image

Darwin Information Typing Architecture (DITA) Version 1.3 Part 2: Technical Content Edition

version
1.3
author
OASIS DITA Technical Committee

Use the image element to include artwork or images in a DITA topic.

The image element has an optional placement attribute that indicates whether the included graphic or artwork is rendered inline (a button or icon) or on a separate line for a larger image. There also are attributes that indicate the size to which the included graphic or artwork is scaled.

An image element specifies an href attribute, a keyref attribute, or both. When both keyref and href are specified, the href is used as a fallback when the key reference cannot be resolved. The image addressed by the keyref or href is brought into the main flow of the content as rendered.

To make the intent of the image more accessible for users using screen readers or text-only readers, authors should include a description of the image content in the alt element.

Content models

See appendix for information about this element in OASIS document type shells.

Inheritance

- topic/image

Example

<image href="bike.gif" placement="break">
  <alt>Two-wheeled bicycle</alt>
</image>

Attributes

The following attributes are available on this element: Universal attribute group, outputclass, keyref, and the attributes defined below.

href
Provides a reference to the image. See The href attribute for detailed information on supported values and processing implications.
scope
The scope attribute identifies the closeness of the relationship between the current document and the target resource. Allowable values are local, peer, external, and -dita-use-conref-target. See The scope attribute for more information on values.
height
Indicates the vertical dimension for the resulting image display. If necessary, the image SHOULD be scaled to the specified size. The value of this attribute is a real number (expressed in decimal notation) optionally followed by a unit of measure from the set of pc, pt, px, in, cm, mm, em (picas, points, pixels, inches, centimeters, millimeters, and ems respectively). The default unit is px (pixels). Possible values include: "5", "5in", and "10.5cm". If a height value is specified and no width value is specified, the width SHOULD be scaled by the same factor as the height. If both a height value and width value are specified, implementations MAY ignore one of the two values when they are unable to scale to each direction using different factors.
width
Indicates the horizontal dimension for the resulting image display. If necessary, the image SHOULD be scaled to the specified size. The value of this attribute is a real number (expressed in decimal notation) optionally followed by a unit of measure from the set of pc, pt, px, in, cm, mm, em (picas, points, pixels, inches, centimeters, millimeters, and ems respectively). The default unit is px (pixels). Possible values include: "5", "5in", and "10.5cm". If a width value is specified and no height value is specified, the height SHOULD be scaled by the same factor as the width. If both a height value and width value are specified, implementations MAY ignore one of the two values when they are unable to scale to each direction using different factors.
align
Controls the horizontal alignment of an image when placement is specified as "break". Common values include left, right, and center.
scale
Specifies a percentage as an unsigned integer by which to scale the image in the absence of any specified image height or width; a value of 100 implies that the image should be presented at its intrinsic size. If a value has been specified for this image's height or width attribute (or both), the scale attribute is ignored.

It is an error if the value of this attribute is not an unsigned integer. In this case, the implementation might give an error message and might recover by ignoring this attribute.

scalefit
Allow an image to be scaled up or down to fit within available space. Allowable values are yes, no, and -dita-use-conref-target. If, for a given image, any one of height, width, or scale is specified, those attributes determine the graphic size, and any setting of scalefit is ignored. If none of those attributes are specified and scalefit="yes", then the image is scaled (the same factor in both dimensions) so that the graphic will just fit within the available height or width (whichever is more constraining).

The available width would be the prevailing column (or table cell) width - that is, the width a paragraph of text would have if the graphic were a paragraph instead. The available height is implementation dependent, but if feasible, it is suggested to be the page (or table cell) height or some other reasonable value.

placement
Indicates whether an image should be displayed inline or separated from the surrounding text. The default is inline. Allowable values are: inline, break, or and -dita-use-conref-target.
alt (DEPRECATED)
Alternative text that describes the image to provide accessibility to page readers or provides a text description when an image cannot be displayed by the user's software. The alt attribute is deprecated; use the alt element instead.
longdescref (DEPRECATED)
A reference to a textual description of the graphic or object. This attribute supports creating accessible content. See The href attribute for detailed information on supported values and processing implications. For examples of how this attribute is used in output, see this topic on long descriptions. NOTE: This attribute is deprecated in favor of the longdescref subelement to this element.