Return 降低质量后来自函数的位图图像

Question

我从网上找到这个功能。将图像的大小减小到 50%。现在我无法 return 下面的位图图像形式功能。

我找不到任何方法将当前位图图像放大到 50% 并且 return 它。

我需要创建一个内存流然后保存在那里吗？

//reduce Image size
public void ReduceImageSize(Bitmap bmp1)
{
    var jgpEncoder = GetEncoder(ImageFormat.Jpeg);
    // Create an Encoder object based on the GUID 
    // for the Quality parameter category.
    var myEncoder = Encoder.Quality;
    // Create an EncoderParameters object. 
    // An EncoderParameters object has an array of EncoderParameter 
    // objects. In this case, there is only one 
    // EncoderParameter object in the array.
    var myEncoderParameters = new EncoderParameters(1);

    var myEncoderParameter = new EncoderParameter(myEncoder, 50L);
    myEncoderParameters.Param[0] = myEncoderParameter;
    //rather than saving it should set to the current bitmap image.
    //bmp1.Save(@"c:\TestPhoto\TestPhotoQualityFifty.jpg", jgpEncoder, myEncoderParameters);


}
private static ImageCodecInfo GetEncoder(ImageFormat format)
{
    var codecs = ImageCodecInfo.GetImageDecoders();
    foreach (var codec in codecs)
    {
        if (codec.FormatID == format.Guid)
        {
            return codec;
        }
    }
    return null;
}
}

Answer 1

您应该只将文件保存到内存中，然后从该内存构建一个新图像：

using(var ram = new MemoryStream())
{
    bmp1.Save(ram, jgpEncoder, myEncoderParameters);
    ram.Seek(0, SeekOrigin.Begin); // reset stream to start so it can be read again
    return new Bitmap(ram);
}

Return 降低质量后来自函数的位图图像

Return Bitmap image from function after decreasing quality

c#

bitmapimage