Replace colors in an image

Color replacement helps you standardize image appearance across document workflows.

Use this workflow when you need to:

• Enforce brand color consistency
• Correct scanned images with unwanted color casts
• Replace specific source colors in bulk processing pipelines

Prepare the project

Register the SDK license before running image-processing operations. For setup details, refer to the getting started with .NET SDK guide.

using GdPicture14;

LicenseManager licence = new LicenseManager();
licence.RegisterKEY(""); // Set your license key

Load the source image

Create a GdPictureImaging instance and load the image:

using GdPictureImaging imaging = new GdPictureImaging();

// Load the image that contains colors to be replaced
int imageId = imaging.CreateGdPictureImageFromFile(@"input.png");

Replace colors

Run the color swap operation:

// Execute the color replacement operation
imaging.SwapColor(imageId, GdPicture14.Imaging.GdPictureColor.Black, GdPicture14.Imaging.GdPictureColor.Blue);

SwapColor replaces every pixel matching the source color (black) with the target color (blue).

Save the modified image

Write the processed image to PNG:

// Save the modified image with replaced colors
imaging.SaveAsPNG(imageId, @"output.png");

Conclusion

This workflow replaces selected colors in an image and saves a standardized output file.