ImageMetadata - Revision history

Soliton: /* Image Metadata */

2026-02-18T12:36:36Z

‎Image Metadata

Doofus-01: /* Metadata and Image Editors */

2025-08-23T13:05:05Z

‎Metadata and Image Editors

Doofus-01: /* Authorship and Copyright */

2025-08-23T12:15:36Z

‎Authorship and Copyright

Elvish Hunter: /* Basic usage of exiftool */ Updated command for EXIF tags (without "EXIF:" it didn't work correctly for me on PNG files)

2025-07-23T14:23:47Z

‎Basic usage of exiftool: Updated command for EXIF tags (without "EXIF:" it didn't work correctly for me on PNG files)

Doofus-01: /* Examples */

2025-05-26T18:21:07Z

‎Examples

Doofus-01: /* Basic usage of exiftool */

2025-05-26T18:08:22Z

‎Basic usage of exiftool

Doofus-01: /* Authorship and Copyright */

2025-05-26T18:03:20Z

‎Authorship and Copyright

Doofus-01: corrections and examples

2025-03-23T12:16:47Z

corrections and examples

Doofus-01 at 03:09, 23 March 2025

2025-03-23T03:09:39Z

Doofus-01: some formatting

2025-03-23T03:07:13Z

some formatting

@@ Line 1: / Line 1: @@
 == Image Metadata ==
-Author and copyright data of Wesnoth images are contained in the image metadata.  For most of Wesnoth's project history, image authorship and copyrights were tracked in a separate text document.  Such a document can still be generated from the metadata, but is not currently (2025) part of the commit process.  There is no expectation that an artist correctly format the metadata, but the individual committing the image to the project files is expected to do so.
+Author and [[Wesnoth:Copyrights#The_Battle_for_Wesnoth_-_Visual_and_Audio_Contributions|copyright]] data of Wesnoth images are contained in the image metadata.  For most of Wesnoth's project history, image authorship and copyrights were tracked in a separate text document.  Such a document can still be generated from the metadata, but is not currently (2025) part of the commit process.  There is no expectation that an artist correctly format the metadata, but the individual committing the image to the project files is expected to do so.
 A lot of different programs can manipulate metadata, and they all seem to have different ways of doing it.

@@ Line 36: / Line 36: @@
 ===Metadata and Image Editors===
 ====GIMP (2.10)====
 ''Image->Metadata->Edit Metadata''
@@ Line 47: / Line 51: @@
 *WEBP - Does not seem to import anything, but can write XMP:Creator and XMP:Rights
 *JPEG - Can import EXIF:Artist and EXIF:Copyright, shown under "Dublin Core" as Creator & Rights, exported under IPTC:By-line and IPTC:Copyright Notice
 ===Examples===

@@ Line 25: / Line 25: @@
 ====Authorship and Copyright====
-To satisfy CI, image metadata is checked for a small set of entries.
+To satisfy github continuous integration (CI), image metadata is checked for a small set of entries.
 For PNG, JPEG, WEBP:
-* '''EXIF:Artist''' must exist.
+* '''EXIF:Artist''' must exist.  The format is "Real Name (screen/account name)" with each person separated by a semicolon (;) and either real name or screen name may be omitted.  More than one "artist" does not imply a collaboration, it may just mean there was a visible edit to the image.
-* '''EXIF:Copyright''' must contain "GNU GPL v2+", "CC BY-SA 4.0", or "CC0"
+* '''EXIF:Copyright''' must contain "GNU GPL v2+", "CC BY-SA 4.0", or "CC0".  The copyright cannot be changed arbitrarily.
 ====Optional tags reported in CI====

@@ Line 19: / Line 19: @@
 * EXIF - Used for WEBP, JPG and PNG, as Exif data seemed more visible in some file managers.  We could add both XMP and Exif to all images, but that would make the files larger.
-     exiftool -overwrite_original -all= -CreateDate="<Y:m:d H:M:S>" -Copyright="<copyright>" -Artist="<name (account name)>" -UserComment="<comment>" <target file>
+     exiftool -overwrite_original -all= -EXIF:CreateDate="<Y:m:d H:M:S>" -EXIF:Copyright="<copyright>" -EXIF:Artist="<name (account name)>" -EXIF:UserComment="<comment>" <target file>
 ===Metadata and CI===

@@ Line 50: / Line 50: @@
 ===Examples===
-A sprite (PNG) with the needed XMP tags is shown below.
+A sprite (PNG) with the needed EXIF tags is shown below.
-https://forums.wesnoth.org/download/file.php?id=99456&type=.png
+https://forums.wesnoth.org/download/file.php?id=99973&type=.png
 Examples of WebP showing the Alpha flag issue can be found at this forum post:

@@ Line 15: / Line 15: @@
 To write the needed metadata (Author and Copyright) but remove all the other info injected by image editors (most of which is useful in some context, just not this one), we use ''-all='' to clear the deck.  For small PNG files, thumbnail data can double the file size, and this matters because we have ''a lot'' of these little files.  We can also use ''-overwrite_original'' to prevent a backup file.  Different tag groups have different names for very similar fields, and they often don't match what you see in the image editor dialogs.
-* XMP (dc "Dublin Core") tags - Used for PNG because they are most likely to be edited with GIMP (see below).
+* XMP (dc "Dublin Core") tags - were briefly used for PNG because they are most likely to be edited with GIMP.  However, this fact was not worth the extra size and complication, so they are no longer used.  Please use the EXIF tags for PNG, just like JPG and WEBP.
      exiftool -overwrite_original -all= -Date="<Y:m:d H:M:S>" -Rights="<copyright>" -Creator="<name (account name)>" -Description="<comment>" <target file>
-* EXIF - Used for WEBP and JPG, as Exif data seemed more visible in some file managers.  We could add both XMP and Exif to all images, but that would make the files larger.
+* EXIF - Used for WEBP, JPG and PNG, as Exif data seemed more visible in some file managers.  We could add both XMP and Exif to all images, but that would make the files larger.
      exiftool -overwrite_original -all= -CreateDate="<Y:m:d H:M:S>" -Copyright="<copyright>" -Artist="<name (account name)>" -UserComment="<comment>" <target file>

@@ Line 12: / Line 12: @@
 To view metadata of an image <file> grouped by tag
      exiftool -g <file>
-'''Note:''' WEBP must contain "Alpha" in RIFF:WebP_Flags or else the transparent background will be lost when EXIF tags are added.  Exiftool can read but not write this flag (so ''-all='' argument won't clobber it).  GIMP will set this flag, but some optimizing scripts or programs can remove it.  Viewing the image metadata with the above command will allow you to check.
+'''Note:''' WEBP must contain "Alpha" in RIFF:WebP_Flags or else the transparent background will be lost when EXIF tags are added.  Exiftool is supposed to read but not write this flag (so ''-all='' argument shouldn't clobber it, but sometimes it does).  GIMP will set this flag, but it can get removed by further processing.  Viewing the image metadata with the above command will allow you to check.
 To write the needed metadata (Author and Copyright) but remove all the other info injected by image editors (most of which is useful in some context, just not this one), we use ''-all='' to clear the deck.  For small PNG files, thumbnail data can double the file size, and this matters because we have ''a lot'' of these little files.  We can also use ''-overwrite_original'' to prevent a backup file.  Different tag groups have different names for very similar fields, and they often don't match what you see in the image editor dialogs.
@@ Line 37: / Line 37: @@
 * '''EXIF:Copyright''' must contain "GNU GPL v2+", "CC BY-SA 4.0", or "CC0"
-(Examples would be nice, but uploads are not allowed.)
 ====Optional tags reported in CI====
 (This needs to be fixed, both here and CI.)
@@ Line 54: / Line 54: @@
 *JPEG - Can import EXIF:Artist and EXIF:Copyright, shown under "Dublin Core" as Creator & Rights, exported under IPTC:By-line and IPTC:Copyright Notice
 == See also ==

@@ Line 31: / Line 31: @@
 * '''XMP:Rights''' must contain "GNU GPL v2+", "CC BY-SA 4.0", or "CC0"
-−
 For JPEG, WEBP:
 * '''EXIF:Artist''' must exist.
@@ Line 37: / Line 37: @@
 * '''EXIF:Copyright''' must contain "GNU GPL v2+", "CC BY-SA 4.0", or "CC0"
 ====Optional tags reported in CI====
 (This needs to be fixed, both here and CI.)
@@ Line 42: / Line 43: @@
 ===Metadata and Image Editors===
 ====GIMP (2.10)====
-Image->Metadata->Edit Metadata
+''Image->Metadata->Edit Metadata''
 *PNG - Can read/write XMP:Creator, XMP:Rights, and XMP:Description under the "Description" tab
 *WEBP - Can read/write XMP:Creator, XMP:Rights, and XMP:Description under the "Description" tab
@@ Line 48: / Line 49: @@
 ====Krita (5.1)====
-Layer->Edit Metadata...
+''Layer->Edit Metadata...''
 *PNG - Does not always import XMP:Creator or XMP:Rights, but can write to them under "Dublin Core" tab, as well as XMP:Description
 *WEBP - Does not seem to import anything, but can write XMP:Creator and XMP:Rights