Converting bitmap to grayscale

luci marginean

I want to convert an image from bitmap to grayscale, but when I load it in a picturebox...not on a button click event...
Like this...I load a bitmap picture and in the picturebox and it appears directly as a grayscale picture...
I found some source code on the Internet, but I don't really kmow how where to put the code to do what I want...
Thank you

3 Replies

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Frogleg15y ago
Accepted answer

Bitmap bmp;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
// loadImage();//use this to autoload
}
public void loadImage()
{
Image img = Image.FromFile("po.bmp");
bmp = new Bitmap(img.Width, img.Height);
Graphics g = Graphics.FromImage(bmp);
g.DrawImage(img, 0, 0);
pictureBox1.Image = ConvertToGrayscale(bmp);
}

public Bitmap ConvertToGrayscale(Bitmap source)
{
Bitmap bm = new Bitmap(source.Width, source.Height);
for (int y = 0; y < bm.Height; y++)
{
for (int x = 0; x < bm.Width; x++)
{
Color c = source.GetPixel(x, y);
int luma = (int)(c.R * 0.3 + c.G * 0.59 + c.B * 0.11);
bm.SetPixel(x, y, Color.FromArgb(luma, luma, luma));
}
}
return bm;
}
private void button1_Click(object sender, EventArgs e)
{
loadImage();
}
Try this. To load automatically uncomment
// loadImage();//use this to autoload
or put loadImage(); in open file dialog
0
Kip Hackman5y ago
You can use LEADTOOLS Imaging Pro SDK technology in your application.
https://www.leadtools.com/sdk/image-processing
You can leverage the GrayscaleCommand class to convert an image to a grayscale image.
Here is some sample code:
using (RasterCodecs codecs = new RasterCodecs())
{
    string srcFileName = @"FILE PATH TO INPUT IMAGE";
    string destFileName = @"FILE PATH TO OUTPUT GRAYSCALE IMAGE";
    using (RasterImage image = codecs.Load(srcFileName, 24, CodecsLoadByteOrder.Bgr, 1, 1))
    {
        // Convert to 8-bit grayscale
        GrayscaleCommand command = new GrayscaleCommand();
        command.BitsPerPixel = 8;
        command.Run(image);

        codecs.Options.Jpeg.Save.QualityFactor = 2;
        codecs.Save(image, destFileName, RasterImageFormat.Jpeg, 8);
    }
}
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luci marginean15y ago
Thank you verry much for you help...but I managed to make the program working last night...

private void btnLoad_Click(object sender, EventArgs e)
        {
            OpenFileDialog fDialog = new OpenFileDialog();

            fDialog.Filter =
                "Bitmaps |*.bmp| GIFs |*.gif| JPEGs |*.jpg;*.jpeg| TIFs |*.tif";

            fDialog.InitialDirectory = @"C:\Documents and Settings\Taticu\Desktop\Scoala\Poze proba";

            if (fDialog.ShowDialog() == DialogResult.OK)
            {
                Image old = Image.FromFile(fDialog.FileName);
                pcbImage.Image = (Image)Grayscale(new Bitmap(old));
                pcbImage.SizeMode = PictureBoxSizeMode.AutoSize;
            }

        }

public static Bitmap Grayscale(Bitmap original)
        {

            Bitmap newBitmap = new Bitmap(original.Width, original.Height);
            Graphics g = Graphics.FromImage(newBitmap);
            ColorMatrix colorMatrix = new ColorMatrix(
               new float[][]
              {
                 new float[] {.3f, .3f, .3f, 0, 0},
                 new float[] {.59f, .59f, .59f, 0, 0},
                 new float[] {.11f, .11f, .11f, 0, 0},
                 new float[] {0, 0, 0, 1, 0},
                 new float[] {0, 0, 0, 0, 1}
              });

            ImageAttributes attributes = new ImageAttributes();

            attributes.SetColorMatrix(colorMatrix);

            g.DrawImage(original, new Rectangle(0, 0, original.Width, original.Height),
               0, 0, original.Width, original.Height, GraphicsUnit.Pixel, attributes);

            g.Dispose();
            return newBitmap;
        }
0