CODEWITHSUNDEEP
c#jpegmemorystream
pavlindrom
pavlindrom

Reputation: 393

Find the image type from a memory stream

I am writing some code to convert some images stored in a database to JPEG. I need to check if the image isn't JPEG, and all I have is a byte[] that I am putting into a MemoryStream. The current code then plugs that into a Bitmap, which doesn't tell me anything about the image.

Upvotes: 1

Views: 1265

Answers (2)

David Crowell
David Crowell

Reputation: 3813

You could check the first few bytes. Most, but not all, JPEG files start with the byte sequence FF D8 FF. If you need to be sure, you'll need to do a bit more.

I wrote a VB class fifteen years ago to do this. I still find copies of it floating around the web: https://code.google.com/p/vbgore/source/browse/trunk/Code/GrhDatMaker/CImageInfo.cls?spec=svn45&r=45

It's easy enough to read. This should be faster than loading into an Image class.

Upvotes: 0

Yuval Itzchakov
Yuval Itzchakov

Reputation: 149618

Checkout the Image.RawFormat property. Once you load the image from the stream you could do:

if (ImageFormat.Jpeg.Equals(image.RawFormat))
{
    // Image is JPEG
}

Upvotes: 2

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