Can I highlight the texts in the PDF with all image format?

Some PDF pages are all in image format. Can LibreOffice highlights some texts in the PDF with image format? If the answer is YES, how can I do it?

As you have noted, PDF in LO (Draw component) is considered an image. Consequently, you have no tools similar to those of Writer: character styles, highlighting tool, background colour, …

As a fallback, you can add rectangles in the foreground and paint the interior with the desired colour. Don’t forget to set the transparency so that you can see the text through.

An alternate way is to use PDF viewers. Many of them allow to annotate and highlight portions of text. I use Okular for that on my Linux/KDE box.

(You didn’t mention your OS, so I can’t suggest ad hoc applications. If you want to give more details/information, edit your question or comment my answer. Don’t use an “answer” which is reserved for solutions.))

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Sorry but when a pdf it’s opened in Draw-LibreOffice, images in pdf are images in LO, but if there is true text in the pdf are opened in Text boxes and it is editable, not like in writer but can be edited even apply stiles.

Thank you so much for the information. My OS is Microsoft Windows 10. Rectangle and paint is an alternate way. I am still looking for a simply way to do the same.

This is not a solution, Please, make it a comment after my answer. In a Q&A site, answers are automatically reordered by order of relevancy (higher upvoted first, then most recent first). Consequently, the chronological order is lost and we can’t rebuild the time thread easily. This is confusing for users.