Same Image, but different base64

Question

I used the following function to create a base64 encoded string of my Gravatar image (https://www.gravatar.com/avatar/cd5415f97afbe0177ba35ae31fbfd0db):

final BASE64Encoder encoder = new BASE64Encoder(); 

String encoded = encoder.encode(inputStreamToByteArray(is));
encoded = encoded.replaceAll("\r?\n", "");

return encoded;

I ran the method a couple of days ago and got the following base64 encoded string:

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

Just today I executed the method again, using the same image. But instead of retrieving the same encoded string, I received:

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

As you may notice, the first couple of characters are the same, but if you look at the end of the strings, you notice directly that they are completely different. Why is that? The image is still my Gravatar image (e.g., using http://codebeautify.org/base64-to-image-converter shows the same image for both strings).

Thanks for any hint, explanation! Is there anything wrong with my implementation? Is some of the implementation time or location dependent? How can I get the same base64 string for the same image?

PS: inputStreamToByteArray is implemented as follows:

public static byte[] inputStreamToByteArray(final InputStream is) {
    final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
    final byte[] data = new byte[16384];

    try {
        int nRead;
        while ((nRead = is.read(data, 0, data.length)) != -1) {
            buffer.write(data, 0, nRead);
        }
        buffer.flush();
    } catch (final IOException e) {
        return null;
    } finally {
        try {
            buffer.close();
        } catch (final IOException e) {
            // ignore
        }
    }

    return buffer.toByteArray();
}

Answer 1

Converting both images back to .jpg, and using http://regex.info/exif.cgi, the following header comments appear:

One:

CREATOR: gd-jpeg v1.0 (using IJG JPEG v80), quality = 90

Other:

CREATOR: gd-jpeg v1.0 (using IJG JPEG v62), quality = 90

(can't remember which order I converted the images in, but there is a version change either way)

As you can see, they have upgraded the JPEG compressor (or spec?) to a newer version, resulting in a different JPEG encoding, or at least difference in the comments.

So to answer your question, there does not seem to be an issue with your base64 converter, but just that the two images actually are different