Are JPG compression artefacts similar to oversharpen?

[Bart Bandy]

I'm still don't really understand JPG compression artefacts. What am I looking for. Will they be reduced in impact if I start with a 2000X 1300 pixel image vs. a 3000X 2000?

http://www.jetphotos.net/viewreject_b.php?id=1494820

This was a bit of a messy image to start with due to a ridiculous number of dust spots. I submitted it because of the special scheme.

Any help gratefully received.

Cheers

[RingwaySam]

Dave,

The plane itself doesn't look compressed, it's the sky - It looks really blochy. Wheather it's to do with the cloning I don't know. If it is, use the Spot Healing tool in PS, it's much easier.

Theres also a glare on the gear...

HTH,
Sam

[Bart Bandy]

Tried to fix the sky using the heal tool. I don't use cloning for sky "repairs". I had a lot of spots on the sky from some adventures with the lens. Still working on correcting that.

Cheers

[justtosim]

Also, the shot was rejected for compression artifacts because the colors from the livery fade too much into the sky. Indeed the sky is looking way too compressed.

The fading colors could have something to do with a too strong noisefilter (like NeatImage) together with a too high compression level.

Simon

[pdeboer]

It seems to me there is a major sharpening problem. Some parts are sharp, some even a bit too (like the star in the tail, the stabilazor and top of front door) whilst other parts are undersharpenend (like the right landinggear and engine, wingtip and the 'belly'). And there is a contrast problem (landinggear).
My advice: try not to improve your processed image, but go back to the original (in large format), work with layers to selectively sharpen and remove noise than resize and, if needed give some extra (selective sharpening). Good luck!

cheers, Pamela