public PngImage(
	RasterImage rasterImage,
	PngColorType colorType
)

Public Sub New ( 
	rasterImage As RasterImage,
	colorType As PngColorType
)

public:
PngImage(
	RasterImage^ rasterImage, 
	PngColorType colorType
)

new : 
        rasterImage : RasterImage * 
        colorType : PngColorType -> PngImage

[C#]

string dir = "c:\\temp\\";

// Load a grayscale PNG image from a colored BMP image.
// First, create a temporal BMP image that will be a foundation for building a PNG image.
// You can also load BMP image from a file or use an image of any other raster format.
using (Aspose.Imaging.FileFormats.Bmp.BmpImage bmpImage = new Aspose.Imaging.FileFormats.Bmp.BmpImage(100, 100))
{
    // Fill the entire BMP image in red.
    Aspose.Imaging.Graphics gr = new Aspose.Imaging.Graphics(bmpImage);
    Aspose.Imaging.Brushes.SolidBrush brush = new Aspose.Imaging.Brushes.SolidBrush(Aspose.Imaging.Color.Red);
    gr.FillRectangle(brush, bmpImage.Bounds);

    // The colors of the image pixels will be converted to their grayscale counterparts.
    using (Aspose.Imaging.FileFormats.Png.PngImage pngImage = new Aspose.Imaging.FileFormats.Png.PngImage(bmpImage, Aspose.Imaging.FileFormats.Png.PngColorType.Grayscale))
    {
        pngImage.Save(dir + "output.grayscale.png");
    }
}