Problem with file not reponding to Photoshop Adjustments ie Levels

[ozworldz]

I have a jpg that does not respond to adjustments. For example if I lighten the file using Levels, the effect shows up while adjusting but when I hit OK it reverts back to being dark with only about a 5% change. It's like a dark film is laid on top of it. It is a scan from a printed book so it is dots. I've tried copying, different formats etc but it acts the same way. 

Help! and thanks.

[lambiloon]

Hi try to convert image to smart object then apply effects on this and try...regards

[Earth Oliver]

You're probably zoomed out, which can result in rendering issues that aren't accurate. You'll need to zoom in at 50 or 100% and then make your adjustments there.

[ozworldz · Accepted solution]

Solution found, the problem is the halftone. Thanks to lambiloon and Earth Oliver for suggestions. 

I tried Smart object but the adjustments menu is not available for the smart object.

Tried zooming as suggested but no go.

SOLUTION (or workaround, if you will) 

It seems to be an issue with halftones. I searched for how to get rid of halftones so I used Filter/Gaussian Blur and found a radius that removed the halftone but left the photo unblurry. After doing this the adjustments worked!!

WOW, just learned something new!!