Extract image resolution from pdf using itextsharp in vb.net

How to extract attribute and attribute values from html using regex pattern in c#.Need extract attibute and attribute values from html using regex in same pattern.

example :

How to highlight missed content ,when compare to two pdf using itextsharp in vb.net ?example below

user user quiamen dellaut, nonsed ut restiatatus sequae nonse sumenessi volut quidellenet, cum dolecul liquatium ea corepuditas moluptatus aut eveliti buscimo user user quatem sus planihi lluptatempos dollestrum aperi secum facculles nest aliqui occum quatusam nonectatiam, ssenima ximint quiam dolupid erferum dolorem peribusam ut expeles tiandel ius acestias alibus, que dolo que ni

Second Pdf:

user quiamen dellaut, nonsed ut restiatatus sequae nonse sumenessi quidellenet, cum dolecul liquatium ea corepuditas moluptatus aut eveliti buscimo user quatem sus planihi dollestrum aperi secum facculles nest aliqui occum quatusam nonectatiam, ssenima ximint quiam dolupid erferum dolorem peribusam ut expeles tiandel ius acestias alibus, que dolo que ni

I need highlight user and volut in first pdf,because it has deleted in second pdf and "user" is repeated word in first pdf,so i need highlight user word, and also highlight mismatch contents.How to highlight this using itextsharp in vb.net?Please suggests if any ideas.

You can use Spire.PDF to read the image resolution from pdf.