Question

我正在尝试将png图像转换为gif和jpg格式。我正在使用在Microsoft documentation上找到的代码。

我通过将以下代码修改为git-hub example：

        public static void Main(string[] args)
        {
            // Load the image.
            using (Image png = Image.FromFile("test-image.png"))
            {
                var withBackground = SetWhiteBackground(png);
                // Save the image in JPEG format.
                withBackground.Save("test-image.jpg");

                // Save the image in GIF format.
                withBackground.Save("test-image.gif");
                withBackground.Dispose();
            }
        }

        private static Image SetWhiteBackground(Image img)
        {
            Bitmap imgWithBackground = new Bitmap(img.Width, img.Height);
            Rectangle rect = new Rectangle(Point.Empty, img.Size);
            using (Graphics g = Graphics.FromImage(imgWithBackground))
            {
                g.Clear(Color.White);
                g.DrawImageUnscaledAndClipped(img, rect);
            }

            return imgWithBackground;
        }

原始图像（虚构数据）是这样的：

当我将其转换为gif时，我得到了：

所以我的问题是：有没有办法使png的gif格式看起来一样？

编辑： Hans Passant 指出，根本问题是透明的背景。经过一番挖掘，我找到了答案here。我使用链接中提到的代码片段将背景设置为白色：

        private Image SetWhiteBackground(Image img)
        {
            Bitmap imgWithBackground = new Bitmap(img.Width, img.Height);
            Rectangle rect = new Rectangle(Point.Empty, img.Size);
            using (Graphics g = Graphics.FromImage(imgWithBackground))
            {
                g.Clear(Color.White);
                g.DrawImageUnscaledAndClipped(img, rect);
            }

            return imgWithBackground;
        }

所以现在gif看起来像这样：

Answer 1

类似（https://docs.sixlabors.com/articles/ImageSharp/GettingStarted.html）：

using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Processing;

// Open the file and detect the file type and decode it.
// Our image is now in an uncompressed, file format agnostic, structure in-memory as a series of pixels.
using (Image image = Image.Load("test-image.png")) 
{     
    // The library automatically picks an encoder based on the file extensions then encodes and write the data to disk.
    image.Save("test.gif"); 
}

将PNG转换为GIF或JPG

1 个答案: