从一个目录缩小.JPG图像并保存为另一个.JPG/.PNG

Question

因此，我在这里要做的是导入一个大尺寸的.JPG图像列表，我想将它们缩小而没有太多的质量损失，然后将它们输出为.JPG/.PNG以避免像.BMP那样占用太多内存。

我知道你只能在处理.bmp的时候处理图像。 下面是一些示例代码的我已（我只知道如何导入它们）

private void LoadImages() 
{ 
    for (int i = 0; i < trees.Length; i++) 
    { 
     string d = imagePath + trees[i].latinName + ".JPG"; 
     treesImage[i] = Image.FromFile(d); 
    } 
    //the image path is a constant 
    //trees[i].latinName is a string property 
    //treesImage is an array of Images created. 
    //so I'd like(preferably within my for loop to create the .bmp's and scale down 
    //using a const value such as const int width = 400, const int height = 300; 
    //and I'd lke to save the image to a different diretory than imagePath 
} 

如果有其他任何你想知道的后下方，我将修改的问题

Answer 1

试试这个：

int newWidth = 75; 
int newHeight = 50; 
for (int i = 0; i < trees.Length; i++) 
{ 
    string d = imagePath + trees[i].latinName + ".JPG"; 
    Image image = Image.FromFile(d); 

    //new image with size you need 
    Bitmap smallImage = new Bitmap(newWidth, newHeight); 
    Graphics g = Graphics.FromImage(smallImage); 

    //draw scaled old image to new with correct size 
    //g.drawImage(Image sourceImage, Rectangle destination, Rectangle source, GraphicsUnit gu) 
    g.DrawImage(image, new Rectangle(0, 0, smallImage.Width, smallImage.Height), new Rectangle(0, 0, image.Width, image.Height), GraphicsUnit.Pixel); 

    //format of new image is defined by it's name (.png/.jpg) 
    smallImage.Save(trees[i].latinName + "_new.png"); 
}