IPTC: Envelope values "Character set" and "ModelVersion" result in broken Codepage

Run this snippet with Magick.NET 7.22.3.0:

var raw = new byte[]
{
    // A naked 10x10 pixel jpg.
    0xFF, 0xD8, 0xFF, 0xE0, 0x00, 0x10, 0x4A, 0x46, 0x49, 0x46, 0x00, 0x01, 0x01, 0x01, 0x00, 0x48, 0x00,
    0x48, 0x00, 0x00, 0xFF, 0xDB, 0x00, 0x43, 0x00, 0x02, 0x01, 0x01, 0x01, 0x01, 0x01, 0x02, 0x01, 0x01,
    0x01, 0x02, 0x02, 0x02, 0x02, 0x02, 0x04, 0x03, 0x02, 0x02, 0x02, 0x02, 0x05, 0x04, 0x04, 0x03, 0x04,
    0x06, 0x05, 0x06, 0x06, 0x06, 0x05, 0x06, 0x06, 0x06, 0x07, 0x09, 0x08, 0x06, 0x07, 0x09, 0x07, 0x06,
    0x06, 0x08, 0x0B, 0x08, 0x09, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x06, 0x08, 0x0B, 0x0C, 0x0B, 0x0A, 0x0C,
    0x09, 0x0A, 0x0A, 0x0A, 0xFF, 0xDB, 0x00, 0x43, 0x01, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x05, 0x03,
    0x03, 0x05, 0x0A, 0x07, 0x06, 0x07, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A,
    0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A,
    0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A,
    0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0xFF, 0xC0, 0x00, 0x11, 0x08, 0x00, 0x0A, 0x00, 0x0A, 0x03, 0x01, 0x22,
    0x00, 0x02, 0x11, 0x01, 0x03, 0x11, 0x01, 0xFF, 0xC4, 0x00, 0x15, 0x00, 0x01, 0x01, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x09, 0xFF, 0xC4, 0x00, 0x14,
    0x10, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0xFF, 0xC4, 0x00, 0x14, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xC4, 0x00, 0x14, 0x11, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xDA, 0x00, 0x0C, 0x03, 0x01,
    0x00, 0x02, 0x11, 0x03, 0x11, 0x00, 0x3F, 0x00, 0xBF, 0x80, 0x03, 0xFF, 0xD9
};

using (var stream = new MemoryStream())
{
    using (var image = new MagickImage(raw))
    {
        var iptcProfile = new IptcProfile();
        iptcProfile.SetValue(IptcTag.Byline, "Vašek");
        image.SetProfile(iptcProfile);

        image.Write(stream);
    }

    //Debug.WriteLine(string.Join(" ", stream.ToArray().Select(@byte => $"{@byte:X2}")));
    File.WriteAllBytes("test.jpg", stream.ToArray());
}

results in broken metadata (e.g. on left IrvanView doesn’t recognize UTF-8 / on the right IrvanView saves the IPTC with Character set and ModelVersion):

I drilled down the issue to the IPTC profile:

wrong (Magick.NET):
FF ED  00 28  50 68 6F 74 6F 73 68 6F 70 20 33 2E 30 00 38 42 49 4D 04 04 00 00 00 00  00 0B                                                 1C 02 50 00 06  56 61 C5 A1 65 6B           00
correct:
FF ED  00 36  50 68 6F 74 6F 73 68 6F 70 20 33 2E 30 00 38 42 49 4D 04 04 00 00 00 00  00 1A  1C 01 5A 00 03 1B 25 47  1C 01 00 00 02 00 04  1C 02 50 00 06  56 61 C5 A1 65 6B
Marker Length P  h  o  t  o  s  h  o  p     3  .  0     8  B  I  M                     Length       Character set            ModelVersion          Byline     V  a     š  e  k  EvenPadding

Is it possible to add this IPTC Envelope data? Maybe “Character set” is sufficient but I didn’t find any specification.

[dlemstra]

The new release has been published. Can you give it a try with that release?

[dlemstra]

Thanks for reporting this. I could add the IPTC Envelope.

I did find this about the character set (https://www.iptc.org/std/IIM/4.1/specification/IIMV4.1.pdf):

Optional, not repeatable, up to 32 octets, consisting of one or more control functions used for the announcement, invocation or designation of coded character sets. The control functions follow the ISO 2022 standard and may consist of the escape control character and one or more graphic characters. For more details see Appendix C, the IPTC-NAA Code Library. The control functions apply to character oriented DataSets in records 2-6. They also apply to record 8, unless the objectdata explicitly, or the File Format implicitly, defines character sets otherwise. If this DataSet contains the designation function for Unicode in UTF-8 then no other announcement, designation or invocation functions are permitted in this DataSet or in records 2-6. For all other character sets, one or more escape sequences are used: • for the announcement of the code extension facilities used in the data which follows, • for the initial designation of the G0, G1, G2 and G3 graphic character sets and • for the initial invocation of the graphic set (7 bits) or the lefth and and the right-hand graphic set (8 bits) and for the initial invocation of the C0 (7 bits) or of the C0 and the C1 control character sets (8 bits). The announcement of the code extension facilities, if transmitted, must appear in this data set. Designation and invocation of graphic and control function sets (shifting) may be transmitted anywhere where the escape and the other necessary control characters are permitted. However, it is recommended to transmit in this DataSet an initial designation and invocation, i.e. to define all designations and the shift status currently in use by transmitting the appropriate escape sequences and locking-shift functions. If 1:90 is omitted, the default for records 2-6 and 8 is ISO 646 IRV (7 bits) or ISO 4873 DV (8 bits). Record 1 shall always use ISO 646 IRV or ISO 4873 DV respectively.

Your bytes contain this:

1C #
01 #
5A # 90 (Coded Character Set)
00 # 
03 # size
1B # escape
25 # %
47 # G

The APPENDIX C is also in the document but I don’t understand what is written there. I could probably add what is written by IrvanView for now.

This also means I made a design mistake when creating IIptcProfile and IIptcValue. The encoding should be moved from the value to the profile. For now I can probably only support UTF8 and allow setting it at a later moment when I figure out how to write other encodings.