The Combine function is reducing the quality of my images signficantly

[teloscientist]

I create a series of scan ned text images at 225 dpi.

When I add the image to Acrobat and combine it into a document, the quality of the image deteriorates dramatically.

on the left in the image below is the original image at 400%. on the right is the image after combining it in an Acrobat document (no other work done yet). Note that it has degrated dramatically.

What causes this? How do I fix it?

Thanks!

[Luke Jennings3]

If you are referring to the graininess around the type, that looks like jpeg artifacts, which could be caused by compressing the pdf or converting to RGB.

[try67]

What image format did you use?

[teloscientist]

The images are in .PNG format.
The image on the left is the png image opened for viewing. It looks exactly the same in Acrobat when I "add" the file.
The image on the right is that same image in Acrobat IMMEDIATELY after using the "combine" command in Acrobat.

[try67]

Go to Edit (or the Acrobat app menu, since you're on a Mac) - Preferences - Convert to PDF - PNG and click "Edit Settings". Then set all the Compression options to Quality: Maximum / Lossless.