Remove all metadata from common image formats?

Question

I'm writing a service for a project that's going to handle our image processing. One such process is supposed to strip all metadata from the byte[] provided and return the same image as a byte[].

The method I'm currently working on involves always converting the image to a Bitmap, then converting it back to the original format and returning the data from a MemoryStream.

I haven't been able to test it yet but something tells me I'm going to experience some quality loss.

How can I remove all metadata from any image with a common format?

(bmp, gif, png, jpg, icon, tiff)

Not sure how I can narrow that down any further. Would be nice if I got some feedback regarding the downvotes.

Answer 1

For the lossless formats (except JPEG), your idea of loading it as a bitmap and re-saving is fine. Not sure if .NET natively supports TIFFs (I doubt it does).

For JPEGs, as you suggested there may be quality loss if you're re-compressing the file after decompressing it. For that, you might try the ExifLibrary and see if that has anything. If not, there are command line tools (like ImageMagick) that can strip metadata. (If you use ImageMagick, you're all set, since it supports all of your required formats. The command you want is convert -strip.)

For TIFFs, .NET has built-in TiffBitmapDecoder and ...Encoder classes you might be able to use; see here.

In short, using an external tool like ImageMagick is definitely the easiest solution. If you can't use an external tool, you're almost certainly going to need to special-case the formats that .NET doesn't support natively (and the lossy JPEG).

EDIT: I just read that ImageMagick doesn't do lossless stripping with JPEGs, sorry. I guess using the library I linked above, or some other JPEG library, is the best I can think of.