Compare image in picture-box to default image

Question

I assigned Picturebox.Image to Default image. But It still pass the If-statement and open new Diaglog. I don't know why? Please help me!

private void saveBtn_Click(object sender, EventArgs e)
{
    if (imgBox.Image == Properties.Resources.DefaultImage || imgBox.Image == Properties.Resources.EmptyPhoto)
    {
        MessageBox.Show("Warning! Cannot save this image!");
    }
    else
    {
        SaveNoti save = new SaveNoti();
        save.sender = new SaveNoti.SEND(Task_functions);
        save.ShowDialog();
    }
}

Answer 1

Because each time you read the image from resources you get a new copy and then == will return false (because it obviously compares by reference). If you will ever use bitmaps from resources in GDI+ graphics...you'd better remember this.

Save them somewhere:

static readonly Image DefaultImage = Properties.Resources.DefaultImage;
static readonly Image EmptyPhone = Property.Resources.EmptyPhoto;

Then be sure to always use them to assign imgBox.Image property (where you assign the default value):

imgBox.Image = DefaultImage; // Do not use Properties.Resources.DefaultImage

Now you can check for equality (inside the click handler):

if (imgBox.Image == DefaultImage || imgBox.Image == EmptyPhoto)
{
    MessageBox.Show("Warning! Cannot save this image!");
}

If you use it more than once just extract a method:

private bool IsDefaultImage
    => imgBox.Image == DefaultImage || imgBox.Image == EmptyPhoto;