在C＃中調整圖像大小而不會降低質量

Question

static Image ScaleImage(Image image, int Width, int Height)
{
        int originalWidth = image.Width;
        int originalHeight = image.Height;

        double ratioX = (double)Width / (double)originalWidth;
        double ratioY = (double)Height / (double)originalHeight;
        double ratio = Math.Min(ratioX, ratioY);

        int newHeight = (int)(originalHeight * ratio);
        int newWidth = (int)(originalWidth * ratio);

        Image scaledImage = new Bitmap(newWidth, newHeight);
        Graphics graphic = Graphics.FromImage(scaledImage);

        graphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
        graphic.SmoothingMode = SmoothingMode.HighQuality;
        graphic.PixelOffsetMode = PixelOffsetMode.HighQuality;
        graphic.CompositingQuality = CompositingQuality.HighQuality;

        graphic.Clear(Color.Transparent);
        graphic.DrawImage(image, 0, 0, newWidth, newHeight);

        return scaledImage;
}

        Image full = new Bitmap("img.png");
        Image scaledImage = ScaleImage(full, full.Width / 2, full.Height / 2);
        Clipboard.SetImage(scaledImage); 

問題在於，使用此代碼調整大小后，圖像有點模糊。

我想將原始圖像的一個版本復制到剪貼板，但是要縮放（縮小2/3倍），如果我將圖像粘貼到某個地方並手動調整大小（以更高的分辨率），則我希望獲得與原始圖像相同的質量。

我怎樣才能做到這一點？

Answer 1

試試這個代碼，它幾乎就像您的代碼，但是我在自己的圖片查看器中使用它，卻看不到任何“模糊”。

它不會調整每一側的大小，而是將圖片與MaxImageSizeToResize一側放置在正方形中並保存比例。 可能是由於未按比例調整大小而導致模糊或丟失了某些屬性。

嘗試說-結果是否相同。

public static System.Drawing.Bitmap Resize(string pathToOriginalFile, int MaxImageSizeToResize)
    {
        using (var image = System.Drawing.Image.FromFile(pathToOriginalFile))
        {
            return LocalGet(image);
        }

        System.Drawing.Bitmap LocalGet(System.Drawing.Image image)
        {
            int rW = 0;
            int rH = 0;

            double c = 0;
            c = ((double)image.Height / (double)MaxImageSizeToResize);
            rW = (int)(image.Width / c);
            rH = MaxImageSizeToResize;

            var destRect = new System.Drawing.Rectangle(0, 0, rW, rH);
            var destImage = new System.Drawing.Bitmap(rW, rH);

            destImage.SetResolution(image.HorizontalResolution, image.VerticalResolution);

            using (var graphics = System.Drawing.Graphics.FromImage(destImage))
            {
                graphics.CompositingMode = CompositingMode.SourceCopy;
                graphics.CompositingQuality = CompositingQuality.HighQuality;
                graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
                graphics.SmoothingMode = SmoothingMode.HighQuality;
                graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;

                using (var wrapMode = new System.Drawing.Imaging.ImageAttributes())
                {
                    wrapMode.SetWrapMode(WrapMode.TileFlipXY);
                    graphics.DrawImage(image, destRect, 0, 0, image.Width, image.Height, System.Drawing.GraphicsUnit.Pixel, wrapMode);
                }
            }

            return destImage;
        }
    }