I am building html reports using R Markdown which I intend to publish to a website. My reports contain several data visualizations in both table and graph format. I want to insure the content is accessible to everyone, consequently, i need help designing screen reader friendly visualizations.
For my tables I am using the gt package and keeping structure simple. The output appears to a me (a total novice) to be reasonably accessible. Are there other packages producing better output for reading devices?
For my figures I am using ggplot. markdown processes them into png files. I can add alt text to the image using
fig.cap=" " in the chunk header. However, when rendered this string is added below the .png and displayed in the html output (as a caption). I am interested in adding alt text that remains invisible to all but a screen reader, unless the image fails to display. Is there any way to add this "traditional" alt text to a figure in markdown? I would like to add a description of the figure or a small table summarizing the figure accessible to a screen reader, while not adding redundant signal for sighted consumers.