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Author Topic: Grain in post processed Jpeg images  (Read 6196 times)

RMichael

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Grain in post processed Jpeg images
« on: August 27, 2007, 07:26:14 AM »

Hi


I shoot in JPEG and post process in Photoshop CS2. I find that after processing, applying  things like curves, auto levels etc, the resized image has grain that was not there in the original.Is there something I am doing wrong? How can I prevent it? Will be grateful for any help.







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mahleu

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Grain in post processed Jpeg images
« Reply #1 on: August 27, 2007, 08:21:06 AM »

Shooting in RAW will help a lot as will shooting at a lower iso. Otherwise you can use the noise reduction filter in PS, making sure you check the 'remove jpeg artifact' box. Or you can use seperate software such as noise ninja.
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Lisa Nikodym

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Grain in post processed Jpeg images
« Reply #2 on: August 27, 2007, 11:27:30 AM »

Do you mean that the resizing step itself introduces grain, or that the sum total of steps from the original introduces grain?  If the latter, then is the grain mainly in the darker areas?  With digital images, darker areas tend to be grainier than lighter areas, but the grain isn't so visible when they're dark; however, if part of the post-processing is lightening the image, the graininess in the dark areas becomes much more visible when they are lightened.  Could that be what you're talking about?  If so, there are two ways to reduce it: (1) expose as far to the right as possible, so your dark areas aren't too dark (and hence grainy) to begin with (only possible when the scene's dynamic range isn't too much), or (2) use a tripod to take multiple shots at different exposures, one for the highlights and one for the shadows (which won't be too dark then), and blend them in PS later.

If the graininess is most visible in the sky or other relatively uniform-color regions, one way to make it less visible is to select just that region and then apply a Gaussian Blur filter to smooth out the graininess.

Lisa

RMichael

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Grain in post processed Jpeg images
« Reply #3 on: August 28, 2007, 03:24:28 AM »

Thanks mahleu.

Lisa, I am talking about sum total of all the effects. It also occurs when I try to watermark and then flatten an image. Would you know of some technique of watermarking that a novice could use? Then again, why would a novice need watermarking :-). I'd be grateful nevertheless.

I am still learning both my camera and photoshop, so it would really help if you could show me  how to blend different exposure photos in Photoshop, or if you know of some tutorial.



Thanks and Regards
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RMichael

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Grain in post processed Jpeg images
« Reply #4 on: August 28, 2007, 03:32:46 AM »

Mahleu, I have a problem with RAW. I wonder if you or someone could help me with it. I have a Pentax K10 d and when I open a RAW shot in photoshop, it opens in the Pentax browser. Is there anyway to open it in Adobe Raw? I am not very familiar with photoshop though.




Thanks and Regards
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Lisa Nikodym

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Grain in post processed Jpeg images
« Reply #5 on: August 28, 2007, 12:10:06 PM »

Quote
I am still learning both my camera and photoshop, so it would really help if you could show me how to blend different exposure photos in Photoshop, or if you know of some tutorial.

Right here on this web site:
http://www.luminous-landscape.com/tutorial...-blending.shtml

Quote
Would you know of some technique of watermarking that a novice could use?

Sorry, I've never tried watermarking - anyone else here???

Lisa

francois

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Grain in post processed Jpeg images
« Reply #6 on: August 28, 2007, 12:30:05 PM »

Quote
Thanks mahleu.

Lisa, I am talking about sum total of all the effects. It also occurs when I try to watermark and then flatten an image. Would you know of some technique of watermarking that a novice could use? Then again, why would a novice need watermarking :-). I'd be grateful nevertheless.

I am still learning both my camera and photoshop, so it would really help if you could show me  how to blend different exposure photos in Photoshop, or if you know of some tutorial.
Thanks and Regards
[{POST_SNAPBACK}][/a]
Russell Brown has a Watermarking video tutorial ([a href=\"http://www.russellbrown.com/tips_tech.html]here[/url] - scroll to "Digital Watermark Branding") or you could try to google for photoshop watermarking actions...
« Last Edit: August 28, 2007, 12:31:02 PM by francois »
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Francois

mahleu

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Grain in post processed Jpeg images
« Reply #7 on: August 28, 2007, 01:37:04 PM »

Quote
Mahleu, I have a problem with RAW. I wonder if you or someone could help me with it. I have a Pentax K10 d and when I open a RAW shot in photoshop, it opens in the Pentax browser. Is there anyway to open it in Adobe Raw? I am not very familiar with photoshop though.
Thanks and Regards
[a href=\"index.php?act=findpost&pid=135912\"][{POST_SNAPBACK}][/a]

Try manually opening it from within photoshop (file>open).
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RMichael

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Grain in post processed Jpeg images
« Reply #8 on: August 31, 2007, 06:59:31 AM »

Thanks Francoise, Lisa and Mahleu. It's been a great help.








Regards
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Raycj

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Grain in post processed Jpeg images
« Reply #9 on: September 17, 2007, 08:32:25 PM »

When you save your work, try saving it as a TIFF file. Since JPEG files are compressed, if you save your work as a JPEG you are compressing a compressed file and that can sometimes lead to a grainy look.
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