problem with manipulating levels

I have JPG files at 1600x1280 that are set in RBG that when I choose to alter the levels of them, it acts like it's working and then just reverts to looking similar to the original drawing. I say "similar" because it does change slightly, but not like the preview shows.

A little history on what I'm attempting to do....

I have a couple large scale CAD drawings that were provided to me as JPG files. I am saving them for web as a .gif file at 100px to show as a thumbnail. The problem is that because of the thin lines in the CAD drawing, the thin lines get displaced and blurry when I change the size of them, and in the past by changing the levels at high res the lines get preserved in the smaller size. It worked in the past, but for some reason not now. I'm doing the exactly the same thing as before, I don't understand what the problem is.

Did I accidently change a setting maybe? I'm at a loss.

It's amazing how you can feel proficient at your work and the course of events in 2 days have the feeling like you are completely inept.

I'll be anxious to see if anyone has feedback for me.

Thanks a ton...

-b

is it possible to get the file, so i can play with it and see what sup. cause i kind of lost, u cant really save levels settings not that i know about, so thats not a problem, it might be the settings of the image, or something might be selected, or u might be changing levels slightly in one of the channels, but it not it, can you explain in depth. u can try reseting photoshop settings.

does this happen when you save? or right after levels and resize?

i don't know man, the only logical explanation is that some image settings were altered, and that you need to go through mode of the image and bit/chanel, might be profile but i know for sure that leveles act differently depending on the image settings

Thanks for the reply gnrlbzik. I solved the problem, but not by just using photoshop. I took the file into illustrator, and shrank it there. Then saved as a .gif, opened it in Photoshop and wha-la! It worked.

Not sure what the deal was there, but I'll take your recommendation and get reset my settings. I might have done something to it in my haste.

Thanks again!

-Brian

no probs, thanks for replying to my post, people usually dont leave comments : )