Bug: UserComment displays as hex/binary instead of decoded text

[rpuneet]

Problem

The UserComment EXIF tag contains an 8-byte character code prefix followed by text, but imx displays it as hex or "binary data" instead of decoding the text.

Examples

JPEG file:

imx:  "UserComment": "415343494900000053686f7420647572696e6720676f6c64656e20686f7572..."
exiftool: "UserComment": "Shot during golden hour, 3-stop graduated ND filter used"

CR2 file:

imx: "UserComment": {"size": 264, "type": "binary"}
exiftool: (decodes the text content)

Root Cause

UserComment format: 8-byte charset ID + variable-length text

• ASCII\0\0\0 (41534349490000) = ASCII encoding
• UNICODE\0 = UTF-16 encoding
• JIS\0\0\0\0\0 = JIS encoding

Acceptance Criteria

• Detect charset prefix (ASCII, UNICODE, JIS, or undefined)
• Decode text portion appropriately
• Handle edge cases (empty, malformed)
• Unit tests for each encoding type

Priority

Medium - Affects usability for photographers who add comments