[.Net]高畫質縮圖(Winform)－Programer達

原本使用Image.GetThumbnailImage來做縮圖，結果畫質相當差，模糊不清，所以改用Graphics重繪

Graphics物件重繪圖片的畫質會比Image.GetThumbnailImage來的好

以下為參考程式碼

//讀取圖檔
Image inputImage = Image.FromStream(new MemoryStream(File.ReadAllBytes("圖檔來源")));
//縮圖，此處縮圖大小為800x600
Bitmap thumbnailBitmap = new Bitmap(800, 600);
Graphics thumbnailGraph = Graphics.FromImage(thumbnailBitmap);
//這三個屬性設定圖片品質
thumbnailGraph.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
thumbnailGraph.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
thumbnailGraph.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
//重繪圖片
Rectangle imageRectangle = new Rectangle(0, 0, 800, 600);
thumbnailGraph.DrawImage(inputImage, imageRectangle);
//存檔
thumbnailBitmap.Save(savePath + Path.GetFileName(file), inputImage.RawFormat);
//釋放資源
thumbnailGraph.Dispose();
thumbnailBitmap.Dispose();
inputImage.Dispose();
GC.Collect();

參考資源：
1. ＭＳＤＮ
2.http://sweeteason.pixnet.net/blog/post/31925002-%E8%87%AA%E5%B7%B1%E7%AD%86%E8%A8%98---asp.net-%E5%9C%96%E7%89%87%E5%8B%95%E6%85%8B%E7%B8%AE%E5%9C%96-(%E9%AB%98%E7%95%AB%E8%B3%AA%E7%BA%8C%E7%AF%87)