PS Techniques for blurring studio backdrops?

[tituspowell]

Hi guys, I'm competent with Photoshop but one thing has been bugging me, and I'd love to get your input.

I have a studio and often use a gray seamless paper backdrop. Often there's marks and wrinkles in the paper when I've been too lazy to cut off a used section! Rather than editing out any imperfections in the paper backdrop, what I'm looking for is a way to create a large blur effect on the backdrop in a photo using Photoshop, and get rid of them that way.

Clearly a case for Gaussian Blur. However, I find that applying Gaussian Blur on a gradient background creates a weird banding effect, with swirly contour lines. Example photos below.

Has anyone else come across this and found a solution? I initially thought it was something to do with JPEG compression, but PS consistently does it even to a RAW file.

Example of one of my photos with a gradient effect on the backdrop:

Close up of the banding effect created when doing a large Gaussian Blur:

Any ideas for how to do a large blur with no banding artifacts would be much appreciated!

 

[Paul MR]

Filter - Blur - Average should give a smooth background.

 

[Tyke Tiler]

Close up of the banding effect created when doing a large Gaussian Blur:

Any ideas for how to do a large blur with no banding artifacts would be much appreciated!

Hmmm, I get this every now and again as well mate, I always thought that it was related to working in 8 bit though? Or sRGB? :shrug: (see here, and here)

I'll standby and hope to be educated too

Some say it's only an artifact seen on screens and will not manifest itself in print, I have seen it on my screen but then it's never been present in the published image.

This may be a question for our own pxl8, a very knowledgeable gent when it comes to things like this.

(Nice shot BT )

 

[tituspowell]

Thanks for the replies...

Filter... Blur... Average isn't what I'm looking for, as I'm not trying to obliterate the gradient itself, just any blemishes and irregularities in it.

Gaussian Blur does exactly the right thing, except for the damn contour lines it for some reason adds!

Would love any more suggestions if anybody knows a smoother alternative method...

 

[photon]

Isn't Average Blur after Gaussian OK?

 

[rdh]

Try lens blur (CS4) mate, you can simulate a shallow DoF and the result can be pretty smooth. Quick mask (or any other kind of feathered selection) before you run the filter.

 

[pxl8]

Not enough bandwidth is the problem. 8bit means 256 shades and the eye can easily tell the difference between each. The answer is either to work in 16bit and convert down later or, the method I use, is to add a little noise to the selection after the blur - just enough to hide the banding.

edit to add: If you look at the original you'll see there was some noise to start with, the blur smoothed it out making it easy to see each step in the gradient - the more gentle/subtle the gradient the worse the problem becomes.

 

[Tyke Tiler]

Not enough bandwidth is the problem. 8bit means 256 shades and the eye can easily tell the difference between each. The answer is either to work in 16bit and convert down later or, the method I use, is to add a little noise to the selection after the blur - just enough to hide the banding.

Your a gent

 

[dcash29]

Have a look HERE

Dave

 

[tituspowell]

Thanks guys, much appreciated.

Dave, that page that link opens is red flagged by my McAfee SiteAdvisor.

 

[natjag]

I use filter>noise>median (or something like that selection)

 

[LongLensPhotography]

Always edit and save as TIFF or PSD files, not JPEG. I am sure this is pretty obvious, but I thought I would mention this. 16bit should help

 

[jayeshpp]

If I were you I would just clean up the background using the Healing Brush and/or Clone Tool, It'll look much better then blurring I think.