Question

在我的项目中，我必须通过输入百分比来减少C＃程序的图像大小。

然而，有些不对劲：

图片格式： TIF

原始图片 6MB，1920 * 1080

已调整大小的图片：27KB，含1728 * 972

缩小至 90％

它不是27KB，而是＆gt; 5MB ...

代码

    public Image reduce(Image sourceImage, string size)
    {
        var original = sourceImage;
        //store image widths in variable for easier use
        var oW = (decimal)original.Width;
        var oH = (decimal)original.Height;
        var dW = (decimal)desiredWidth;
        var dH = (decimal)desiredHeight;
        var dR = (decimal)Int32.Parse(size);;

        var nH = oH * (dR / 100); 
        var nW = oW * (dR / 100);

        var resized = new Bitmap((int)nW, (int)nH);
        using (Graphics gr = Graphics.FromImage(sourceImage))
        {
            gr.SmoothingMode = SmoothingMode.HighQuality;
            gr.InterpolationMode = InterpolationMode.HighQualityBicubic;
            gr.PixelOffsetMode = PixelOffsetMode.HighQuality;
            gr.DrawImage(resized, new Rectangle(0, 0, (int)nH, (int)nW));
        }

        return resized;
    }

任何想法？

更新

              Image nImage = imagetool.reduce(originalImg, size);

              byte[] nImageData = imagetool.imageToByteArray(nImage);

              int nImageSize = nImageData.Length;
              Console.WriteLine("new image size " + nImageSize );


               try
               {
                  Console.WriteLine("trying to update the image in sharepoint");

                  web.Files.Add(Path.Combine(itemsite, itemSubsite, fileURL), nImageData, true);
               }

更新2

    public byte[] imageToByteArray(Image imageIn)
    {
        using (var ms = new MemoryStream())
        {
            if (imageIn.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Jpeg))
            {
                imageIn.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
                return ms.ToArray();
            }
            if (imageIn.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Png))
            {
                imageIn.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
                return ms.ToArray();
            }
            if (imageIn.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Bmp))
            {
                imageIn.Save(ms, System.Drawing.Imaging.ImageFormat.Bmp);
                return ms.ToArray();
            }
            if (imageIn.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Gif))
            {
                imageIn.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
                return ms.ToArray();
            }
            if (imageIn.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Tiff))
            {
                imageIn.Save(ms, System.Drawing.Imaging.ImageFormat.Tiff);
                return ms.ToArray();
            }
            else
            {
                imageIn.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
                return ms.ToArray();
            }
        }
    }

Answer 1

在其他地方创建

nImage

，其格式不是TIFF，代码完成于：

var resized = new Bitmap((int)nW, (int)nH)

Answer 2

您的新图片没有任何格式，当您创建新的Bitmap对象时，它不会自动从您的原始图片中读取，因此被写为jpg，（来自最终{{1}你的部分代码）

解决此问题的方法是将原始格式转换为else，并在将新图像写入imageToByteArray时使用该格式。您也可以取消长MemoryStream块

if..else

您的主叫代码应为

public byte[] imageToByteArray(Image imageIn, ImageFormat format)
{
    using(var ms = new MemoryStream())
    {
        imageIn.Save(ms,format);
        return ms.ToArray();
    }
 }

调整图像大小，减少C＃的损失

2 个答案: