Editing colours in two areas

[391615]

I had a photo in the general gallery. the sky was a little too bright. I used the program Gimp, which is a detailed free program similar to the abilities of photoshop. I created a mask, I changed the levels, so the church was dark and the sky was light. I then selected the church. I got back to the original photo. I then changed the brightness and the contrast. It looked good. Then I inverse selected, and edited the sky. I had trouble changing the brightness in the clouds without it looking horrible. Then on closer inspection I had a thin green, or just a line around the whole church. How can I stop this from happening.

 

[The_Traveler]

This is probably because the mask has a very sharp edge.
Try selecting the mask and blurring it; that will allow a transition between light and dark.

You might also post a 100% crop of the image.

 

[stubbsk]

Yeah blur it and then use levels on the mask. Move the mid tone to fine tune the edge.