0

我正在尝试调整通过 MVC3 应用上传的图像的大小。下面的代码能够根据指定的参数根据我的目标大小调整图像大小，但最终结果是颗粒状图像。我在 stackoverflow 和 msn 示例中尝试了很多不同的解决方案，但一切都返回了一个颗粒状的图像。

static public Image ResizeFile(HttpPostedFileBase file, int targeWidth, int targetHeight)
    {
        Image originalImage = null;
        bool IsImage = true;
        Bitmap bitmap = null;

        try
        {
            originalImage = Image.FromStream(file.InputStream, true, true);
        }
        catch
        {
            IsImage = false;
        }

        if (IsImage)
        {
            //accept an image only if it is less than 3mb(max)
            if (file.ContentLength <= 3145728)
            {
                var newImage = new MemoryStream();
                Rectangle origRect = new Rectangle(0, 0, originalImage.Width, originalImage.Height);

                // if targets are null, require scale. for specified sized images eg. Event Image, or Profile photos.
                int newWidth = 0;
                int newHeight = 0;

                //if the width is greater than height
                if (originalImage.Width > originalImage.Height)
                {
                    newWidth = targeWidth;
                    newHeight = targetHeight;
                    bitmap = new Bitmap(newWidth, newHeight);
                }

                //if the size of image is larger than either one of the target size
                else if (originalImage.Width > targeWidth || originalImage.Height > targetHeight)
                {
                    newWidth = targeWidth;
                    newHeight = targetHeight;
                    bitmap = new Bitmap(newWidth, newHeight);
                }
                //reuse old dimensions
                else
                {
                    bitmap = new Bitmap(originalImage.Width, originalImage.Height);
                }

                try
                {
                    using (Graphics g = Graphics.FromImage((Image)bitmap))
                    {
                        g.SmoothingMode = SmoothingMode.AntiAlias;
                        g.PixelOffsetMode = PixelOffsetMode.HighQuality;
                        g.CompositingQuality = CompositingQuality.HighQuality;
                        g.InterpolationMode = InterpolationMode.HighQualityBicubic;
                        g.DrawImage(originalImage, new Rectangle(0, 0, newWidth, newHeight),
                            0,
                            0,           // upper-left corner of source rectangle
                            originalImage.Width,       // width of source rectangle
                            originalImage.Height,      // height of source rectangle
                            GraphicsUnit.Pixel);
                        bitmap.Save(newImage, ImageFormat.Jpeg);
                    }
                }
                catch (Exception ex)
                {   // error before IDisposable ownership transfer
                    if (bitmap != null)
                        bitmap.Dispose();

                    logger.Info("Domain/Utilities/ImageResizer->ResizeFile: " + ex.ToString());

                    throw new Exception("Error resizing file.");
                }
            }                
        }

        return (Image)bitmap;
    }

UPDATE 1 删除了参数和编码器，目前保存在 .jpeg 中。但仍会产生颗粒状图像。

4

1 回答 1

0

几个建议

1）确保您没有放大图像。

2）尝试g.SmoothingMode = Drawing2D.SmoothingMode.AntiAlias而不是高质量

如果上述失败，我将删除除上述之外的所有其他选项设置，然后简单地使用保存文件；

bitmap.Save(newImage, Imaging.ImageFormat.Jpeg);

我发现上面的工作非常好。

于 2012-09-01T07:42:31.577 回答