Olá, @roberta.a.page. In all cases, you need to consider the actual conjugation or verb form that is being used in the sentence. In “Eu digitalizo-os”, the verb is conjugated in the 1st person singular, ‘digitalizo’, so there is no consonant to drop and the clitic pronoun doesn’t need any modification. Same for “Eu vejo-as”.
The infinitive form is only relevant if that is the exact form being employed in the sentence. For example:
Eu vou digitalizar os livros → [Eu vou digitalizar-os] → Eu vou digitalizá-los