Image objects contain information about the generated images. This information includes things such as width, height, filename, absolute path, etc. Images objects also have the ability to crop the image that they reference and return information about the baseline of the image that can be used to properly align the image with surrounding text.
filename is the input filename of the image.
config is the “images” section of the document configuration.
width is the width of the image. This is usually extracted from the image file automatically.
height is the height of the image. This is usually extracted from the image file automatically.
alt is a text alternative of the image to be use by renderers such as HTML.
depth is the depth of the image below the baseline of the surrounding text. This is generally calculated automatically when the image is cropped.
longdesc is a long description used to describe the content of the image for renderers such as HTML.