Need a little help in PP.

I took this image from a tripod as part of a timelapse I did back in April. It was a little bit after dusk, with a 1st quarter moon rising to the FAR left of the image, therefore brightening the front of the barn. My question is this: Are there any programs I can use to decrease the amount of trailing present in the picture? It was a 90 second exposure. I'm planning on entering the image in a county fair as part of the landscape/skyscape portion. Do you think the trailing would be detrimental to the image?

I know the above image is dark, but I also have a version that has star trails and is much brighter as well. Uggghhhhh, I hate choices.

Elizabeth, give this a try. It's a process a friend, Bud Guinn came up with. Bud's an amazing astrophotographer and a really great guy.

• In PS duplicate the image layer(called a background copy), next change the background copies blending mode to darken. In your image you'll want to work only on the sky so you can erase the lower part(just above trees down) of the layer you just created.
• Next with background copy high lighted, select the offset tool in filters - Filters>Other>Offset. (zoom in 500% on the image "Ctrl +") and adjust the horizontal/vertical pixels. Undefined areas set to wrap around). For the full size(hi rez) picture use Horizontal of "0" and Vertical of "13"...this will very depending on the size of the trails and what direction they are heading....i.e. up and down...on a 45....sideways....etc.​....play with the two settings until the trails are diminshed or eliminated....you can use negative numbers.
• Once the star shape is where you want it, zoom back out. Then flatten the image and save.

This may be all that you want to do, but you also might want to smooth and soften the sky out a bit......usually when you remove trails or fool with them abit they become somewhat pixelated....so try the following to smooth and soften the stars.

• Start with a flattened image
• Duplicate the background layer. (you should now have two layers)
• Now use the magic wand and select the stars. (tolerance about 40..anti-aliased not contiguous). You can select a bright star with the wand and then go to select>similar. The brightest stars will be selected, the dimmer ones will have to be selected manually with the wand.
• Use the shift key to select more of the stars.
• Now Select>Modify>Expand....about 2 or 3 pixels
• Now Select>Feather....about 3 pixels
• Filter>Blur>Gaussian Blur....about 1 pixel
• Select>Modify>Contract....by the same amount that you expanded...2 or 3 pixels
• Now you can adjust the hue and saturation if you like...Image>Adjustments>Hue/Saturation...adjus​t to your satisfaction.

This will soften the stars and make them abit less pixelated.

I made some adjustments on your star trail version using curves in PS, and I also reduced a bit of the saturation from the trees down to give a more starlight feel.

I understand the the offset moves the image, but when I use it in GIMP, it does not shift the pixels. Well, I guess it does, but it does ALL the pixels, so they don't look diminished at all. I'm using the settings you are, but I guess I don't get it....

Apparently, I don't know how to merge layers, either. GRRRRRRRR.

Apparently also, when I make layers, I don't know how to separate them right. I'm beginning to hate GIMP.

OK, got the layers thing figured out, but the offset STILL doesn't work. I give up.