如何使用 C# Dot Net Core 压缩图像大小

Question

I am using .NET Core 2.2 In my code, I am using IFormFile to upload images. How can I compress the image size (to KB) just before it is uploaded to the server ? I search for solutions but those answers were related to Bitmap but since I am using IFormFile therefore I want solution related to it.

I will internally check the image size and if its size is upto 700KB, I don't want to compress. But if it is higher, then I want to compress and upload. Sample codes would be very useful

I tried to use Magick.NET package. But the problem is, how can I make IFormFile to MagickImage type ?

foreach(IFormFile photo in Images)  
{
  using (MagickImage mi = photo)  // Cannot implicitly convert type 
                                  //Microsoft.AspNetCore.Http.IFormFile to ImageMagick.MagickImage
   {
      mi.Format = Image.Jpeg;
      mi.Resize(40, 40);
      mi.Quality = 10;
      mi.Write(imageFile);
   }
}

Answer 1

I have used Magick.NET library which is available for both .NET and .NET Core to compress images. Refer to its documentation for more details.

In your case you either need to save the image temporarily somewhere and use the path (similar to my example), or convert it to an array of byte in memory and read that since it accept Byte[]

     using (MagickImage image = new MagickImage(@"YourImage.jpg"))
       {
           image.Format = image.Format; // Get or Set the format of the image.
           image.Resize(40, 40); // fit the image into the requested width and height. 
           image.Quality = 10; // This is the Compression level.
           image.Write("YourFinalImage.jpg");                 
        }