JPEG 2000 support in C#.NET

Question

It seems that .NET can't open JP2 (Jpeg 2000) files using the GDI library. I've searched on google but can't find any libraries or example code to do this.

Anybody got any ideas? I don't really want to pay for a library to do it unless I have to..

Answer 1

Seems like we can do it using FreeImage (which is free)

FIBITMAP dib = FreeImage.LoadEx("test.jp2"); //save the image out to disk     FreeImage.Save(FREE_IMAGE_FORMAT.FIF_JPEG, dib, "test.jpg", FREE_IMAGE_SAVE_FLAGS.JPEG_QUALITYNORMAL); //or even turn it into a normal Bitmap for later use Bitmap bitmap = FreeImage.GetBitmap(dib); 

Answer 2

For anyone coming across this old post, the above code from Gordon works great, but as jixtra pointed out, you will indeed get an exception: System.DllNotFoundException: 'Unable to load DLL 'FreeImage': The specified module could not be found.' when installing via nuget. I was able to get it working in .net 4.6.1 by installing the FreeImage-dotnet-core nuget package and manually adding the FreeImage.dll to the bin folder. You can download the dll here: http://freeimage.sourceforge.net/download.html.

I needed a better quality image to use with tesseract so I made a few minor changes which made a huge difference to the quality of the new jpeg:

var jp2Format = FREE_IMAGE_FORMAT.FIF_JP2; var dib = FreeImage.LoadEx("test.jp2", ref jp2Format);  FreeImage.SetResolutionX(dib, 300); FreeImage.SetResolutionY(dib, 300); FreeImage.Save(FREE_IMAGE_FORMAT.FIF_JPEG, dib, "test.jpg", FREE_IMAGE_SAVE_FLAGS.JPEG_QUALITYSUPERB);