Question

当我使用下面的代码将位图从8bpp转换为24bpp时，结果图像被移位但我无法弄清楚原因，有人可以帮忙吗？

private static Bitmap ConvertTo24(Bitmap bmpIn)
{
    bmpIn.Save(@"F:\sara1.bmp");
    Bitmap converted = new Bitmap(bmpIn.Width, bmpIn.Height, PixelFormat.Format24bppRgb);
    using (Graphics g = Graphics.FromImage(converted))
    {
         // Prevent DPI conversion
         g.PageUnit = GraphicsUnit.Pixel;
         // Draw the image
         g.DrawImageUnscaled(bmpIn, 0, 0);
         // g.DrawImage(bmpIn, 0, 0);
    }
    converted.Save(@"F:\sara2.bmp");
}

enter image description here

Answer 1

以下代码对我有用：

private static Bitmap ConvertTo24(Bitmap bmpIn)
{
    bmpIn.Save(@"F:\sara1.bmp");
    Bitmap converted = new Bitmap(bmpIn.Width, bmpIn.Height, PixelFormat.Format24bppRgb);
    using (Graphics g = Graphics.FromImage(converted))
    {
        // Prevent DPI conversion
        g.PageUnit = GraphicsUnit.Pixel;
        // Draw the image
        // g.DrawImageUnscaled(bmpIn, 0, 0);
        g.DrawImage(bmpIn, 0, 0, converted.Width, converted.Height);
    }
    converted.Save(@"F:\sara2.bmp");
}

提供宽度和高度可以重新调整图像。

Answer 2

在您的功能中收到问题之前，bmpIn可能会遇到问题。将8bpp图像放入f:\sara1.bmp之后，您可以测试以下（更好）代码（只是为了确保在转换前没有移动8bpp图像）。

private static Bitmap ConvertTo24(Bitmap bmpIn)
{
    //Bitmap bmpIn;
    bmpIn = new Bitmap(@"f:\sara1.bmp");
    Bitmap converted = new Bitmap(bmpIn.Width, bmpIn.Height, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
    using (Graphics g = Graphics.FromImage(converted))
    {
         g.PageUnit = GraphicsUnit.Pixel;
         Rectangle rng = new Rectangle(new Point(0, 0), bmpIn.Size);
         g.DrawImage(bmpIn, rng);  // use this instead of following
    }
    converted.Save(@"F:\sara2.bmp");
}

希望它工作正常4你。我在评论中已经使用了DrawImage（Image img，Rectangle rng）

答案已经完成。以下是解释。您的代码（已编辑。按原样使用并按照注释）

private static Bitmap ConvertTo24(Bitmap bmpIn)
{
    bmpIn.Save(@"F:\sara1.bmp");
    return;
    // After you have called this function. Go open your image f:\sara1.bmp from
    //hrad disk-- I doubt you would find it shifted here even before conversion
    Bitmap converted = new Bitmap(bmpIn.Width, bmpIn.Height, PixelFormat.Format24bppRgb);
    using (Graphics g = Graphics.FromImage(converted))
    {
         // Prevent DPI conversion
         g.PageUnit = GraphicsUnit.Pixel;
         // Draw the image
         g.DrawImageUnscaled(bmpIn, 0, 0);
         // g.DrawImage(bmpIn, 0, 0);
    }
    converted.Save(@"F:\sara2.bmp");
}

再次你的代码（我只是忽略你收到的8bpp Bitmap并直接从f驱动器中获取它，假设你在运行应用程序之前或者至少在调用此函数之前将其放入）

以下代码也适合我。

private static Bitmap ConvertTo24(Bitmap bmpIn)
{
    Bitmap bmpIn = new Bitmap(@"f:\sara1.bmp");
    Bitmap converted = new Bitmap(bmpIn.Width, bmpIn.Height, PixelFormat.Format24bppRgb);
    using (Graphics g = Graphics.FromImage(converted))
    {
         // Prevent DPI conversion
         g.PageUnit = GraphicsUnit.Pixel;
         // Draw the image
         g.DrawImageUnscaled(bmpIn, 0, 0);
         // g.DrawImage(bmpIn, 0, 0);
    }
    converted.Save(@"F:\sara2.bmp");
}

将8bpp转换为24bpp时，图像会移位

2 个答案: