Reading base jpg and png tags

[perdrix52]

exiftool can read the base level png and jpg tags that are not EXIF. For example:

C:\Users\amonra\Downloads\ExifTool>exiftool "C:\Users\amonra\Pictures\_MG_1306.png"
ExifTool Version Number         : 12.55
File Name                       : _MG_1306.png
Directory                       : C:/Users/amonra/Pictures
File Size                       : 118 kB
File Modification Date/Time     : 2015:12:18 16:24:48+00:00
File Access Date/Time           : 2023:04:21 17:32:43+01:00
File Creation Date/Time         : 2022:11:16 15:26:34+00:00
File Permissions                : -rw-rw-rw-
File Type                       : PNG
File Type Extension             : png
MIME Type                       : image/png
Image Width                     : 276
Image Height                    : 182
Bit Depth                       : 8
Color Type                      : RGB with Alpha
Compression                     : Deflate/Inflate
Filter                          : Adaptive
Interlace                       : Noninterlaced
SRGB Rendering                  : Perceptual
Gamma                           : 2.2
Pixels Per Unit X               : 3779
Pixels Per Unit Y               : 3779
Pixel Units                     : meters
Image Size                      : 276x182
Megapixels                      : 0.050


C:\Users\amonra\Downloads\ExifTool>exiftool "C:\Users\amonra\Pictures\Firewall.jpg
ExifTool Version Number         : 12.55
File Name                       : Firewall.jpg
Directory                       : C:/Users/amonra/Pictures
File Size                       : 109 kB
File Modification Date/Time     : 2022:12:15 15:44:24+00:00
File Access Date/Time           : 2023:04:21 17:39:55+01:00
File Creation Date/Time         : 2022:12:15 15:44:21+00:00
File Permissions                : -rw-rw-rw-
File Type                       : JPEG
File Type Extension             : jpg
MIME Type                       : image/jpeg
Exif Byte Order                 : Big-endian (Motorola, MM)
    :
    :
Image Width                     : 1020
Image Height                    : 291
Encoding Process                : Baseline DCT, Huffman coding
Bits Per Sample                 : 8
Color Components                : 3
Y Cb Cr Sub Sampling            : YCbCr4:4:4 (1 1)
   :
   :

C:\Users\amonra\Downloads\ExifTool>

Can Exiv2 be used to read these?

Thank you

[clanmills]

I'm not sure that I have understood your question. Exiv2 reads Exif, XMP, IPTC and ICC metadata. If you're asking about the FileSystem data such as Directory, the sample application exiv2json can do that.

535 rmills@rmillsm1:~ $ exiv2json f ~/Stonehenge.jpg  
{
	"FS": {
		"path": "\/Users\/rmills\/Stonehenge.jpg",
		"realpath": "\/Users\/rmills\/Stonehenge.jpg",
		"st_dev": 16777231,
		"st_ino": 109961837,
		"st_mode": 33188,
		"st_nlink": 1,
		"st_uid": 501,
		"st_gid": 20,
		"st_rdev": 0,
		"st_size": 6757987,
		"st_atime": 1686936463,
		"st_mtime": 1686936461,
		"st_ctime": 1686936461,
		"st_blksize": 4096,
		"st_blocks": 13312
	}
}
536 rmills@rmillsm1:~ $ 

Data about the File System is not part of the four supported standards and, therefore not reported.

[perdrix52]

I wasn't asking about the filesystem stuff - rather I was asking about the other tags in the file

[clanmills]

Which tags are missing? Exiftool and Exiv2 use different tag names, however, both tools report the same tags (Exif 2.32 spec).

[clanmills]

@perdrix52 David: There is format specific metadata which exiv2 does not report. For example, PNG files can store "Textual Information" and this is discussed in my book under "11.3.4 Textual information" https://exiv2.org/book/index.html#PNG

Exiv2 provides support for the Exif/XMP/IPTC/ICC standards and doesn't report format specific metadata.

[perdrix52]

OK - thanks

[clanmills]

@perdrix52 David: Thanks for closing this. Please re-open this issue if you believe it merits more discussion.