Jpeg artifacts on a night sky?

Hello. I took some pictures of the lunar eclipse the other night and after uploading to my site, I noticed horrible blocky jpeg artifacts (I guess that's what they are). Any way to get rid of these other than reducing noise and using the brush tool to black them out? Ugh...the pictures were nice til I uploaded them. Here's an example: http://www.pbase.com/n​gannet/image/131311047 and an even worse one here: http://www.pbase.com/n​gannet/image/131311049 Some of the others have this as well. Most noticeable when looking at the screen from an angle. Any tips would be appreciated. Thanks.

If you see any detail in the black sky, your screen is way too bright. (Assuming the images are sRGB, there's no embedded profile)

What browser?
How do the images compare in your browser vs. in Photoshop (or whatever editing software you use)?

Yep, this is a screen problem, not an image one.

René Damkot wrote in post #11507834
If you see any detail in the black sky, your screen is way too bright. (Assuming the images are sRGB, there's no embedded profile)

What browser?
How do the images compare in your browser vs. in Photoshop (or whatever editing software you use)?

The images look similar in PS CS4 as they do in Firefox browser. When I use the brush to brush over the 'lighter' parts of the black sky, I can see the difference. I think you instructed me about color settings a while back, but here is what I have for color settings in case it matters. The photos were all shot in high quality JPEG.

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I'd agree that your monitor brightness must be set too high.

It's true that if you brighten dark areas too much you will show things...ugly things because of noise in underexposed images that is handled in different ways by different cameras -- and sometimes if you look at an image at an odd angle artifacts can be more obvious, but with a black sky you don't want your brightness cranked up. If you can see artifacts, you are a prime candidate for lowering your screen brightness.

When looking on my laptop screen at an angle, I can see some artifacts. But those should not be visible on a properly calibrated screen when viewed at the proper angle.

PS color settings are good, and if the image looks the same in FF and PS, that's good too

tonylong wrote in post #11511077
I'd agree that your monitor brightness must be set too high.

It's true that if you brighten dark areas too much you will show things...ugly things because of noise in underexposed images that is handled in different ways by different cameras -- and sometimes if you look at an image at an odd angle artifacts can be more obvious, but with a black sky you don't want your brightness cranked up. If you can see artifacts, you are a prime candidate for lowering your screen brightness.

Can you see all 26 bars on this chart? If not, time to adjust brightness/contrast.

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Number 6, I can see all the 26 bars. By the way everyone, the monitor is/has been actually set on the LOWEST brightness setting:/ Still see the 'artifacts'. I guess I just have to live with it.

ngannet wrote in post #11514885
Number 6, I can see all the 26 bars. By the way everyone, the monitor is/has been actually set on the LOWEST brightness setting:/ Still see the 'artifacts'. I guess I just have to live with it.

Hmm -- maybe if you boosted the exposure or shadows shadows until they are really noticeable and then posted a crop showing just some of those artifacts we may have better ideas of what you are dealing with?