C# – Convert transparent png in color to single color

bitmapctransparency

I am working with Bitmap C# and wondering how to convert a color png image to only one color. I want all the visible colors in the image to become white. The parts that are transparent should remain transparent. I am going to display these agains a grey background.

Best Answer

If the image doesn't use alpha channel for transparency then the following will do:

Bitmap image;

for (int x = 0; x < image.Width; x++)
{
    for (int y = 0; y < image.Height; y++)
    {
        if (image.GetPixel(x, y) != Color.Transparent)
        {
            image.SetPixel(x, y, Color.White);
        }
    }
}

Related Solutions

Android – Save bitmap to location

try (FileOutputStream out = new FileOutputStream(filename)) {
    bmp.compress(Bitmap.CompressFormat.PNG, 100, out); // bmp is your Bitmap instance
    // PNG is a lossless format, the compression factor (100) is ignored
} catch (IOException e) {
    e.printStackTrace();
}

C# – Transparent PNG in PictureBox

It is difficult to make a control that is partially transparent.

What you should do is handle the lower PictureBox's Paint event (the one that does not need to be transparent), and draw the overlay image using e.Graphics.DrawImage(image, x, y). This will draw transparent and semi-transparent images correctly.

EDIT: In response to your comment, there's nothing wrong with calling the Invalidate method in the MouseMove event. However, you will notice some flickering. To solve the flickering, make a control that inherits PictureBox, and call SetStyle(ControlStyles.DoubleBuffered, true) in the constructor.

Best Answer

Related Solutions

Android – Save bitmap to location

C# – Transparent PNG in PictureBox

Related Topic