Compare PDF, DWF and CAD Drawings Automatically with scConverter SDK

Compare your files and save the comparison result to a PDF, PNG or TIFF file

The scConverter SDK can automatically compare PDF files, DWF drawings, CAD files, TIFF images, Gerber files and many other technical document formats. The comparison engine highlights added, removed and unchanged content using customizable colors and can save the result as PDF, PNG or TIFF.

What scConverter Document Comparison Does

scConverter compares two input files and creates a visual output file showing the differences between them. For example, when comparing two PDF drawing revisions, removed content can be displayed in red and new content can be displayed in blue. Unchanged content can be displayed in black, gray or hidden completely.


The comparison result can be saved to several output formats, including PDF, PNG and TIFF. This allows the result to be archived, reviewed, printed, emailed or included in an automated document workflow.


Available Comparison Functions

scConverter provides two main API functions for file comparison:

In this small tutorial you will find out how you can use these two functions create a PDF comparison.


Compare two PDF files

The following example compares two PDF revisions and creates a new PDF file that highlights all changes. Deleted or old content is drawn in red, while added or new content is drawn in blue. Unchanged content is drawn in black. 

   scconverter.SetSerialNumber( "Your serial number" );      
   scconverter.PDFWriteFormat = 0;     //Output standard editable PDF   
   scconverter.SaveCompareResult( "compare_revA.pdf", "compare_revB.pdf", "output1.pdf", "PDF", 0x000000FF, 0x00FF0000, 200 );

In this example, the comparison is created using a resolution of 200 DPI. A higher DPI value may improve output quality, but it will also increase memory usage and the size of the generated output file.

The PDF file created by our code will look like the following:


PDF compare result

Make Unchanged Content Easier to Ignore

If the drawing or document contains a lot of content, it may be difficult to see the actual changes immediately. In that case, you can use SaveCompareResultEx and draw unchanged content in a lighter color. 

   scconverter.SaveCompareResultEx( "compare_revA.pdf", "compare_revB.pdf", "output2.pdf", "PDF", 
                                     0x000000FF, 0x00FF0000, 0x00D0D0D0, 200);

This code will create a output PDF file named "output2.pdf" as shown below:


Using light gray for unchanged content makes drawing revisions easier to identify

Show Only the Changed Content

For some workflows, you may want the output file to show only the differences between the two files. This can be done by setting the unchanged content color to white. 

   scconverter.SaveCompareResultEx( "compare_revA.pdf", "compare_revB.pdf", "output3.pdf", "PDF", 
                                    0x000000FF, 0x00FF0000, 0x00FFFFFF, 200);

This code will create a output PDF file named "output3.pdf" as shown below:


Comparison result where unchanged content is hidden by using white as the unchanged color

Compare More Than PDF Files

Although PDF comparison is a common use case, scConverter can compare many other file formats supported by the SDK. This is useful when working with technical drawings, engineering documents, image files, PCB manufacturing files or mixed-format document archives.

Supported comparison input formats include:

Typical Use Cases

Engineering Revision Comparison

Compare two versions of a technical drawing and highlight what has changed between revisions.

PDF Difference Reports

Generate PDF comparison reports that can be reviewed, archived or sent to customers and suppliers.


Quality Assurance

Use automated comparison to validate document changes before production, approval or release.

Server-Side Processing

Integrate document comparison into automated systems, batch jobs or document management workflows.

Why Use scConverter for Document Comparison?

scConverter is designed for developers who need to add advanced document processing functionality to their own software. Unlike simple image comparison tools, scConverter is suitable for technical and engineering documents where formats such as PDF, DWF, TIFF, PLT, CGM and Gerber are commonly used.


The SDK gives your application control over the input files, output format, colors, resolution and comparison result. This makes it suitable for custom applications, automated workflows, server solutions and specialized engineering systems.

Development Platform Support

scConverter can be used from several development environments, including:

Frequently Asked Questions

Can scConverter compare PDF files automatically?

Yes. scConverter can compare two PDF files and generate a visual comparison result as PDF, PNG, JPEG or TIFF.


Can scConverter compare DWF and CAD drawings?

Yes. scConverter can compare DWF, DWFX and other supported technical drawing formats.


Can I customize the comparison colors?

Yes. You can define the colors used for old content, new content and unchanged content.


Which output formats are supported?

Comparison results can be saved as PDF, PNG, JPEG or TIFF.


Can scConverter be used in server applications?

Yes. scConverter can be integrated into desktop applications, server systems, batch processing tools and automated document workflows.



Download and Evaluate scConverter

If you need to add PDF, DWF, CAD or technical document comparison to your own application, scConverter may be the solution you are looking for.


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You can also learn more about the scConverter SDK here.