best method of cleaning this up?

[sleerfnivek]

I've run into this frequently over the years and I'm just finally getting around to asking. 

I'm working on cleaning up an image which was resized from a smaller image. Here's part of it.

As you can see, there are curved lines and straight parallel lines. 

To clean it up I've tried a number of things over the years... select color range, pen tool, curvature tool, and other such things. I've tried painting selections as well. I've probably done it a dozen different ways but I can't escape the feeling that I'm putting far more effort into it than I need to be. 

So I thought I would ask here... what's the easiest method to clean this up so that it has nice, clean lines?

[Trevor.Dennis]

How did you upsize the original image?  If you could share some or all of that image, we might be able suggest a method that requires less clean up.

[sleerfnivek]

I'm not at home right now but I'll upload the entire image when I get home. It was originally a 600 ppi scan of a drawing that he downsized to 72 ppi to use as a desktop icon but rather than save as another file name he just saved it. So he torched that file and lost the original over the years. The rest of the image is easy enough. Mostly straight lines...

I'm not so concerned with this image in particular as I am with the methods used in cleaning up this specific type of shape... I guess it would be a curved parallelogram? Lol

As I said, I've run into this type of shape several times over the years. I've pretty much only used Photoshop for photography where there's rarely a need for clean lines so I never bothered to figure out a quick solution. It's not critical here either as I probably won't do anything like this again for quite a while. I'm just curious about what methods others use for such things that may be less time-consuming than what I've done in the past.