JPG compression artefacts

[Paul Stam]

I had these two photos rejected. The reason was: JPG compression artefacts.

I looked to the aircraft and saw no artefacts. So I appealed both photos.
Then I got the following message:

Your appeal for photo id 2557937 has been processed and has been rejected.
Admin Comments >> Paul, you can strongly see the effect of compression in the sky. There are edges between the different shades of blue, while it should be one smooth transition.

So I looked again to the photos, equalized them and saw that the screener was right.

As far as I know, I had this never before.

Who can tell me what I can do about these artefacts in the sky?

[seahawk]

Save at the highest quality settings available for jpgs in your software, after starting from the original. In camera set jpg to the best quality settings.

Another useful trick is to open the orignal in your editing software and do the whole editing, then save then finished edit once. Do not open and save again. (Obviously you can open the file, but you should not save it again)

[saupatel]

I only edit my shots once and do all the stuff that Stefan said and i still get some rejections for JPEG compression.

These artefacts puzzle me

[LX-A343]

As far as I know, I had this never before.

You mean, that mail to us following a rejected appeal a week ago was from another Paul Stam?

Anyway, easiest way to avoid JPG compression:
- in you camera select highest quality settings (for example "JPG fine" or so)
- When you start editing the photo, do not save the photo until you've finished all editing.
- At the very end of your editing, save the photo at the highest JPG quality settings or highest JPG quality settings.

That's it basically

[saupatel]

By the way, I shoot in RAW all the time. So before editing, i convert the RAW to JPEG (highest Quality + 300dpi). Would this process create the artefacts in anyway?

[Paul Stam]

You mean, that mail to us following a rejected appeal a week ago was from another Paul Stam?

Ha, ha, yes I am the same Paul Stam. But when this photo was rejected for artefacts, I thought of the airplane. I never looked to the sky. So I edited the photo again and saw no artefacts around the airplane.

I have had never before artefacts in the sky.

And I always save my photos in the highest quality settings.

But I shall try it again

[saupatel]

By the way would any of you be kind enough to show me where the artefacts are on this shot so I can check for it in the future.

http://www.jetphotos.net/viewreject_b.php?id=2556781

thanks in advance
Saurabh