将图像转换为像素格式-c#

我对下面的代码有问题。我能够将图像转换成我想要的像素格式。但问题是，当我为我的picturebox使用位图时，它只是黑色的

sourceImage = new Bitmap(sourceImage.Width, sourceImage.Height,
System.Drawing.Imaging.PixelFormat.Format24bppRgb);

pictureBoxCurrency.Image = sourceImage;

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您已经创建了新位图，但需要将图像从原始位图绘制（传输）到新位图

Bitmap newBitmap = new Bitmap(sourceImage.Size.Width, sourceImage.Size.Height, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
Graphics g = Graphics.FromImage(newBitmap);
g.DrawImage(sourceImage, new Point(0, 0));
g.Dispose();

pictureBoxCurrency.Image = sourceImage;