How to Merge Images and Add Borders or Labels Using .NET

Adding borders and captions to merged images improves clarity and professionalism—essential for technical reports, galleries, and marketing materials. Aspose.Imaging for .NET makes this easy to automate for any batch or scenario.

Real-World Problem

Simply merging images can lead to visual confusion, especially in galleries or side-by-side comparisons. Borders separate images clearly, while labels provide context, dates, or product info.

Solution Overview

Aspose.Imaging’s Graphics API lets you draw borders, fill backgrounds, and overlay text on any image during merge—scalable for any batch, style, or automation need.

Prerequisites

1. Visual Studio 2019 or later
2. .NET 6.0 or later (or .NET Framework 4.6.2+)
3. Aspose.Imaging for .NET from NuGet
4. Images to merge and annotate (any format)

PM> Install-Package Aspose.Imaging

Step-by-Step Implementation

bool mergeHorizontal = true; // or false for vertical
string[] files = Directory.GetFiles("./input", "*.jpg");

var images = files.Select(f => Image.Load(f)).ToList();
int borderThickness = 5;
Color borderColor = Color.Black;
Font labelFont = new Font("Arial", 24, FontStyle.Bold);
Color labelColor = Color.Blue;
string[] labels = files.Select(Path.GetFileNameWithoutExtension).ToArray();

int labelHeight = 40;
int totalWidth = mergeHorizontal ? images.Sum(i => i.Width + borderThickness * 2) : images.Max(i => i.Width) + borderThickness * 2;
int totalHeight = mergeHorizontal ? images.Max(i => i.Height) + borderThickness * 2 + labelHeight : images.Sum(i => i.Height + borderThickness * 2 + labelHeight);

using (var outImg = Image.Create(new PngOptions(), totalWidth, totalHeight))
{
    var graphics = new Aspose.Imaging.Graphics(outImg);
    graphics.Clear(Color.White);
    int x = 0, y = 0;
    for (int i = 0; i < images.Count; i++)
    {
        var img = images[i];
        int drawX = mergeHorizontal ? x : (totalWidth - img.Width) / 2;
        int drawY = mergeHorizontal ? (totalHeight - img.Height - labelHeight) / 2 : y;
        // Draw border
        graphics.DrawRectangle(new Pen(borderColor, borderThickness), drawX - borderThickness, drawY - borderThickness, img.Width + borderThickness * 2, img.Height + borderThickness * 2);
        // Draw image
        graphics.DrawImage(img, drawX, drawY, img.Width, img.Height);
        // Draw label
        graphics.DrawString(labels[i], labelFont, new SolidBrush(labelColor), drawX, drawY + img.Height + 5);
        if (mergeHorizontal)
            x += img.Width + borderThickness * 2;
        else
            y += img.Height + borderThickness * 2 + labelHeight;
    }
    outImg.Save("./output/merged_with_borders_labels.png");
}
images.ForEach(img => img.Dispose());

Use Cases and Applications

• Marketing and social media collages with product names
• Technical documentation and reports with figure captions
• Annotated photo walls for events or exhibitions
• E-commerce product comparison charts

Common Challenges and Solutions

Challenge 1: Labels Overlap Images or Borders

Solution: Increase labelHeight or adjust text position as needed.

Challenge 2: Borders Cover Image Content

Solution: Draw borders outside the image area (as in sample code).

Challenge 3: Font or Color Issues

Solution: Choose web-safe fonts and high-contrast label colors for readability.

Performance Considerations

• Dispose all images after drawing to avoid memory leaks
• Use PNG for clear borders and lossless quality; JPEG for web
• Test batch size and canvas size for large collages

Best Practices

1. Keep border and label styles consistent for branding
2. Preview output in the target app or platform
3. Automate for dynamic folders or product lists
4. Store or export source settings for repeat runs

Advanced Scenarios

Scenario 1: Custom Borders Per Image

Draw different colors/thickness for each photo or category.

Scenario 2: Rotated or Diagonal Labels

Use Graphics transformations for creative styles.

FAQ

Q: Can I use transparent or rounded borders? A: Yes, draw with semi-transparent colors or round rectangles for effect.

Q: How do I localize/caption in multiple languages? A: Use a translation API to generate labels[] before drawing.

Q: Can I automate label content? A: Yes, pull from file metadata, EXIF, or a database for dynamic labeling.

Conclusion

With Aspose.Imaging for .NET, it’s easy to create annotated, visually distinct merged images—automated for any workflow, from galleries to technical docs.

See Aspose.Imaging for .NET API Reference for more customization with borders, labels, and drawing.