# PHYSICSWIKI:Manual of Style/Images

PhysicsWiki contains millions of illustrative images and other electronic media. This page gives a very brief overview of how images are used in PhysicsWiki; for more information, see Image use policy, and see Help:Files on how to upload and include an image.

## Making images available

Images uploaded to PhysicsWiki are automatically placed into the file namespace, formerly known as the image namespace. This means that names of image pages start with the prefix "File:".

Inline linking of images on external sites for display on PhysicsWiki is disabled for several reasons:

1. inline linking to images on other sites is often considered "leeching"; content sites where the image is stored and from which it is retrieved may not like the new placement
2. allowing inline image linking makes it easier for vandals to post images from shock sites
3. allowing inline image linking makes it easier to introduce copyrighted images without obtaining an acceptable free license
4. inline linking to an image stored on another site increases the bandwidth use of that site, even though the site is not being viewed as intended

Instead, to place an image on PhysicsWiki, you will need to upload it.

### Obtaining images

All images on PhysicsWiki must comply with the image use policy. This means that they must be free for commercial use and alteration. However, some fair use of non-free content is allowed in limited circumstances.

Search for existing files through:

#### Making images yourself

You may take a photograph with your digital camera, scanner, or integrated mobile phone, draw an image or graph digitally, perhaps with a graphics tablet, or scan drawings and photos taken with a camera and then upload the image.

Try to avoid including text in images or diagrams; you can use Template:Annotated image to add text (and links) that users can interact with.

#### Finding images on the Internet

An extensive list of free image resources by topic can be found at: Public domain image resources. In addition to PhysicsWiki Commons, the Wikimedia Toolserver has a Free Image Search Tool (FIST), which automatically culls free images from the Wikimedia sister projects, Flickr and a few other sites. Several other useful, general purpose image search engines include: Google Image Search, Picsearch and Pixsta. Creative Commons licensed images with Attribution and Attribution-ShareAlike as their license may be used on PhysicsWiki. Images with any license restricting commercial use or the creation of derivative works may not be used on PhysicsWiki.

The Creative Commons site has a search page that can be used as a starting point to find suitably licensed images; make sure you check both the checkboxes "use for commercial purposes" and "modify, adapt, or build upon".

If you find an image on the Internet that is not available freely, you can email the copyright owner and ask for their permission to release it under a suitable license, adapting the boilerplate request for permission. If you cannot find a suitable image, you may also list your request at PhysicsWiki:Requested pictures, so that another contributor may find or create a suitable image.

See

### Editing images

The goal of editing an image is to improve its utility or quality. This may be done through cropping the image to focus on the relevant information, cleaning up artifacts from scanning printed images, correcting the color balance, removing the red-eye effect, or making other adjustments.

Readers won't understand this image if you don't tell them that you've zoomed in and cropped the image to show the details.

Some types of edits should be described in the image's caption. Generally, these are changes that the readers need to be informed of to understand what they are looking at. For example, if you crop an image to show an enlarged view of a small area, then you should explain that edit in the image's caption.

Other types of edits should not be described. Generally, these are changes that improve the presentation without materially altering the content. For example, if you slightly rotate a snapshot because the photographer held the camera at a crooked angle, or if you correct the contrast in a poor-quality scan, or if you blur the background to make the subject more prominent, then your changes should not be described in the PhysicsWiki article's caption. (It is still appropriate to identify your changes in the image's own description page.)

Some types of edits should not be made. Generally, these are changes that materially mislead the viewer about the subject of the image. For example, photographs of artwork and images containing text should not be reversed, even though it is normally acceptable to reverse or rotate an image of objects whose orientation is unimportant or arbitrary, like soap bubbles or bacteria. If the colors are integral to the image, such as in images of many traffic signs and animals, then you should not change the colors. It is usually appropriate to de-speckle or remove scratches from images, but such an action might be inappropriate for certain historical photographs. Editors must use their best judgment to determine when their changes improve the utility or quality of the image, and when their changes deceive the readers about significant facts.

For assistance in editing or improving images on PhysicsWiki, you may find the Graphics Lab a useful resource.

Logged in users with autoconfirmed accounts (meaning at least four days old and at least ten edits) can upload media to PhysicsWiki. It is recommended that only free licensed media, not fair use media, be uploaded to PhysicsWiki Commons. Media on PhysicsWiki Commons can be linked to in the same way as media of the same name on PhysicsWiki. To upload media to PhysicsWiki, go to special:upload and for PhysicsWiki Commons, go to commons:special:upload. For preferred file formats, see: Preparing images for upload.

#### Image description pages

Each image has a corresponding description page. On that page, one should document the source, author and copyright status of the image, using one of the pre-defined file copyright tags. It is important to add both descriptive (who, what, when, where, why) and technical (equipment, software, etc.) information at the time of creating the page, which will be useful and highly informative to later editors and readers.

To maximize the utility and educational value of an image, please describe its contents as fully as possible on the image's description page. For example, photographs of artwork benefit from documentation of the artist, title, location, dates, museum identification numbers, and so on. Images that are described only in vague terms (for example, "a cuneiform tablet" or "a medieval manuscript") are often less useful for PhysicsWiki and less informative to our readers.

Reliable sources, if any, may be listed on the image's description page. Generally, PhysicsWiki assumes in good faith that image creators are correctly identifying the contents of photographs they have taken. If such sources are available, it is helpful to provide them. This is particularly important for technical drawings, as someone may want to verify that the image is accurate.

To help editors find images, please remember to add categories to the image description page. Well-categorized and well-described images are more likely to be used.

In terms of physical memory on a computer, typical images on PhysicsWiki can range in size from a few kilobytes to several megabytes. Thus, images can easily form the primary bandwidth component of an article download. This can be a problem for readers on a low bandwidth connection. Slow downloads can lead to user frustration, so the article's memory footprint should be minimised.

PhysicsWiki aids the download performance by converting full images into thumbnails before they are transmitted. However, not all image formats provide a significant size reduction through this technique. In most browsers you can review the memory footprint of downloaded images by moving the cursor over the image, right-clicking, then selecting Properties. The resulting window will show the resulting file size in Kb or Mb. For best results, you may want to focus on reducing the size of the largest image files on a page, particularly when they are disproportionately large compared to other images.

There are several image file formats available, each with their own benefits and drawbacks. One method of reducing the image downloaded time is to change the chosen format.

• GIF images with a frame size larger than 12.5 million pixels (measured as pixel height × pixel width × number of frames in the animation) cannot currently be displayed in thumbnail form in PhysicsWiki articles. A thumbnail of a GIF image can be considerably larger in filesize than the original image. For the best results, try to upload GIF images in the framesize that you intend to use in the article.
• Animated GIF images have a few additional restrictions. Images larger than 12.5 million pixels (measured as pixel height × pixel width × number of frames in the animation) currently will only show the first frame of the animation in a thumbnail. When not using a GIF animation at its original frame size, consider creating an Ogg Theora movie of the animation.
• The PNG format is useful for storing graphics that contain text, line art, or other images with sharp transitions. It can achieve the same graphical results as a GIF file, and in many cases do so with a higher rate of file compression. For this reason, PNG format files are usually preferred to the GIF format. (However, for certain types of images, PNG thumbnailing is not as efficient as GIF thumbnailing, when Wikimedia GIF thumbnailing is enabled.)
• A JPEG or other compressed image format can be much smaller than a comparable GIF or PNG format file. When there is no apparent difference in quality, such as with a photograph that has no sharp graphical transitions, a compressed image format such as JPEG may be preferable for reasons of download performance. PhysicsWiki is often able to achieve much better compression of JPEG photograph thumbnails than comparable PNG images, and with little perceptible loss of quality.
• Where an image consists solely of line art, charts text and simple graphics, an SVG file can be significantly smaller than other graphics formats. This is because the data is encoded as a series of drawing commands, rather than as raster graphics. There are open source applications available for rendering graphics in SVG format. However, SVG thumbnails are rendered as PNGs.
• Rather than including an image gallery on an article, which could add significantly to the download size, consider creating a gallery/category on the PhysicsWiki Commons instead.

## How to place an image

### Image syntax

Example caption

To produce this box, use:
[[File:Example.png|thumb |alt=Example alt text |Example caption]]

To incorporate an image into an article (either a local image or any image that is at the PhysicsWiki Commons), you will need to use image syntax. Note that if an identically named file exists on PhysicsWiki and on Commons, it's not possible to link to the file on Commons as the syntax is same and the local file has higher priority. As an example in a simple form, in order to reproduce the image at the top of this page, insert the following text into an article:

[[File:Example.png|thumb|alt=Example alt text|Example caption]]
• The first parameter is the page name of the file page (e.g. File:Example.png). You must reproduce the exact name of the image file including its capitalization, spacing and not omit its file extension such as .jpg.
• The second "thumb" parameter forces the creation of a thumbnail, and must be in lower case.
• The third parameter, "alt=Example alt text", can be modified to specify suitable alt text. Alt text is meant for readers who cannot see the image. It summarizes the image's appearance, not its meaning, and is therefore unlike the caption. Alt text also helps search engines find PhysicsWiki articles.
• The last parameter, "Example caption", can be replaced with any suitable caption.

• The full set of options is more complex; however, the vast majority of images should be able to be displayed by using the above format.
• If the image does not show up and you are sure the syntax is correct, it may have been blacklisted. See MediaWiki:Bad image list for a list of such images.
• The "File:" prefix may be used interchangeably with "Image:":
[[Image:Example.png|thumb|alt=Example alt text|Example caption]]

#### Forced image size

As a general rule, images should not be set to a larger fixed size than the 220px default (users can adjust this in their preferences). If an exception to the general rule is warranted, forcing an image size to be either larger or smaller than the 220px default is done by placing a parameter in the image coding.

• "upright=1.2" (or "|frameless|upright=1.2" for plain pictures) resizes an image to approximately the given multiple of a user's preferred width. An image should generally be no more than "upright=1.8" (defaults to 400 pixels) wide; an image can be wider if it uses the "center" or "none" options to stand alone. e.g.
[[File:Example.png|thumb|upright=1.2|alt=Example alt text|Example caption]]
• Alternatively, a fixed size can be specified in the form |XXXpx, where XXX is replaced by a number of pixels, although this should be avoided where possible, since it overrides the user's default. For example:
[[File:Example.png|thumb|120px|alt=Example alt text|Example caption]]
• Lead images should usually be no wider than "upright=1.35" (defaults to "300px").
• In addition to the width restrictions, with the default value, larger images should generally be a maximum of 500 pixels tall, so that they can comfortably be displayed on the smallest displays in common use. This can be done by proportionately reducing the width.
• Images in which detail is relatively unimportant (for example, a national flag) can be smaller than usual.
• Images containing important detail (for example, a map, diagram, or chart) may need larger sizes than usual to make them readable.
• Images in which a small region is relevant, but cropping to that region would reduce the coherence of the image, may need to be larger than normal.
• Large, panoramic images, which may require larger sizes to make them viewable or readable.
• Images should be large enough to reveal relevant details without overwhelming the surrounding article text.
• The {{wide image}} and {{tall image}} templates display images that would otherwise be unreasonably wide or tall in a scrollable box.
• Similar types of images within an article often look appealing if they appear at the same pixel size.

#### Forced left justification

In most cases, images should be right justified on pages, which is the default placement. If an exception to the general rule is warranted, forcing an image to justify on the left side of a page is done by placing a parameter in the image coding in the form |left, for example:

[[File:Example.png|thumb|left|alt=Example alt text|Example caption]]

### Location

Multiple images in the same article can be staggered right-and-left. However, avoid sandwiching text between two images that face each other, and between an image and an infobox or similar. If multiple related images are being placed on the right, then the {{multiple image}} template may be useful.

Avoid placing images on the left at the start of any section or subsection, because it makes it harder for readers to find the beginning of the text. Images on the left are best placed somewhere after the first paragraph.

It is often preferable to place images of faces so that the face or eyes look toward the text. However, images of people need not be reversed simply to make the person's face point towards the text, and this should not be done if the reversal would materially mislead the viewer (e.g., by making the subject of the article or section appear to have a birthmark on the left side of his face, when the birthmark is actually on the right side).

An image should generally be placed in the section of the article that is most relevant to the image. Avoid referring to images as being on the left or right. Image placement is different for viewers of the mobile version of PhysicsWiki, and is meaningless to people having pages read to them by assistive software. Instead, use captions to identify images.

#### Avoid entering textual information as images

Do not use images to express textual information in place of real text. See Avoid entering textual information as images for more.

## Choosing images

### Pertinence and encyclopedic nature

Error creating thumbnail: File missing
This is not the best photograph to show what a helicopter is nor what the Sydney Opera House looks like.

Images must be relevant to the article that they appear in and be significantly and directly related to the article's topic. Because the PhysicsWiki project is in a position to offer multimedia learning to its audience, images are an important part of any article's presentation. Effort should therefore be made to improve quality and choice of images or captions in articles rather than favoring their removal, especially on pages which have few visuals.

Images are primarily meant to inform readers by providing visual information. Consequently, images should look like what they are meant to illustrate, even if they are not provably authentic images. For example, a photograph of a trompe-l'œil painting of a cupcake may be an acceptable image for Cupcake, but a real cupcake that has been decorated to look like something else entirely is less appropriate. Similarly, an image of an unidentified cell under a light microscope might be useful on multiple articles, so long as there are no visible differences between the cell in the image and the typical appearance of the cell being illustrated.

Articles that use more than one image should present a variety of material near relevant text. If the article is about a general subject for which a large number of good quality images are available, (e.g., Running), editors are encouraged to seek a reasonable level of variety in the age, gender, and race of any people depicted. Adding multiple images with very similar content is less useful. For example, three formal portraits of a general wearing his military uniform may be excessive; substituting two of the portraits with a map of a battle and a picture of its aftermath may provide more information to readers. You should always be watchful not to overwhelm an article with images by adding more just because you can.

Poor quality images (too dark, blurry, etc.) or where the subject in the image is too small, hidden in clutter, ambiguous or otherwise not obvious, should not be used. Contributors should be judicious in deciding which images are the most suitable for the subject matter in an article. For example:

• An image of a White-tailed Eagle is useless if the bird appears as a speck in the sky.
• Gloria Steinem looks best as a portrait photograph of herself alone, not with other individuals.
• A suitable picture of a hammerhead shark would show its distinctive hammer-like head, to distinguish it from other species of shark.
• A map of Moldova should show its frontiers with Romania and Ukraine, so people may know where the country is located in relation to its neighbors.
• Rice is best represented with an image of plain rice, not fried rice.
• Intangible concepts can be illustrated; for example, a cat with its claws out portrays aggression.

### Offensive images

Including information about offensive material is part of PhysicsWiki's encyclopedic mission. PhysicsWiki is not censored. However, images that can be considered offensive should not be included unless they are treated in an encyclopedic manner. Material that would be considered vulgar or obscene by typical PhysicsWiki readers should be used if and only if its omission would cause the article to be less informative, relevant, or accurate, and no equally suitable alternative is available. Per the Foundation, controversial images should follow the principle of 'least astonishment': we should choose images that respect the conventional expectations of readers for a given topic as much as is possible without sacrificing the quality of the article. Images that contain irrelevant or extraneous elements that might seem offensive or harassing to readers. For example, photographs taken in a pornography context would normally be inappropriate for articles about human anatomy.

It is very common to use an appropriate representative image for the lead of an article, often as part of an infobox. The image helps to provide a visual association for the topic, and allows readers to quickly assess if they have arrived at the right page. For most topics, the selection of a lead image is plainly obvious: a photograph or artistic work of a person, photographs of a city, or a cover of a book or album, to name a few.

Image selection for other topics may be more difficult and several possible choices could be made. While PhysicsWiki is not censored, as outlined in the above section on offensive images, the selection of the lead image should be made with some care with respect to this advice. Lead images are loaded and shown upon navigating to the page, and are one of the first things that readers will see. Editors should avoid using images that readers would not have expected to see when navigating to the page. Unlike other content on a page that falls below the lead, the lead image should be chosen with these considerations in mind.

1. Lead images should be images that are natural and appropriate visual representations of the topic; they not only should be illustrating the topic specifically, but should also be the type of image that is used for similar purposes in high-quality reference works, and therefore what our readers will expect to see. Lead images are not required, and not having a lead image may be the best solution if there is no easy representation of the topic.
2. Lead images should be selected to be of least shock value; if an alternative image exists that still is an accurate representation of the topic but without shock value, it should always be preferred. For example, using an image of deportees being subjected to selection as the lead image at this version of Holocaust is far preferable to the appropriate images that appear later in the article that show the treatment of the prisoners or corpses from the camps.
3. Sometimes it is impossible to avoid the use of a lead image with perceived shock value if the topic itself is of that nature, for example in articles on various parts of human genitalia. It should be anticipated, through PhysicsWiki:Content disclaimer, that readers will be aware they will be exposed to potentially shocking images when navigating to articles on such topics.

### Life cycles of images

Eventually, some of the images reach the end of their life cycle. They may be superseded or replaced by an image with a friendlier copyright policy. If you come across an image that needs to be removed due to copyright, invasion of privacy, or other serious reasons, then list it on Files for deletion. However, superseded images should be kept to preserve PhysicsWiki's historical record. The history of articles can be difficult to assess if images and templates have been deleted over the years.

Conversely, if you have contributed or found an image that stands out from the crowd, you are invited to nominate it for inclusion on the Featured pictures list.

## Image preferences

Logged in users can set their default viewing size of thumbnails in the "my preferences" area under "appearance", which offers an opportunity to customize "files". The default size for users that are not logged in is 220 pixels. Logged in users can choose from widths between 120px and 300px. Also under "files" in the "appearance" tab of "my preferences" area, one can set the size limit of images shown on image description pages. By default, if either the width or the height exceeds 800px or 600px respectively, then the image is reduced in size until it fits within those dimensions. This can be enlarged.