Alternative Text in Google Docs
To add alternative text to images, right-click on the image, and select Alt Text.
This opens another window to add the alt text title and description. It may be helpful when writing alternative text to close your eyes and write down what you were able to see. One tip, do not include the words “photo of….” or “image of,” as this is not necessary for screen readers to help understand the content.
Charts and Graphs
Ideally for the graphs, you should display the data table below. That way the screen reader users can access the data related to graphs. If that is not possible, you can add alt text. Make sure you include all the relevant information in the alt text. Adding the alt text to the chart/graph is the same procedure as adding the alt text to images. Select the chart/graph, right-click on it and select Alt text.
This opens another window to add the alt text title and description.
It may be helpful when writing alt text for charts and graphs to boil down the idea to the bare essentials — what is this graph used to illustrate? What is the gist of what you are trying to get across by using this chart? Visit the accessible content page to learn more about writing proper alternative text.