Nager.FileCompress

Nager.FileCompress is a lightweight, efficient Windows Service designed to automatically scan directories for images and optimize their file size to save storage space.

The service processes images safely: it preserves original file metadata (creation/modification dates and EXIF data) and only replaces the original file if a significant storage reduction is achieved.

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Features

• Background Automation: Runs as a native Windows Service with zero user interaction required.
• Parallel Processing: Configurable degree of parallelism to optimize performance on multi-core systems.
• Smart Thresholding: Only overwrites the original file if a minimum of 20% space savings is achieved.
• Timestamp Preservation: Keeps the exact same Creation Date and Modification Date as the original file.
• Metadata Retention: Uses SixLabors.ImageSharp for processing, ensuring that all embedded EXIF data remains intact.
• Flexible Format Output: Supports conversion between image formats (e.g., converting to webp or maintaining jpeg) and custom quality settings.
• Safe Mode: Includes an AnalyzeOnly flag to simulate optimization and preview potential space savings without modifying files.

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Configuration

The service is configured via the appsettings.json file. You can define the target directory, file types to scan, and the operational mode.

{
  "Serilog": {
    "MinimumLevel": {
      "Default": "Information",
      "Override": {
        "Quartz": "Warning",
        "Microsoft.Hosting.Lifetime": "Information"
      }
    }
  },
  "FileProcessor": {
    "MaxDegreeOfParallelism": 4,
    "AnalyzeOnly": true,
    "SourceDirectory": "C:\\Temp\\TestImageData",
    "ImageOptimizer": {
      "FileExtensions": [
        ".jpg",
        ".jpeg"
      ],
      "Quality": 80,
      "OutputFormat": "jpeg",
      "DeleteOriginal": true
    }
  }
}

Configuration Options

Key	Type	Description
FileProcessor.MaxDegreeOfParallelism	int	Defines the maximum number of files processed in parallel.
FileProcessor.AnalyzeOnly	bool	If true, the service only calculates potential savings and logs them without modifying or deleting files. Set to false for active production optimization.
FileProcessor.SourceDirectory	string	The absolute path to the directory that should be scanned for images.
FileProcessor.ImageOptimizer.FileExtensions	string[]	An array of file extensions to include in the scan (e.g., [".jpg", ".jpeg"]).
FileProcessor.ImageOptimizer.Quality	int	The quality level for the optimized image (typically between 70 and 100).
FileProcessor.ImageOptimizer.OutputFormat	string	The target format for the optimized image. Supported options include jpeg and webp.
FileProcessor.ImageOptimizer.DeleteOriginal	bool	If true, the original file will be removed after a successful optimization/replacement.

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How it Works (Core Logic)

1. Scan: The service scans the SourceDirectory matching the SearchPattern.
2. Process: Images are loaded and optimized using ImageSharp.
3. Evaluate: The service calculates the compression ratio:

$$\text{Percent Saved} = 100 - \left( \frac{\text{Compressed Size}}{\text{Original Size}} \times 100 \right)$$

4. Apply: If $\text{Percent Saved} \ge 20\%$, the original file is replaced (unless AnalyzeOnly is true).
5. Sync Metadata: The Creation Time, Last Write Time (Modification Date), and EXIF data are explicitly copied from the original file onto the optimized file.

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Installation

1. Install as a Windows Service

Open Command Prompt (CMD) or PowerShell as Administrator and use the native Windows Service Control (sc.exe) tool to register the service:

sc.exe create "Nager.FileCompress" binpath= "C:\\Path\\To\\Your\\Published\\App\\Nager.FileCompressService.exe" start= auto

(Note: The space after binpath= and start= is strictly required by the sc command).

2. Start the Service

sc.exe start "Nager.FileCompress"

3. Uninstalling the Service

If you need to remove the service in the future, stop it first, then delete it:

sc.exe stop "Nager.FileCompress"
sc.exe delete "Nager.FileCompress"

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Prerequisites & Dependencies

• .NET 10.0 Runtime