Web Accessibility Checker : Check Details

Element

img

Error Type

Potential

Guidelines

BITV 1.0 (Level 2)
Level 1
3.1 When an appropriate markup language exists, use markup rather than images to convey information.
WCAG 1.0 (Level AA)
Priority 2
3.1 When an appropriate markup language exists, use markup rather than images to convey information.
WCAG 1.0 (Level AAA)
Priority 2
3.1 When an appropriate markup language exists, use markup rather than images to convey information.

Requirement

All img elements with images containing math expressions have equivalent MathML markup.

Error

Image may contain math statements.

Short Description

This error is generated for all img elements that have a width and height greater than 100.

How To Determine

Question	Does this image contain any math statements that are not described in the document?
PASS	Image does not contain any math statements that are not described in the document.
FAIL	Image contains math statement that is not described in the document.

Steps To Check

Procedure

1. Check each img element in the content.
2. Discern if there are any math expressions in the image.
3. If the image does contain a math expression then check the content for MathML markup that is equivalent to the math expression.

Expected Result

1. All img elements with images containing math expressions have equivalent MathML markup.

Failed Result

1. Provide MathML markup for all images containing math expressions.

Examples

Pass Examples

Image contains math and document has MathML.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1 plus MathML 2.0//EN" "http://www.w3.org/TR/MathML2/dtd/xhtml-math11-f.dtd" [
  <!ENTITY mathml "http://www.w3.org/1998/Math/MathML"> ]>
<html lang="en">
	<head>
		<title>Testfile - Check #135 - Negative</title>
	</head>
	<body>
		<p>The following image shows the solution to the quadratic equation: begin fraction minus b plus or 
			minus begin square root of b squared minus four a c end square root over 2 a 
			end fraction</p>
		<img src="quadeqn.png" alt="solution to the quadratic equation" width="179" height="63">
		<math xmlns='http://www.w3.org/1998/Math/MathML'>
			<mfrac>
				<mrow>
					<mrow>
						<mo>-</mo>
						<mi>b</mi>
					</mrow>
					<mo>&pm;</mo>
					<msqrt>
						<mrow>
							<msup>
								<mi>b</mi>
								<mn>2</mn>
							</msup>
							<mo>-</mo>
							<mrow>
								<mn>4</mn>
								<mo>&it;</mo>
								<mi>a</mi>
								<mo>&it;</mo>
								<mi>c</mi>
							</mrow>
						</mrow>
					</msqrt>
				</mrow>
				<mrow>
					<mn>2</mn>
					<mo>&it;</mo>
					<mi>a</mi>
				</mrow>
			</mfrac>
		</math>
	</body>
</html>

Fail Examples

Image contains math but document has no MathML.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/REC-html40/strict.dtd">
<html lang="en">
	<head>
		<title>Testfile - Check #135 - Positive</title>
	</head>
	<body>
		<p>The following image shows the solution to the quadratic equation: begin fraction minus b plus or minus begin square root of b squared minus four a c end square root over 2 a end fraction</p>

		<img src="quadeqn.png" alt="solution to the quadratic equation" width="179" height="63">
	</body>
</html>