Assign alternate text to images
Portions of content that are not themselves text - like images, or figures, charts, drawings, etc. - should be accompanied by text based content that reflects the content of it as perceived by sighted users. Getting such alternate text right is a science in its own regard - and sometimes the subject of heated discussion bordering on religious wars. A good guideline is the following: imagine you are talking to a friend over the phone, who is really interested in an article because it is about one of his favorite topics. You have already read the article text to him, but he also wants to understand what images and drawings are shown. The same amount of information you would tell your friend is probably just the same amount of information you should put inside the alternate text of an image - your friend does not want to stay on the phone endlessly, and somebody using a screen reader or some other tool does not want to listen to a thesis about just an image.
Provide alternate text through "Object Export Options..."
Select the frame for which you want to provide alternate text, then use "Object Export Options...".
Go to "Tagged PDF" and choose "Based On Object" and "Custom"
Then enter suitable text in the multiline text field.
Enter suitable alternate text
While you are at it - do the same for "Alt Text"
This "Alt Text" is used for export to HTML and EPUB.
Tip: "Object Export Options" behaves like a panel - just keep it open while working on alternate text for images
The "Object Export Options" window is not a dialog that has to be closed each time alternate text has been entered for an image frame, but rather can be kept open. It will reflect the information for a currently selected frame.
Note: Because there is no OK or Cancel button for the "Object Export Options" be careful when changing information. While the InDesign wide "Undo" feature still works, it is very easy to get lost once you have assigned the wrong text to an image frame, and only realize a few editing steps later.
Images without alternate text - Find them all in one go!
In the MadeToTag panel, choose the "Problem locator" called "Locate images without alternate text", then click "Execute".
Step through all images without alternate text - fix as you see fit
The "Locate images without alternate text" Problem locator lets you walk through all images for which MadeToTag does not find alternate text.
Enter alternate text
... and click "Fix" once done with the alternate text for the currently selected image.
Note: If you enter alternate text for an image, but do not click on "Fix", the text will be lost once you click on "Next" or "Previous" or close the dialog.
Note: A future version of MadeToTag will have a feature that lets you easily review the alternate text for all images in a document.
Use Stylized Preview to double check your alternate text entries in context
Once done with assigning alternate text to all images, just call up the Stylized Preview again by using the keyboard shortcut "Cmd-Shift-V". You will find the alternate text next to the respective image.