GroupDocs.Comparison for .NET 26.10 Release Notes

GroupDocs.Comparison version 26.10 introduces OCR-based image comparison — images are now compared by the text recognized in them rather than by their pixels, with both a Side-by-Side and a plain-text result layout. The release also brings a large set of spreadsheet comparison fixes — including a major performance improvement for XLSX files and correct row alignment, row heights and numeric cell types — along with improvements to PDF, Word, TXT and HTML preview output.

Full list of changes in this release

Major Features

Compare images by recognized text (OCR)

GroupDocs.Comparison can now compare images by the text recognized in them instead of by their pixels. Previously, comparing two images meant comparing them pixel by pixel — a scan shifted by a few pixels, re-saved at a different quality or produced by a different scanner reported differences everywhere. With OCR comparison enabled, the text is recognized on both images first and then compared as text, so the result shows the actual wording that changed.

This makes it possible to compare scanned contracts, screenshots, photographed documents and other image-only files in a meaningful way.

New public API

A new OcrOptions class has been added to the GroupDocs.Comparison.Options namespace and is exposed through the new CompareOptions.Ocr property.

The new OcrDisplayMode enum controls how the result of comparing the recognized text is laid out:

Usage

using (Comparer comparer = new Comparer("source.png"))
{
    var options = new CompareOptions
    {
        Ocr = new OcrOptions
        {
            Enabled = true,
            DisplayMode = OcrDisplayMode.SideBySide
        },
        GenerateSummaryPage = false
    };

    comparer.Add("target.png");
    var result = comparer.Compare("result.png", options);
}

To get a plain-text result instead of the preserved original layout, set DisplayMode to OcrDisplayMode.Text. To recognize a language other than the Latin script, set Language — and optionally point ResourcesPath at a folder with pre-downloaded models when the machine has no internet access:

using (Comparer comparer = new Comparer("source.png"))
{
    var options = new CompareOptions
    {
        Ocr = new OcrOptions
        {
            Enabled = true,
            DisplayMode = OcrDisplayMode.Text,
            Language = OcrLanguage.Cyrillic,
            ResourcesPath = @"C:\ocr-models",
            DisableResourceDownloads = true
        },
        GenerateSummaryPage = false
    };

    comparer.Add("target.png");
    comparer.Compare("result.png", options);
}

Support HighlightColor in StyleSettings for spreadsheet comparison

The HighlightColor property of StyleSettings is now applied when comparing spreadsheets, so the background color used to mark changed cells can be customized the same way as for other formats:

using (Comparer comparer = new Comparer("source.xlsx"))
{
    comparer.Add("target.xlsx");

    var options = new CompareOptions
    {
        InsertedItemStyle = new StyleSettings { HighlightColor = Color.LightGreen },
        DeletedItemStyle  = new StyleSettings { HighlightColor = Color.LightPink }
    };

    comparer.Compare("result.xlsx", options);
}

Improvements

• XLSX comparison takes minutes even for identical files — comparison of large XLSX files was disproportionately slow, taking minutes even when the documents were identical. The bottleneck has been removed and such comparisons now complete quickly. This improvement also affects not identical excel files.