Pointers in VB using the Marshal or any otherway

private unsafe void PutImage(ref System.IntPtr pPtr, int imageBufferSize, ADVANTAGELib.AdvImageType imageType)
{
    byte** ppResBuffer = (byte**)pPtr;
    byte* pResBuffer = *ppResBuffer;
     
    int lPictureWidth = this.signatureImagePictureBox.Width;
    int lPictureHeight = this.signatureImagePictureBox.Height;
     
    using (MemoryStream imageStream = new MemoryStream(imageBufferSize))
    {
        using (BinaryWriter w = new BinaryWriter(imageStream))
        {
            for (int i = 0; i < imageBufferSize; i++)
            {
                w.Write((byte)pResBuffer[i]);
            }
             
            Bitmap lPicture = new Bitmap(Image.FromStream(imageStream), lPictureWidth, lPictureHeight);
             
            if (imageType == ADVANTAGELib.AdvImageType.AdvSignatureImage)
            {
                this.signatureImagePictureBox.Image = lPicture;
            }
            else
            {
                this.cardholderImagePictureBox.Image = lPicture;
            }
             
            System.Runtime.InteropServices.Marshal.FreeCoTaskMem((System.IntPtr)pResBuffer);
        }
    }
     
    System.GC.Collect();
}