如何调整图像大小而不会降低质量

我有一个高质量的大图像（根据我的需要），我需要调整到小尺寸（30 x 30px），我用graphic.DrawImage调整它的大小。 但是当我resize时，它会变得模糊不清。 我也尝试过CompositingQuality和InterpolationMode，但这一切都很糟糕。

例如，我正在尝试的质量。

我的结果

编辑图标的图像我画自己，也许它会更好地绘制它而不resize？

EDIT2

调整代码大小：

Bitmap tbmp; //drawing all my features in tbmp with graphics bmp = new Bitmap(width + 5, height + 5); bmp.MakeTransparent(Color.Black); using (var gg = Graphics.FromImage(bmp)) { gg.CompositingQuality = CompositingQuality.HighQuality; // gg.SmoothingMode = SmoothingMode.HighQuality; gg.InterpolationMode = InterpolationMode.HighQualityBicubic; gg.DrawImage(tbmp, new Rectangle(0, 0, width, height), new Rectangle(GXMin, GYMin, GXMax + 20, GYMax + 20), GraphicsUnit.Pixel); gg.Dispose(); } 

Answer 1

我使用此方法作为从原始（任何大小）获取缩略图（任何大小）的方法。 请注意，当您要求的尺寸比率与原始尺寸比率大不相同时，存在固有问题。 最好问一下彼此规模的尺寸：

 public static Image GetThumbnailImage(Image OriginalImage, Size ThumbSize) { Int32 thWidth = ThumbSize.Width; Int32 thHeight = ThumbSize.Height; Image i = OriginalImage; Int32 w = i.Width; Int32 h = i.Height; Int32 th = thWidth; Int32 tw = thWidth; if (h > w) { Double ratio = (Double)w / (Double)h; th = thHeight < h ? thHeight : h; tw = thWidth < w ? (Int32)(ratio * thWidth) : w; } else { Double ratio = (Double)h / (Double)w; th = thHeight < h ? (Int32)(ratio * thHeight) : h; tw = thWidth < w ? thWidth : w; } Bitmap target = new Bitmap(tw, th); Graphics g = Graphics.FromImage(target); g.SmoothingMode = SmoothingMode.HighQuality; g.CompositingQuality = CompositingQuality.HighQuality; g.InterpolationMode = InterpolationMode.High; Rectangle rect = new Rectangle(0, 0, tw, th); g.DrawImage(i, rect, 0, 0, w, h, GraphicsUnit.Pixel); return (Image)target; }