Extracting images cause loss in clearness?

[adoberocks]

Hi! I used a customed action to extract all the images from a PPT file. It worked properly for a while, but recently, I found that some of the images extracted are somehow blurry. The following is my setting for that action:

I compared one same image extracted by this action and by "save as" option in PPT.

Extracted one:

"Save as" one:

I know how to get all the images from PPT out by zip, but I still want it to work in Acrobat since this is part of my document processing and they're better to manage if all together. Could someone help me out on this issue please? Thank you very much!