Commons:First steps/Quality and description

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First steps
First steps tour
Tips & tricks
Third parties
How to make perfect media uploads.

Images[edit]

A space probe image of Saturn's moon Titan uploaded in the highest available quality as well as the recommended image description (click image in order to see the image page)

Generally speaking, image quality and resolution should be as high as possible so images can be used in high-quality printouts, for example. MediaWiki, the server-side wiki software behind Wikimedia projects, can scale images in most formats on the fly as needed and storage space is not restricted, so concerns about download time and size should not keep you from uploading the highest resolution file available.

Size and scaling[edit]

As of May 1, 2013, the MediaWiki software can't handle GIF and TIFF images larger than exactly 50 megapixels — but otherwise images in such high resolutions are fine. For animated GIFs, you have to multiply the resolution with the frame count. PNGs are thumbnailed if they are smaller than approximately 2,500 megapixels (2,500,000,000 pixels) — 50,000×50,000 pixels square (1.00:1), 57,732×43,299 pixels in the 4:3 aspect ratio (1.33:1), 63,600×39,307 pixels in the golden ratio (1.62:1), or 66,656×37,494 pixels in the 16:9 ratio (1.78:1)

The upload size limit was increased to 100 MB at the end of 2008. With chunked uploading, e.g. available through Upload Wizard (a modern Browser is required), it is possible to upload files with a file size up to 500 MB.

Filetypes and naming[edit]

Only certain file types are allowed in Wikimedia Commons. If you try to upload a different file type, you'll receive an error message.

The destination filename you give will be the title of the image description page; you may want to follow naming conventions. If you modify an image of others, please upload it under a different filename and add links to and from the original.

Format guidance[edit]

Different formats should be used for different types of images. JPEG works well with images with lots of details like photographs. A diagram, however, suffers compression artifacts when saved as JPEG and, like GIF and PNG, cannot be scaled without loss of quality. SVG works well with charts, diagrams, and other images where there are few details. (However, if you can't get the diagram in vector form, PNG is still better than JPEG.) SVG can be edited easily and scaled with no loss of quality, but its use in photographs, for instance, is impractical. GIF is cumbersome for use with the server software and due to inherent restrictions in the format, use of GIF should be restricted to animated images only. For further information on image formats, format conversion, and other format recommendations, see Commons:Preparing images for upload.

  • Photographs: For photographs, use JPEG (file extension .jpg or .jpeg). While TIFF offers higher quality, these files tend to be rather large, especially when they are not compressed. PNG uses a lossless compression (that is: no information is removed) and is thus theoretically better for photographs, but it too produces excessively large file sizes for high-resolution photographs. PNG should be reserved for images that require high quality and/or that it can more easily compress, such as computer screenshots (or diagrams only available in raster form). Do not save JPEG images as "progressive".[1] Please optimize JPEG images (this reduces size at no cost to decoding).[clarification needed]
  • Animated images: For animated images, use GIF (file extension .gif).
  • Diagrams: For diagrams, charts, etc., SVG (Scalable Vector Graphics, file extension .svg) is the preferred type (or, if you can't get vectors, use PNG).

Audio and video[edit]

Supported sound types are MIDI (file extension: .mid) and Ogg Vorbis (.ogg) and for video files WebM (.webm) or Ogg Theora (also .ogg or .ogv). Other widely used sound file formats like MP3 or WMA and video formats like MPEG and WMV are not allowed at Wikimedia Commons due to patent issues. Like images, quality of sound and video files should not be too low. The upper limit for file sizes is 100 megabytes, so choose quality depending on the duration of your media file. For information on format conversion and encoding, see Commons:Software.

Good file descriptions[edit]

A good file description provides complete information about the file, including legally required information such as its copyright status and source, as well as descriptive information about what it shows and how it was made. Without this information making judgements about the provenance of an image is very difficult and its value is much reduced to editors and researchers.

The following is neither possible nor required if you use Upload Wizard for uploading, which is the default way for uploading at Commons now.

To assist you in creating such a description, there is a standardized template for images. Additionally, this template is rendered in a typographically sound way and provides Machine-readable data which in turn is used for creating information for reusers. It is therefore highly recommended to use the template (N.B. there are special templates for works of art {{Artwork}} and books {{Book}} that should be used in place of (or, in the case of some photographs, in addition to) the template {{Information}} shown hereafter, see the relevant template documentation pages for more information). Just copy the code below, paste it into the "Summary" field during upload and fill in the blanks:

{{Information
|Description=
|Source=
|Date=
|Author=
|Permission=
|Other_versions=
}}
Photo of the Orion Nebula with the recommended description describing how the image was made and a quoted grant from the copyright owner (click image in order to see the image page)
The fields are used the following way

If you can't fill in everything, leave them blank, as the template won't work as advertised otherwise (internationalization, categorization).

Description
Description of the content. What do you see, hear, or otherwise perceive? If it's an artwork, please provide brief historical background. In case of scientific data, a brief scientific abstract of the file. If you have detailed information about an image, for example the name of the species or the size of the object, please add it. Especially with mineral images, including the size is helpful. Stating where a photograph was taken never hurts and is often essential, as for almost any non-astronomical photograph taken outdoors, among others. Descriptions can be in any language, but it is always a good idea to include an English description as well. If you can write in more than one language, consider adding the description in all of them. See this note about creating wikilinks.

The following is neither possible nor required if you use Upload Wizard for uploading, which is the default way for uploading at Commons now.

You should use templates to declare language(s) of the description. It can look like:
{{Information
|Description=
{{cs|1=Nějaký český popisek.}}
{{en|1=Some description in English.}}
…
|Source=…
Source
Use the template {{own}}, if you created that file yourself. Otherwise please supply a
  • Link to a website, with a direct link to the page embedding the file and a direct link to the file
  • Catalog number
  • Name of institution
  • Book source
  • Etc.
See also Commons:Essential information#Source.
Date
Date of creation (or date of release), preferably in ISO 8601 format, such as 2006-01-15 for 15 January 2006.
Author
Author(s) of the file. If you don't know any individual, use the name of the institution(s) which released it. In case of self-made work, put your real name (or pseudonym), and link to your username such as "[[User:JQPublic|JQPublic]]", which will be rendered as "John Q. Public". Alternatively, link to your username in parentheses, such as "John Q. Public ([[User:JQPublic|JQPublic]])", which will be rendered as "John Q. Public (JQPublic)".

The following is neither possible nor required if you use Upload Wizard for uploading, which is the default way for uploading at Commons now.

Permission
Note: You still need to tag the image in any case with the appropriate license template (aka Copyright tag)!
Supply a short quote of the permission the copyright owner of the file gave you. In case of a general permission (e. g. US Public Domain or free content licenses) supply a short link to that legal disclaimer or an according hint. If you are the copyright owner, but not the author, please indicate this here; if you are the author and copyright-holder, leave it blank and use {{own}} as the source and make sure, you wrap your Copyright tag in {{self}} (e.g. {{self|Cc-by-sa-3.0}}).
Other versions of this file
If there are other version of this file within Wikimedia Commons (for example a black and white version of a color image, or a cropped or uncropped version) use this field to link to these versions with a wikilink.

Note: For many media it is desirable to use a geocoding template in addition to the Information template. Please also read First steps/Sorting.

Upload summary[edit]

When you are uploading a file, the upload form gives you a place for a summary. The first 255 characters of your summary will appear permanently on the image description page, in the "File history" section.

If you are uploading the first version of a file (there is not already a file with the title you selected), then your upload summary will also be copied to the image description page. It is common in this case to provide complete information in the summary, as detailed under Good file descriptions hereinbefore.

If you are uploading a new version of a file, it is important to specify in as much detail as possible how you changed the file. This information is important because it can be difficult for others to tell the difference between two files. For example, for an image, you could say:

Cropped 25 pixels off the top, brightened with Photoshop, saved at 95% quality

Ideally, one will provide a command line or exact list of commands that reproduces the changes, though this is by no means necessary, and often not possible.

Notes[edit]

  1. Progressive images break the thumbnailer, because the whole image must be rendered, thus exhausting memory. See archived discussion and example.

Further reading[edit]

Wikimedia Commons pages:

Wikipedia page:

MediaWiki handbook: