private void button3_Click(object sender, EventArgs e)
{
previewbox.Image = null;
richTextBox1.Text = "";
round_cb.Checked = false;
vignette_cb.Checked = false;
blur_cb.Checked = false;
pictureBox1.Image = null;
colorDialog1.Color = DEFAULT_TEXT_COLOR;
colorDialog_Vignette.Color = DEFAULT_VIGNETTE_COLOR;
try {
targerImg.Dispose();
} catch (Exception ex) { }
finally { }
targetpicture = null;
trackBar1.Value = DEFAULT_BLUR_VALUE;
trackBar2.Value = DEFALUT_ROUNDER_CORNER_VALUE;
}