[C#] GrayScale (by ColorMatrix) causes OutOfMemoryException. Why ?

Question

I have 2 forms, A and B. On the Form A, I click a button and an Image is being loaded to a PictureBox located ona the Form B. And, I want to set GrayScale to this image by:

   public void SetGrayScale(PictureBox pb)
    {
        ColorMatrix matrix = new ColorMatrix(new float[][]
        {
            new float[] {0.299f, 0.299f, 0.299f, 0, 0},
            new float[] {0.587f, 0.587f, 0.587f, 0, 0},
            new float[] {0.114f, 0.114f, 0.114f, 0, 0},
            new float[] {     0,      0,      0, 1, 0},
            new float[] {     0,      0,      0, 0, 0}
        });

        Image image = (Bitmap)pb.Image.Clone();

        ImageAttributes attributes = new ImageAttributes();
        attributes.SetColorMatrix(matrix);

        Graphics graphics = Graphics.FromImage(image);

        graphics.DrawImage(image,
                            new Rectangle(0, 0, image.Width, image.Height),
                            0,
                            0,
                            image.Width,
                            image.Height,
                            GraphicsUnit.Pixel,
                            attributes);

        graphics.Dispose();

        pb.Image = image;
    }

This code works properly when the PictureBox is on the same form (A). But, when it is on the Form B, the OutOfMemoryException is raised. Why ?

Answer 1

The image isn't big - 260x110px

The error is here :

Graphics graphics = Graphics.FromImage(image);

Answer 2

More questions/things for you to investigate rather than an actual answer I'm afraid:

1. As in the comment to your answer - is the Image object correct?

2. If not then that implies that there's something wrong with the PictureBox object passed into this method, or that you can't access the PictureBox's Image properly.

My first thought was threading, but both forms should be in the UI thread.

Answer 3

Ok, I've Fixed it :) The solution is, I had to created a Bitmap object from the OpenDialog.FileName, and later set PictureBox.Image = myBitmap

I didn't do it at the beginning, I was just setting PictureBox.Load(OpenDialog.FileName). And that was my mistake.

Ok, thank's for Your cooperation, ChrisF ! :)