}

The same logic applies to other ImageGear classes, such as ImGearPage instances or the ImGearRecognition class – you should create one instance of each class per thread, rather than creating a single instance and accessing it across threads. In the case of the ImGearRecognition class, you’ll have to use the createUnique parameter to make that possible e.g.:

ImGearRecognition recEngine = ImGearRecognition(true);

instead of

ImGearRecognition recEngine = ImGearRecognition();

How do I remove XMP Data from my image using ImageGear .NET?

When removing XMP data in ImageGear, the simplest way to do this is to set the XMP Metadata node to null, like so:

ImGearSimplifiedMetadata.Initialize(); 
doc.Metadata.XMP = new ImGearXMPMetadataRoot();

Or, you can traverse through the metadata tree and remove each node from the tree:

// Example code. Not thoroughly tested
private static void RemoveXmp(ImGearMetadataTree tree)
{
ArrayList toRemove = new ArrayList();
foreach (ImGearMetadataNode node in tree.Children)
{
    if (node is ImGearMetadataTree)
        RemoveXmp((ImGearMetadataTree)node);

    if (node.Format != ImGearMetadataFormats.XMP)
        continue;

    toRemove.Add(node);
}

foreach (ImGearMetadataNode node in toRemove)
    tree.Children.Remove(node);
}

How do I change the default directory of the SmartZone folder from %TEMP% to something else?

As SmartZone runs, it will create a folder in the %TEMP% directory containing a few files that the engine needs to run. If you want to change this location, you can do that by creating an INI file in the same directory as the executable that runs your application. You must name that INI file smartzoneengineloader.ini. The contents of smartzoneengineloader.ini should look like this:

[smartzoneengineloader] tempdir = C:\Your\Path\Here\

Why do I get a “File Format Unrecognized” exception when trying to load a PDF document in ImageGear .NET?

You will need to set up your project to include PDF support if you want to work with PDF documents. Add a reference to ImageGear24.Formats.Pdf (if you’re using another version of ImageGear, make sure you’re adding the correct reference). Add the following line of code where you specify other resources:

using ImageGear.Formats.PDF;

Add the following lines of code before you begin working with PDFs:

ImGearFileFormats.Filters.Insert(0, ImGearPDF.CreatePDFFormat());
ImGearPDF.Initialize();

The documentation page linked here shows how to add PDF support to a project.

What does it mean when I see “Email Address is not Registered” when entering in an email in the Evaluation Dialog?

You will see this error if you have not registered on the Accusoft website.

To register your email address, please visit the following link below:

https://my.accusoft.com/Account/FirstTimeUser?Length=7

How do I ensure temp files are deleted when closing ImageGear .NET?

All PDF objects are based on underlying low-level PDF objects that are not controlled by .NET resource manager and garbage collector. Because of this, each PDF object that is created from scratch should be explicitly disposed of using that object’s Dispose() method.

Also, any ImGearPDEContent object obtained from ImGearPDFPage should be released using the ImGearPDFPage.ReleaseContent() in all cases.

This should cause all temp files to be cleared when the application is closed.

How can I improve the performance and memory usage of scanning/recognition in Barcode Xpress?

Barcode Xpress supports a number of optimization settings that can improve your recognition performance, sometimes up to 40%, along with memory usage. The best way to optimize Barcode Xpress is to fine-tune the properties of the Reader class to be specific to your application’s requirements.

BarcodeTypes

• The best way to increase performance is to limit which barcodes Barcode Xpress should search for. By default, BarcodeTypes is set to UnknownBarcode which targets all 1D barcodes.

MaximumBarcodes

• This property will instruct Barcode Xpress to halt searching after finding a specified number of barcodes. The default value is 100.

Area & Orientation

• If you know the location or orientation of your barcodes in your image, specifying an orientation (such as Horizontal) and area can prevent Barcode Xpress from searching for vertical or diagonal barcodes, or in places where barcodes would not exist.

ScanDistance

• Raising this value increases performance by applying looser recognition techniques by skipping rows of an image. However, this may fail to detect barcodes.

Finally, BarcodeXpress Professional edition does not impose a 40 page-per-minute limit on processing.

What quality should my images be for processing form data and recognition using FormSuite?

In all cases, you want to have your images as clear and as clean as possible. For any particular procedure, please consider the following:

OCR and ICR: Capture images in at least 300 DPI resolution. Ideally, working in black and white allows the objects of interest on your image to be better defined and recognized. Free the image form all noise as much as possible. As if a human were reading it, you want the text objects on the image to be as legible as possible. For ICR, ensure that the characters are printed (no cursive text, etc).

Barcode recognition: As with OCR and ICR, capture images in at least 300 DPI and working with black and white content can provide excellent results. Ensure that the bars in the barcodes are clearly defined on the image and are not malformed (for example, the barcodes should have the proper start and stop sequence, etc). Clear as much noise from the image as possible.

Forms matching and registration: As with the prior 2 items above, capture your documents in at least 300 DPI. Ensure that your resolution is consistent between your form templates and incoming batch images. Form templates should only contain data that is common to every image that is being processed (i.e. Form fields, the text that appears on the blank form itself, etc). The template should not have filled-in field information as this will affect the forms matching process.

The ISIS Xpress BasicCapabilities and AdvancedCapabilities samples demonstrate a number of different ways to acquire images and save a batch of them to file, but how can I get a single image as soon as it gets acquired by the scanner?

During the ISIS Xpress Scanned() event, you can get the currently acquired page via the ISISXpress.Output property (i.e., – ISISXpress.Output.TransferTo() or ISISXpress.Output.ToHdib()).

How do I use a Network Drive path for Image and ART storage in my ImageGear .NET web application?

In an ImageGear .NET web application, you have to define the location of the images and annotations directory in the storageRootPath and artStorageRootPath configuration property.
In the current version of ImageGear .NET, the storageRootPath and artStorageRootPath do not work with a network drive path \\SERVER-NAME\sharefilename.

The workaround for this would be to create a Symbolic link from a local directory to the network drive directory.

• To create a symbolic link: Open “Command Prompt” as Administrator and type in > mklink /d "local path" \\SERVER-NAME\sharefilename
• Pass in the path of the symbolic link as image or art storage root path in your web.config: storageRootPath="local path" artStorageRootPath="local path"