在 C# 中将文件转换为位图

Question

I write this code to read files from folder in directory(@"D:\\\\test\\\\ISIC_2020_Training_JPEG") , then convert each file to bitmap in c#

foreach (string img in Directory.EnumerateFiles(@"D:\\test\\ISIC_2020_Training_JPEG"))
    Bitmap  bmp = new Bitmap(img);

But there is an error that appears in the last line, which is:

Out of memory Exception

what is the problem in this code?

Answer 1

I suppose that you have all jpeg files on provided directory, you could load image file in memory stream and check if everything okay when you load image in memory stream.

foreach (string imgPath in Directory.GetFiles(@"D:\test\ISIC_2020_Training_JPEG"))
{
    Bitmap  bmp;
    byte[] buff = System.IO.File.ReadAllBytes(imgPath);
    using(System.IO.MemoryStream ms = new System.IO.MemoryStream(buff))
    {
        bmp = new Bitmap(ms);
    }
}
    

Answer 2

Probably the best approach would be to stream the image files so if there's a large file it won't hog up too much memory. Then check if the file is in the correct format before trying to convert to a Bitmap , hopefully this helps:

Bitmap bitmap;
Image image;
foreach (string imgFile in Directory.EnumerateFiles(@"D:\test\ISIC_2020_Training_JPEG"))
{
    using (Stream bmpStream = File.Open(imgFile, FileMode.Open))
    {
        image = Image.FromStream(bmpStream);
        if (ImageFormat.Jpeg.Equals(image.RawFormat)) // Check it's the correct format
        {
            bitmap = new Bitmap(image);
        }
    }
}