我一直在使用这种方法将上传的.JPG
图像的大小调整为最大宽度,但这会导致图像以 kb 为单位大于源图像。 我做错了什么? 保存新图像时还需要执行其他操作吗?
我尝试了各种PixelFormat
组合,例如 PixelFormat.Format16bppRgb555
例如:源图像是 1900w .JPG
,试图调整为 1200w...
- 源文件为 563KB,
- 调整大小的文件为926KB或更大,甚至1.9MB
public static void ResizeToMaxWidth(string fileName, int maxWidth)
{
Image image = Image.FromFile(fileName);
if (image.Width > maxWidth)
{
double ratio = ((double)image.Width / (double)image.Height);
int newHeight = (int)Math.Round(Double.Parse((maxWidth / ratio).ToString()));
Bitmap resizedImage = new Bitmap(maxWidth, newHeight);
Graphics graphics = Graphics.FromImage(resizedImage);
graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
graphics.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High
Rectangle rectDestination = new Rectangle(0, 0, maxWidth, newHeight);
graphics.DrawImage(image, rectDestination, 0, 0, image.Width, image.Height, GraphicsUnit.Pixel);
graphics.Dispose();
image.Dispose();
resizedImage.Save(fileName);
resizedImage.Dispose();
}
image.Dispose();
}
您需要指定要将其另存为 jpeg 格式:
resizedImage.Save(fileName, System.Drawing.Imaging.ImageFormat.Jpeg);
否则它将默认保存为 BMP/PNG(我不记得是哪个了(。