Description:
This attribute specifies the alignment of text following the IMG
reference relative to the graphic on screen. LEFT and RIGHT specify
floating horizontal alignment of the image in the browser window,
and subsequent text will wrap around the image. The other options
specify vertical alignment of text relative to the image on the
same line.
Values: Left | Right |
Top | Texttop |
Middle | Absmiddle |
Baseline | Bottom |
Absbottom
Alt
2 | 3
| 3.2 | 4
| IE1 | M2
| N1 | O2.1
Required? Yes
Description:
This is text to be displayed in place of an image for browsers that
can not handle this ability or for browsers that have disabled this
ability.
Description:
This controls the thickness of the border around the image (in pixels)
whether as a hyperlink or as a stand-alone image. If the image is
stand-alone, the border color will usually be the color of the surrounding
text (affected also by the TEXT attribute to the BODY element.) If the image
is within a hyperlink the border color will the default hyperlink color
(affected also by the LINK/VLINK attributes to the BODY element.)
Values:0, for no border, or a positive integer pixel
value.
Controls
2 | 3
| 3.2 | 4
| IE2 | M
| N | O
Required? No
Description:
This standalone attribute specifies a set of video controls be
available to the user in order to allow the user the ability to pause,
stop, re-start or skip parts of the video. It is used in conjunction
with the DYNSRC attribute.
Values: NA
DynSrc
2 | 3
| 3.2 | 4
| IE2 | M
| N | O2.1
Required? No
Description:
This attribute specifies the URL of an in-line video.
Description:
This attribute explicitly specifies the height of the graphic in pixels.
It is mainly used to create custom image dimensions without physically
changing the image itself. It can also be used to speed up display of
the document being downloaded so it can pre-render the document with
image placeholders while the images download.
Values: Positive integer pixel values
HSpace
2 | 3
| 3.2 | 4
| IE1 | M
| N1 | O2.1
Required? No
Description:
This attribute specifies the horizontal spacing around images in pixels
(left and right side padding.)
Values: Positive integer pixel values
ISMap
2
| 3 | 3.2
| 4 | IE1
| M1 | N1
| O2.1
Required? No
Description:
This is a stand-alone attribute which is used in combination with a
hyperlink to identify the image as a sensitive map. When used in
combination with a hyperlink whose destination is a coordinate map
file, the browser sends the coordinates clicked on by the user to
the map file for processing.
The map file is a series of shape names with associated coordinate
values that list corresponding URLs to jump to when the coordinates
are received.
Values: NA
Longdesc
2 | 3
| 3.2 | 4
| IE | M
| N | O
Required? No
Description:
This attribute specifies the URL of a longer description of the image
specified in the SRC attribute. This would allow long passages of
descriptive narrative with markup to be used for image descriptions.
Values: Either an absolute or relative URL.
Loop
2 | 3
| 3.2 | 4
| IE2 | M
| N | O2.1
Required? No
Description:
This attribute specifies the number of times the video will play.
This attribute is used in conjunction with the DYNSRC attribute.
Values:
Specified as a positive integer, or Infinite
(or -1) which will play the sound indefinitely.
LowSrc
2 | 3
| 3.2 | 4
| IE4B1 | M
| N1 | O
Required? No
Description:
This attribute specifies the URL of a low-resolution image to be
downloaded before a higher resolution image. The reasoning is that a
low-resolution image is smaller in size than a higher resolution image
and is thus faster to download. After the lowres image has been
downloaded, it is displayed until the high resolution image is
downloaded.
Values: Either an absolute or relative URL.
Name
2 | 3
| 3.2 | 4
| IE4 | M
| N3 | O3
Required? No
Description:
This attribute is used to give a unique label to this image
so that it can be referenced and manipulated with scripting code.
Values: Alphanumeric characters.
Src
2
| 3 | 3.2
| 4 | IE1
| M1 | N1
| O2.1
Required? Yes
Description:
Indicates the URL to reference the graphic.
Values: Either an absolute or relative URL.
Start
2 | 3
| 3.2 | 4
| IE2 | M
| N | O
Required? No
Description:
This attribute specifies when the video will start playing. This
attribute is used in conjunction with the DYNSRC attribute.
Values: Fileopen
[The video starts as soon as it is finished loading] Mouseover
[The video should start playing when the user moves the mouse
over the video clip.]
Suppress
2 | 3
| 3.2 | 4
| IE | M
| N4 | O
Required? No
Description:
Image placeholders, ALT attribute content
Values: True [Suppress image placeholders and ALT content] False [Do not suppress image placeholders and ALT
content - DEFAULT]
UseMap
2 | 3
| 3.2 | 4
| IE1 | M2.1
| N2 | O2.1
Required? No
Description:
This attribute specifies the URL (usually internal to the document) of
the client-side image map specification to be used if the browser has
that capability. If the argument to USEMAP begins with a "#"
it is assumed to be in the same document as the IMG element. This attribute
is well used in conjunction with the ISMAP attribute for browsers that
cannot understand client-side image maps. Client-side coordinate
mapping is done by the browser, so is inherently faster in processing
the coordinates than the ISMAP process. The presence of a USEMAP
attribute overrides the effect of an anchor (A) element surrounding the
IMG element.
Values: An absolute or relative URL
or an internal anchor name.
VRML
2 | 3
| 3.2 | 4
| IE2 | M
| N | O
Required? No
Description:
This attribute specifies the URL of an inline VRML world. Use of this
attribute will launch a VRML viewer if one is installed on the machine.
Values: An absolute or relative URL
VSpace
2 | 3
| 3.2 | 4
| IE1 | M
| N1 | O2.1
Required? No
Description:
This attribute specifies the vertical spacing around images in pixels
(top and bottom padding.) Values are specified in positive integers.
Description:
This attribute explicitly specifies the width of the graphic in pixels.
It is mainly used to create custom image dimensions without having to
physically change the image itself. It can also be used to speed up
display of the document being downloaded so it can pre-render the document
with image placeholders while the images download.
The ALT attribute is now a required attribute in HTML 4.0. In
previous versions it was not. While the attribute is not necessary
for rendering the specified image, it is good practice to always
provide an ALT attribute - it allows the element to degrade
gracefully on browsers that do not support images or have them
turned off.
If you decide to use any of the Internet Explorer specific IMG
attributes, ALWAYS use an alternate SRC attribute as well to
allow for graceful degradation on browsers that do not support these
attributes (which is every browser but Internet Explorer.)
The ALIGN attribute has two sets of orthogonal behavior types
bundled together: Floating horizontal alignment and in-line vertical
alignment relative to surrounding text. There really doesn't seem to
be a need to specify both types because in each situation, the other
type of attribute is not necessary.
Never specify a LOWSRC attribute without specifying a SRC attribute.
Specifying a BORDER of 0 on an image embedded in a hyperlink may
confuse users who use this attribute to visually identify hyperlinks.
Try to use the USEMAP attribute in conjunction with the ISMAP
attribute, if possible. ISMAP is more widely supported and this solves
the backward compatibility problem.
If you use the ISMAP attribute, always remember to include an
alternate navigation method for users that are not using an
image-capable browser.
If you use a Width or Height attribute alone without the other
attribute, the image will be scaled at the same aspect ratio based
upon the provided single attribute.
Tip: Always remember that a page high in image content can take
quite a long time to load depending on the power and speed of the
connection, equipment and network load. People can become impatient
and stop downloading in such cases, thus your page will never be read.
Strive to control the physical size and quantity of images in your pages.
FAQ: What is the
'NATURALSIZEFLAG' attribute that can
sometimes be found in HTML documents? Quick
Answer: An unnecessary attribute added by the Adobe SiteMill/PageMill
HTML editors. A more in-depth
answer has also been compiled.
Browser Peculiarities
Support Note: Mosaic supported the BORDER,
HEIGHT and WIDTH attributes to the IMG element in the Macintosh
3.0 Betas, but retracted it for its final PC version.
Internet Explorer and Netscape also seem to support a value
for ALIGN called 'center'. This value gives the same results as
the value of 'middle' which vertically aligns the centerline of
an image to the centerline of the surrounding text. Best bet is
to use the legal value of 'middle'.
Internet Explorer 3.0 and above, and Netscape 1.0 and above
also support percentage values for the HEIGHT and WIDTH attributes.
Some older browsers may not support the floating capabilities
offered by the ALIGN attribute (such as Mosaic versions below 3.0)
Vertical alignment relative to the line is historically much more
widespread.
Netscape has never supported external IDs/URLs in the USEMAP attribute
to the IMG element as per the specification (only internal anchors can
be used.) Internet Explorer supports external IDs/URLs from version 1.0
to 3.0, now it does not support them. Opera has supported external
IDs/URLs since version 3.0.
Thought you might like to know: All
the browsers surveyed also support another form of this element (which
is not a part of ANY HTML standard.) The string
"IMAGE" can replace "IMG". Internet Explorer supports
this since version 1.0, Mosaic since at least 2.1, and Netscape since
version 1.1. Internet Explorer did not support this in v4.0 Beta 1
(presumably because the parser/rendering engine for 4.0 was re-built
from scratch), but the strange syntax is again recognized in 4.0 Beta 2.
If an image is used as an image map in a document, the coordinates
specified in the AREA elements must represent the coordinates on
the image AS IT WILL BE USED in the document. Eg: if different
HEIGHT and/or WIDTH attributes are specified in the IMG element the
map coordinates must reflect this. Take care - if percentage heights
and widths are specified, it will be almost IMPOSSIBLE to
give accurate coordinates in the client side image map. This warning
applies to all browsers surveyed that support client-side image maps.
Netscape does not seem to adjust the dimensions of an image if a
LOWSRC attribute is also supplied, ie: The dimensions of the LOWSRC
image are used to render the SRC image if no other HEIGHT and WIDTH
properties have been set.
Setting either of the WIDTH or HEIGHT attributes to zero does strange
things. In Netscape 4, this causes the image to be displayed at its
natural dimensions. In Internet Explorer 4 the image disappears. The
odd thing is, in previous versions of these browsers the behavior
is reversed.
The SUPPRESS attribute in Netscape 4 appears to be somewhat buggy, but
it does appear to work. One of my tests tried suppressing placeholders
with WIDTH and HEIGHT also specified, and the behavior failed. Be sure
to test this behavior well before you use this attribute in pages you
author. For official reference on this attribute, see
http://developer.netscape.com/docs/manuals/htmlguid/tags8.htm.