The purpose of this narrative is to describe the barest essential information for the general computer user to view, enter and edit the image identification information. That will, unfortunately, require some tedious background discussion and definition of technical terms and acronyms that will appear. This is a technical, complex and confusing subject, so distilling it to a brief introduction was a challenge. This narrative presumes basic knowledge of computer use and general terminology. This discussion will apply only to PC's. Sorry Mac.
The term "image" here refers to a photo file from a digital camera or on a computer being a "still" (i.e. non-moving) photo. It can also refer to the output of a scanner. There are many different types of images from a technical perspective, the most applicable types here being jpg and tiff which are the primary focus of this discussion. (Other formats frequently seen, but outside the scope of this discussion, are BMP, PNG and GIF.) "JPG" is the type of image produced by digital cameras and is most often used for those displayed on the internet. "TIFF" or "TIF" is typically used for higher-resolution images produced for professional/commercial applications or archival storage. "Image" will usually be used generically here, but application of differing programs to a specific type will vary by type; try to make clear.
The descriptive information contained within a digital image file is called "metadata" and that term is used frequently in the various discussions and documentation. "Metadata" has become an overused and confusing buzzword in cyberspace but in its most elementary definition is simply "data about data." Its more precise and correct meaning depends on the exact context of the discussion. In the context here of still images, it is simply the descriptive data about the image that is embedded within the computer file of that image. You will see the term metadata used constantly in the various other external discussions about images.
The embedded metadata in still image files is only visible or changeable by computer software programs specifically designed to access it. Further, the presence of this data does not affect and is ignored by software programs not designed to be aware of it. The embedded data in still image files falls into the following type/classifications/standards. These will be the acronyms/buzzwords that are used by the various programs and standards so that's why they are being presented. Unfortunately this is necessary since there is no consistent, authoritative simple descriptive terminology set for all this. The ones most common and important standards to know are: Exif, Comments, IPTC and XMP. It is also important to note that these standards are not mutually exclusive. Data from one or all of these standards can co-exist within a single image file.
Exif for "Exchangeable image file format" is a specification created by the Japan Electronic Industry Development Association (JEIDA) to describe information inserted into the photo files by digital cameras. It applies only to JPG and TIFF and specifically not to JPEG 2000, PNG or GIF. (Probably also not to BMP as well.) Although the specification is not currently maintained by any industry or standards organization, its use by camera manufacturers is nearly universal and, consequently, this information will usually be present. Also, Exif data is very often used in images created by scanners, though reportedly the standard makes NO provision for inserting scanner-specific information.
This data is mostly technical characteristics of the photo and camera, but includes useful information such as date, time, etc. Interestingly, if the camera is appropriately equipped, GPS data can also be recorded.
For more discussion, see: Wikipedia: Exif
"JPG Comment" or just "Comment" is a field for user entry of any text about the image. It appears to be part of Exif and appears to be the only field available through Exif for user-entered descriptive text. It is independent of any fields described in the following standards. It is displayed separately (sometimes not at all) by the software programs I tried and the information must be entered separately as those programs apparently do NOT keep it in synchronization with any other fields.
"IPTC" is the acronym for the standard developed by the "International Press Telecommunications Council." As its name implies, this is a consortium of major news agencies. The "ITPC" standard was developed to facilitate content description for exchange of news, including photos, among these organizations. Consequently, the data structures and names reflect newspaper terminology and processing objectives.
The IPTC-defined set of metadata attributes applied to image files is part of a broader standard from the early 1990's that is known as the IPTC Information Interchange Model (IIM). The imbedded IIM image information is sometimes called "IPTC headers."
This standard is important because 1) it is the most common standard accepted and 2) its set of data elements is comprehensive. IPTC will be the term and standard most frequently encountered when using the editing tools.
For more discussion, see:
Wikipedia: IPTC and
Wikipedia: IPTC Information Interchange Model (IIM)
XMP is the acronym for "Extensible Metadata Platform" that Wikipedia describes as: "a standard for processing and storing standardized and proprietary medatada, created by Adobe Systems Inc.." It appears that, given this lofty-sounding definition and subsequent discussion. that XMP has a much larger potential scope of application than IPTC, but XMP's practical use so far is described as PDF, photography and photo editing applications. Wikipedia further states: "XMP can be used in PDF and other graphics formats, such as JPEG, JPEG 2000, GIF, PNG, HTML, TIFF, Adobe Illustrator, PSD, PostScript, and Encapsulated PostScript." This is a significant extension over Exif.
The most common metadata tags recorded in XMP data are derived from still another project called the Dublin Core Metadata Initiative These include things like title, description, creator, etc. XMP, Exif and IPTC data can coexist within the same file and the editing software is responsible for maintaining consistency. That is why some software tools, etc. describe their applicability as "IPTC/XMP." Supposedly, XMP has largely superseded IIM's file structure but the IIM attributes are defined in the IPTC Core schema for XMP.
There are differences between IPTC and XMP in their descriptions of fields which will be confusing to new users. Examples are:
IPTC XMP ------ --- Caption = Description Byline = Author
For more discussion, see: Wikipedia: XMP - Extensible Metadata Platform This article also includes a listing of XMP software tools, some of which also are used for Exif and IPTC data.
Although standards exist for definition of the metadata, the products I tried display the data differently. They all differ in their description or identification of data fields, differ in menu structures and layouts and differ in placement of the same metadata elements among menus. That is, of course, confusing when comparing or switching between programs. It is important to ensure that important data be recorded in places where all subsequent users and their software can find it. A trial-and-error and testing approach may be necessary.
Also, be alert as to which of the following maintain only IPTC or both IPTC and XMP data. Some don't clearly say. It is also important that those that do support both are able to properly keep both sets in synchronization. Although XMP support has been slow to arrive, I think it may be the predominant standard in the future, so software that supports and reliably synchronizes with XMP should be preferred.
Natively, IrfanView can display Exif metadata.
Apparently, it only works with JPG files.
Image > Information
will bring up the "IrfanView - Image properties" menu. This panel displays the technical data about the image. At the bottom of the panel are two buttons additional to the "OK" to close. Click on the "Comment" button on the lower right to display (but not edit) any previously entered comments. On the lower left is a button "IPTC info." Under native IrfanView, clicking on this button results in an error message: 'Can't load PlugIn "IPTC.DLL"! / Please download PlugIns from IrfanView homepage!' "PlugIns" are additional software program modules that expand the capabilities of the host program. In this case, IrfanView requires plugins to access and update the Exif and IPTC metadata. There are apparently no plugins to create XMP data and I have not seen "XMP" mentioned in any IrfanView menus or documentation. Two separate plugins are shown:
One can now enter/edit Comments and IPTC data. Note that the IPTC data menu appears to precisely follow the IPTC definitions, teminology and data structure layout - so it sounds "newspaperish." Descriptive text is entered in the "Caption" field (Caption(tab)/Caption:(field) which corresponds, for example, to the General(tab)/Description:(field) in PixVue. This is independent of the "JPG Comments" field (JPG Comments(button)/Comment:(field)) and the content must be manually duplicated in each of those fields. (Copy and paste works well.) The apparent main photo title heading entry box is found in the following section: Origin (tab)/Object Name: (equivalent to "General (tab)/Title:" section in PixVue, for example). Also, when entering just the descriptive metadata, Irfanview does not modify the Windows file date as do some other programs, such as PixVue.
Download at: iTag
PixVue has a rather unusual mode of operation that is not obvious, is not effectively communicated and took me some aggravation to figure out. Initial installation of the program proceeds typically. However, from the Start > Programs > PixVue menu, only the "PixView Help" option is displayed which is the user help and documentation file (generally good). PixVue itself does not launch like a regular program. Instead, it is necessary to go into Windows Explorer, or a similar file listing routine, right click on the image file to bring up the file's selection menu and then select either "PixVue" to perform some typical photo image tasks or "Annotate" to use PixVue's software edit the photo's metadata. I initially found this method to be somewhat awkward (maybe I'll get used to it), but I really like the layout of the metadata editing panels and clear descriptions of the data fields. And it seems to work. Note that is does modify the original Windows file date, unlike IrfanView, for example, which does not. Offhand, I do not see a way to turn off the modification. So, I could also recommend this program for quick, basic editing of the photo's metadata.
Softsea - PixVue info.
and Softsea - PixVue download
The last version I have used is 7 which cannot display or edit the extended metadata. It can only display basic Exif information through: View > Photo Properties. Reportedly, later versions, possibly starting with 10, can display and edit the extended data.
See for more:
"Labelling Digital Photos" - Scroll to "Breezebrowser" section
"Google's Picasa (as of v.3) [Version 3, still as of January 2009] uses an older implementation of IPTC. To make Breezebrowser IPTC data show up in Picasa (Google uses the IPTC Description field for its Caption field) - go into "File > Preferences" and under the General tab select (add a checkmark) to "Also Store IPTC data in Legacy IPTC IIM format". That will make Breezebrowser's IPTC descrition [sic] field compatible with Picasa."
This procedure or technique may be possible with other software programs but I have not tested it.