Removing Graininess from Digital Pictures

[Cheesefood]

My camera and many other digital cameras I've seen is an extreme light-hog. That is to say that it takes beautiful pictures outdoors, but in low-light situations it's had to get a good picture with a speed faster than 1/16 or 1/30.

Many of the indoor pictures I take end up with a lot of red and blue grains in them. Now, the obvious answer is "Use the flash, stupid" but the flash can sometimes overexpose the picture.

Now, being that most of my shots aren't staged, but more family event type situations, a re-sitting isn't an option.

Does anyone have a good technique for post-production grain reduction? I'd love to be able to fix some pictures I have, but I haven't figured out a good panacea.

[Colin Walls]

There is a tool out there that is designed to remove digital noise from pictures. It can be enhanced [more $$$] to be characterised for specific models of camera.

Ah. Found it! Here: <http://www.nikmultimedia.com>

I have not tried it, but it does sound good. If you do try it, please report back here.

The alternative is to get a camera with good low-light performance. Some are well-known for this.

[Cheesefood]

The alternative is to get a camera with good low-light performance. Some
are well-known for this.




My girlfriend bought me the camera for Christmas, and spent $500+ on it. Guilt prevents me from exchanging the present because she spent a lot of time and money picking out the camera. It takes great outdoor pictures, and I'm learning to adjust the flash. The Olympus C-720UZ is a great camera because of the advanced features it offers, but it takes a lot of practice.

I'd like to be able to fix pictures I took before I learned how to properly use the camera, like at her nephew's First Communion.

[Cheesefood]

Just looked at the Nik website. The tool you mentioned looks to remove grain at the cost of focus. Is it just me, or do the after pictures seem blurry?

[dave milbut]

check out <http://www.alienskin.com> for Image doctor. free 30 day full function demo.

also have you tried mathias' denoise actions? they're quite good. i don't have the link here at work... someone please provide?!! :)

I have an olympus 3020 zoom and it takes great in and outdoor pictures. in fact i returned a minolta and a sony because i didn't like either the indoor or outdoor shots. the 3020z does a good job of balancing the quality between the 2 enviornments with minimal fuss. the only bad (not THAT bad) time I have with it is outdoor night shots at a distance (ie parade distance - curb to street).

[Mathias Vejerslev]

Try my free actions for Photoshop:

<http://www.2morrow.dk/75ppi/coolpix/actions/>

[Colin Walls]

Cheese:

Setting the ISO on a digicam isn't like using different film speeds - i.e. 400 is no more "grainy" than 100. It's just a gain setting on the CCD. The sensor has a limited dynamic range - the ISO setting defines the midpoint. So, in low light, using the high ISO is best, with no downside.

Having said this, most cameras have an auto-ISO mode, which means that they choose the gain based on the mean lighting level. Most of the time, this will do the job. You should see the ISO setting in the EXIF data, I think.

[Cheesefood]

Colin:

Thanks for the response. I have found that using the Auto ISO on my camera can yield unpredictable results, so I usually keep it locked on 100. Maybe I should experiment with the Auto some more.

Now, correct me if I'm wrong, but doesn't gain = grain?

[Colin Walls]

You mean does higher gain mean amplifying noise too? Yes, it could do, but this is offset by the benefits of the shift in the dynamic range "window", I believe. With any electronic sensor, the best results come when its sensitivity range matches the range of signals to be detected.

I could, of course, be making all this up. But, in this thread at least, I am being serious. Honest.

[dave milbut]

I could, of course, be making all this up.




hmmm.... :)

[Burton Ogden]

Cheesefood,

In addition to the good suggestions that have already been made, I have a few comments. Low light conditions force your digital camera to apply an increasing amount of electronic amplification. High amplification of a weak signal is inherently noisy.

As others have suggested, your Blue channel will be the noisiest because incandescent light is weakest in that part of the spectrum. The Red channel will have an intermediate amount of noise and the Green channel will have the least amount of noise. (Night vision devices take advantage of that with their green light imaging.)

Several manual and Action-scripted Photoshop techniques work on your channels separately, concentrating on the Blue channel. It can be enlightening to view just your Blue channel (use the Channels palette for that). If your image was JPEG-compressed, in addition to CCD noise you may have the characteristic square artifacts of JPEG to deal with. I prefer Noise> Median over Blur> Gaussian Blur as a treatment for the Blue Channel, and a lesser amount of Median for the Red channel.

Photoshop's Median tends to "melt" and smooth jagged edges while preserving the edges and "swallowing up" tiny specks and other fine details. I use Median quite a lot and hope that Photoshop 8 will have a "Super Median" filter. I have looked in other applications for a better Median filter but so far I have not found one. The Photoshop plugins, Quantum Mechanic Pro and Quantum Mechanic Lite, are Photoshop plug-ins from Camera Bits that elaborate on the Median technique. You might want to experiment with their demos by downloading them from the Camera Bits site.

<http://www.camerabits.com/QM2.html>

I experimented with all of the Quantum Mechanic demos, and I got some reasonably good results, although I have not purchased either plug-in yet. I guess I had hoped for even better results considering the rather high prices of the Quantum Mechanic plug-ins. In my opinion the Quantum Mechanic filters are due for a major upgrade.

I did purchase Acclaim Software's Focus Magic and I use it on most of my digital images. I do a lot of frame grabs from my DV video footage, and most of them seem a bit "out of focus", so they are noticeably improved by Focus Magic. I also use Genuine Fractals on the video frames. Most image "sharpeners" concentrate on the edges of an image, while Focus Magic works on the entire image, using a unique mathematical deconvolution process.

Focus Magic includes two programs, a Photoshop plug-in and a standalone application. Each has its strong points, and they complement each other. You can find out more about Focus Magic and download a demo at:

<http://www.focusmagic.com/>

-- Burton -- (not associated with Acclaim Software or Camera Bits)

[Eric Purkalitis]

This plug-in came out recently, I haven't tried it though.

<http://www.fixerlabs.com/pages/noisefixer.html>

[mike engles]

Hello

NeatImage from Neatimage.com.
Terrific. Works as aplugin in Photoshop otr as a standalone. It has to be learnt.

Mike Engles

[Howard Goldberg]

Check out <http://www.imaging-resource.com/IRNEWS/> for an excellent review of Dfine.

"Feature: Dfine-ing Your Images
Noise. Hard to define, you know it when you hear it. And, if you're a digital photographer, you know it when you see it, too. If tools like Photoshop's Smart Blur have disappointed you, you've probably learned to live with it, much as you did with film grain.
But noise isn't grain. You can do something about it.

Until we played with nik multimedia's Dfine ([url]http://www.nikmultimedia.com/dfine[/url]), a Photoshop plug-in to handle noise and enhance image detail, we didn't really think it was worth doing anything about noise. But now we've got the glow of a seeker of wisdom and truth, as the song goes."

Bob Goldberg
Digimajic
"Where Photography Meets The Future"
[email]goldberg@digimajic.com[/email]