Recently I have been getting very grainy skies in my pictures and cant seem to get rid of the grain using blur on CS4. Furthermore this only happens with skies, blue or orange. Anyone have any ideas as to why?

check out a) your ISO setting and b) noise ninja

what is noise ninja?

legalhack wrote:
Recently I have been getting very grainy skies in my pictures and cant seem to get rid of the grain using blur on CS4.

Strange. Digital skies that seem to exhibit grain-like artifacts suggest image noise. Hard to believe blur won't remove grain-like artifacts. Might help to know the details and see an example.

BTW, Noise Ninja is one of the software tools available to reduce image noise.

Antipode, for example...

First, I have no trouble blurring the images. However, that generally isn't the proper method to deal with the noise in the images. Unfortunately without the EXIF info and an understanding of your workflow, I can't conjecture why they have such a high noise level. However, when I've encountered this before it's often been with under-exposed images that were pushed to recover a lighter density - trying to mine image data from shadows.

What you need to apply is Filter>Noise>Reduce Noise and then fiddle with the sliders. However, that can also somewhat trash the image detail. My preferred method to remove the noise but retain the detail is to make a duplicate layer and apply the Reduce Noise filter to the duplicate layer. Then I erase the duplicate layer over the detail area.

Here's a section of the red sky scene made using the above Reduce Noise duplicate layer with the ground portion of the duplicate layer erased. The next image if the skyline with a Reduce Noise duplicate layer with the buildings erased, applied twice.

legalhack wrote:
tried again with cs4 and it doesnt seem to want to blur anything! agh!!!!!

If you can't blur *anything* it suggests a problem using CS4. How familiar are you with Photoshop? Old hand? Fairly new?

Noise Ninja is one of several widely used, widely respected programs, generally available as plug-ins or stand alones, used to reduce noise. They work well. Others include Nik Dfine, Neat Image. All have free demos to check out.

I too would like to see the EXIF. Its not hard to get rid of most of the noise as AuntiPode has demonstrated. I ran the city image thru Dfine with similar results. I can post if you'd like. Some noise will not show up as readily on prints, partly dependent on your choice of paper.

Scott

The city skyline looks more like pollution than a camera issue.

In the other shots, at least with such small images, it could be as trivial as the JPG compression being set too low. Do you shoot JPG? Are you seeing the problems in the full res images?

Other culprit, as noted, could simply be insufficient exposure followed by overmanipulation in post.

Jim

Grenache wrote:
The city skyline looks more like pollution than a camera issue.


Jim, if you examine the skyline image's sky with magnification, I think you'll agree it suffers from noise more than air pollution. By the same token, I wouldn't expect the color pattern in the sky from jpeg compression, at least not whilst retaining good detail in the buildings without obvious jpeg artifacts:

There is some noise there too, but if you compare the close tree line at the bottom of the image to anything in the distance, including the mottled buidings, I think that you'll see that even though it is darker, it has less noise. That is not how simple underexposure and bad post usually manifests itself.

The buildings are pretty mottled like the sky to me. I'd be interested to see the EXIF data. OP has not responded for a while.

Jim