C#创建缩略图(低质量和大尺寸问题)

Question

public void CreateThumbnail(Image img1, Photo photo, string targetDirectoryThumbs)
        {
            int newWidth = 700;
            int newHeight = 700;
            double ratio = 0;

            if (img1.Width > img1.Height)
            {
                ratio = img1.Width / (double)img1.Height;
                newHeight = (int)(newHeight / ratio);
            }
            else
            {
                ratio = img1.Height / (double)img1.Width;
                newWidth = (int)(newWidth / ratio);
            }

            Image bmp1 = img1.GetThumbnailImage(newWidth, newHeight, null, IntPtr.Zero);
            bmp1.Save(targetDirectoryThumbs + photo.PhotoID + ".jpg");

            img1.Dispose();
            bmp1.Dispose();
        }

我已经700px这样说,你可以更好地了解问题.这是原始图像和调整大小的图像.

有什么好建议吗？

谢谢,
Ile

Answer 1

您应该会发现我对此问题的回答很有帮助.它包含一个用于在C#中进行高质量图像缩放的示例.

我的另一个答案中的完整示例包括如何将图像保存为jpeg.

这是代码的相关部分......

    /// <summary> 
    /// Resize the image to the specified width and height. 
    /// </summary> 
    /// <param name="image">The image to resize.</param> 
    /// <param name="width">The width to resize to.</param> 
    /// <param name="height">The height to resize to.</param> 
    /// <returns>The resized image.</returns> 
    public static System.Drawing.Bitmap ResizeImage(System.Drawing.Image image, int width, int height) 
    { 
        //a holder for the result 
        Bitmap result = new Bitmap(width, height); 

        //use a graphics object to draw the resized image into the bitmap 
        using (Graphics graphics = Graphics.FromImage(result)) 
        { 
            //set the resize quality modes to high quality 
            graphics.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; 
            graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; 
            graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; 
            //draw the image into the target bitmap 
            graphics.DrawImage(image, 0, 0, result.Width, result.Height); 
        } 

        //return the resulting bitmap 
        return result; 
    }