yowgangsta
Topic Author
Posts: 17
Joined: Wed Feb 02, 2005 3:16 am

Help Finding Dust Spots And Grain

Thu Apr 25, 2013 1:47 pm

Over the last year and more recently, I've had several photos rejected for dirty (dustspots) or grain. Things that should be obvious for me before submitting, but for whatever reason I don't see it. Maybe it's a poor monitor calibration or poor monitor altogether.

To clarify, I'm using the healing brush to remove dustspots that I find after equalizing the image, but the artefacts that are left behind are causing the rejections. Here's a couple of examples:
http://www.airliners.net/procphotos/...1365986031.3321acds_0083pr-mbj.jpg
http://www.airliners.net/addphotos/r...1365876690.6292acds_9971cc-cxg.jpg
http://www.airliners.net/addphotos/r...1365730225.7958acds_0166pr-gte.jpg

Maybe it's obvious to others, but I've even had to rework my workflow to do a smart blur to get rid of subtle grain that I don't see. Without that, I'd have a bunch more rejections for grain in dark areas including the sky.

I'm currently using a Viewsonic monitor (http://www.viewsonic.com/us/monitors/vx2453mh-led.html). Dynamic contrast ratio at 30,000,000:1

Curious if anyone can point me to some calibration technics that could help make dust spots and grain a bit more visible. Also would like to know what type of monitor characteristics I should look for the next time I buy one.

Cheers.

[Edited 2013-04-25 06:57:13]
 
vikkyvik
Posts: 11909
Joined: Thu Jul 31, 2003 1:58 pm

RE: Help Finding Dust Spots And Grain

Thu Apr 25, 2013 2:51 pm

Quoting yowgangsta (Thread starter):
Things that should be obvious for me before submitting

They're not always obvious. Can be tough to pick out sometimes.

Quoting yowgangsta (Thread starter):
Curious if anyone can point me to some calibration technics that could help make dust spots and grain a bit more visible

If you're using Photoshop, equalize the image. That will (usually) make dust spots easier to see, and frequently grain, as well. Or, dragging the image around the screen (in circles, or left to right, or whatever) tends to make dust spots and grain much easier to pick out.
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
yowgangsta
Topic Author
Posts: 17
Joined: Wed Feb 02, 2005 3:16 am

RE: Help Finding Dust Spots And Grain

Thu Apr 25, 2013 3:53 pm

Thanks for the response. I do equalize during the dust spot removal. I think part of what creates the problem is the remnants of the healing brush. I just thought those remnants were neglible.

Recently I've adopted cloning with a gradient brush that's giving better results, but it still leaves me with grain in my photos that I need to remove with a smart blur.

Considering my work flow involves level, resize, USM, smart blur, I'm not sure how this grain is polluting my pictures as much as it is when not using the smart blur.
 
vikkyvik
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Joined: Thu Jul 31, 2003 1:58 pm

RE: Help Finding Dust Spots And Grain

Thu Apr 25, 2013 4:35 pm

Quoting yowgangsta (Reply 2):
I think part of what creates the problem is the remnants of the healing brush. I just thought those remnants were neglible.

I find the clone tool tends to work more consistently, since you can pick a region of sky to use to clone out the dust spot. Spot healing tool sometimes works, but sometimes leaves remnants that can be as bad, if not worse, than the original dust spot.

For grain, you might try using some noise reduction on the full-size image, prior to resizing. Of course you can also use NR after resizing, but I'd do it selectively, only on the parts of the photo that need it. I'd be careful using a blur or median tool - the photo could end up with banding or blotchiness, instead of grain.

With that said, obviously the better the exposure, contrast, and sharpness straight out of the camera, the less noise you'll introduce in editing.
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
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Moose135
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RE: Help Finding Dust Spots And Grain

Thu Apr 25, 2013 4:47 pm

Quoting vikkyvik (Reply 1):
Or, dragging the image around the screen (in circles, or left to right, or whatever) tends to make dust spots and grain much easier to pick out.

I've tried that technique a couple of times. All I get is dizzy...

Quoting vikkyvik (Reply 3):
I find the clone tool tends to work more consistently, since you can pick a region of sky to use to clone out the dust spot. Spot healing tool sometimes works, but sometimes leaves remnants that can be as bad, if not worse, than the original dust spot.

I'll usually use the clone tool, but if I end up with a bit of an edge where I've cloned (looking at the equlized image) I'll give it a little touch up with the healing brush.
KC-135 - Passing gas and taking names!
 
yowgangsta
Topic Author
Posts: 17
Joined: Wed Feb 02, 2005 3:16 am

RE: Help Finding Dust Spots And Grain

Fri Apr 26, 2013 12:57 am

Quoting vikkyvik (Reply 3):
Spot healing tool sometimes works, but sometimes leaves remnants that can be as bad, if not worse,

I believe that's what's happening to me.

Quoting moose135 (Reply 4):
I'll usually use the clone tool, but if I end up with a bit of an edge where I've cloned

I think I'll go back to cloning but with a gradient brush, to avoid the harsh transition of where the cloning took place.

Quoting vikkyvik (Reply 3):
For grain, you might try using some noise reduction on the full-size image, prior to resizing.

I never understood the parameters for NR in PS. What do you recommend?
 
vikkyvik
Posts: 11909
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RE: Help Finding Dust Spots And Grain

Fri Apr 26, 2013 4:05 am

Quoting yowgangsta (Reply 5):
I think I'll go back to cloning but with a gradient brush, to avoid the harsh transition of where the cloning took place.

Yes, use a brush with a soft edge rather than hard edge, if that's what you mean. Also, I tend to set the opacity at 80%. That's usually plenty to eliminate visible dust spots, and helps not have as big a transition.

But really, the key is picking a part of the sky for the clone source that matches the area you're cloning over.

Quoting yowgangsta (Reply 5):
I never understood the parameters for NR in PS. What do you recommend?

Well, for NR on the full-size image, which I don't do selectively, I do it on the RAW image. Parameters vary quite a bit depending on the amount of noise in the photo.

For selective NR on the resized JPEG, it's almost always:
strength: 1
preserve details: 0
reduce color noise: 30%
sharpen details: 0

...and it's only applied sparingly to noisy areas, if I feel it's necessary.
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
JKPhotos
Posts: 713
Joined: Wed Nov 09, 2011 4:03 pm

RE: Help Finding Dust Spots And Grain

Fri Apr 26, 2013 12:24 pm

Hi,

concerning the nois reduction I would recommend a plug-in for PS.

I tried PS own version before, but it did not work out too well for me.
Now I am using the "dfine noise reduction" and it works perfectly.

There is a trial version if you want to try it.

Cheers.
 
Thumper45
Posts: 4
Joined: Thu May 09, 2013 3:13 am

RE: Help Finding Dust Spots And Grain

Thu May 09, 2013 10:11 pm

For an image like that there should be no apparent noise unless the equipment is out of date or the settings are wrong.

Shoot as low ISO as you can go, even if that means you shoot for an underexposed image and have to bump the exposure up in PS (shoot in RAW format if you underexpose, it gives you far more margin to adjust the exposure without loosing quality).

As for dust/dirt, the easiest thing to do is take your camera in to get it cleaned. If you are like me ever minute you spend editing is lost time for shooting and making money. $20-50 ever 3-6 months to have the camera professionally cleaned (or you can give it a go yourself if you want to) is well worth it and saves you the hassle of having to edit out junk.
 
vikkyvik
Posts: 11909
Joined: Thu Jul 31, 2003 1:58 pm

RE: Help Finding Dust Spots And Grain

Fri May 10, 2013 4:43 pm

Quoting Thumper45 (Reply 8):

Shoot as low ISO as you can go, even if that means you shoot for an underexposed image and have to bump the exposure up in PS (shoot in RAW format if you underexpose, it gives you far more margin to adjust the exposure without loosing quality).

Underexposure will result in more noise when you brighten it in post-processing, though.
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
RCoulter
Posts: 456
Joined: Wed Apr 11, 2007 5:02 am

RE: Help Finding Dust Spots And Grain

Fri May 10, 2013 5:11 pm

Quoting vikkyvik (Reply 9):
Underexposure will result in more noise when you brighten it in post-processing, though.

Exactly, and some Canons like the 7D you actually to shoot as far to the right of the histogram as you can without overexposing as that can help reduce grain.

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