创建缩略图并缩小图像大小

Question

我有非常大的图像(jpg),我想写一个csharp程序来循环文件,并将每个图像的大小减少75%.

我试过这个:

Image thumbNail = image.GetThumbnailImage(800, 600, null, new IntPtr());

但文件大小仍然很大.

反正有没有创建缩略图并且文件大小更小？

Answer 1

private void CompressAndSaveImage(Image img, string fileName, 
        long quality) {
    EncoderParameters parameters = new EncoderParameters(1);
    parameters.Param[0] = new EncoderParameter(Encoder.Quality, quality);
    img.Save(fileName, GetCodecInfo("image/jpeg"), parameters);
}

private static ImageCodecInfo GetCodecInfo(string mimeType) {
    foreach (ImageCodecInfo encoder in ImageCodecInfo.GetImageEncoders())
        if (encoder.MimeType == mimeType)
            return encoder;
    throw new ArgumentOutOfRangeException(
        string.Format("'{0}' not supported", mimeType));
}

用法:

Image myImg = Image.FromFile(@"C:\Test.jpg");
CompressAndSaveImage(myImg, @"C:\Test2.jpg", 10);

这将压缩Test.jpg的质量为10并将其保存为Test2.jpg.

编辑:作为一种扩展方法可能会更好:

private static void SaveCompressed(this Image img, string fileName, 
        long quality) {
    EncoderParameters parameters = new EncoderParameters(1);
    parameters.Param[0] = new EncoderParameter(Encoder.Quality, quality);
    img.Save(fileName, GetCodecInfo("image/jpeg"), parameters);
}

用法:

Image myImg = Image.FromFile(@"C:\Test.jpg");
myImg.SaveCompressed(@"C:\Test2.jpg", 10);