Dan Margulis Applied Color Theory
JPEG Artifacting and How to Cure It
Date: Thu, 14 Aug 2003 14:19:14 +0100 (BST)
From: Alain Corf
Subject: Jpeg artifacts and such like
Does anyone have a definitive method for defeating jpeg artifacts and/or bitmapping in heavily scaled up images?
I have tried various methods with varying results but would like to know if there is a good all rounder to remedy this.
Thanks,
Alain Corf
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Date: Thu, 14 Aug 2003 10:03:11 -0600
From: "Les De Moss"
Subject: Re: Jpeg artifacts and such like
There are several programs based on fractals that deal with this. Do a search on: jpeg fractals. I have an article (somewhere in my office) that lists several. I'll post if I find it.
-Les
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Date: Thu, 14 Aug 2003 08:56:17 -0700
From: David Cardinal
Subject: RE: Jpeg artifacts and such like
I have been using Dfine from nik for JPEG artifact removal. Whether it is the definitive solution you want I don't know, but it does seem to help.
--David Cardinal
Pro Shooters LLC
http://www.proshooters.com
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Date: Thu, 14 Aug 2003 15:33:42 -0600
From: Robert Magnell
Subject: Re: Jpeg artifacts and such like
We've been using Dfine from nik as well and find it quite useful.
We've been using Extensis pxl Smartscale as well and that has beenproductive too.
Robert Magnell
Graphics Technician
Western Producer Publications
www.producer.com
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Date: Thu, 14 Aug 2003 11:25:55 -0700
From: Jim Donovan
Subject: RE: Jpeg artifacts and such like
hello david, have you had any images with jpeg artifacting to the extent looking like a set of stairs around the image, i mean real bad stepping. wonder if dfine can smooth out thoose stairs??
thanx jim donovan
I have been using Dfine from nik for JPEG artifact removal. Whether it is
the definitive solution you want I don't know, but it does seem to help.
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Date: Thu, 14 Aug 2003 14:54:14 -0700
From: FLASHPIX PRODUCTIONS
Subject: Re: Jpeg artifacts and such like
Robert,
Which one gives better results?
Amyn Nasser
<http://amynnasser.com>
We've been using Dfine from nik as well and find it quite useful.
We've been using Extensis pxl Smartscale as well and that has been
productive too.
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Date: Thu, 14 Aug 2003 14:50:38 -0700
From: David Cardinal
Subject: RE: Jpeg artifacts and such like
From: Jim Donovan
hello david, have you had any images with jpeg artifacting to
the extent looking like a set of stairs around the image, i
mean real bad stepping.
I sure haven't. Nik now has a demo of Dfine available though, so it might be possible to see how well it can do, but at the point where you have that much data loss it may not be possible to get back to something acceptable. The artifact correction algorithms can account for some of the error terms & the 8x8 blocking, but if the image was over-compressed to the point where a lot of the original data was thrown away in the rounding and quantization process then it's hard to "guess" what was there in a reconstruction algorithm.--David
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Date: Fri, 15 Aug 2003 08:18:08 -0400
From: "Susan E Hoffman"
Subject: Removing JPG artifacts
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Date: Fri, 15 Aug 2003 11:03:42 -0600
From: Robert Magnell
Subject: Re: Jpeg artifacts and such like
For the most part we use Dfine for reworking the overcompressed jpegs along with some channel blurring in Photoshop. (Sometimes using several channel blends as well) Dfine is very adept at reducing moire in jpegs. I used it yesterday on a big pic of a denim jacket. The jacket had a very distinct red moire in the weave of the denim due to the compression. Running it twice through Dfine in different modes made a huge difference.
We work with a fair bit of highly compressed, generally small farm machinery shots taken with cheap digitals and then compressed yet again giving them the bad stair stepping that was referred to. We still haven't found a decent way of killing off the severe stair stepping.
Sometimes we live by the saying "garbage in, garbage out." As long as it doesn't look worse than when we first opened it, right Dan M.?
Pxl Smartscale is in use primarily on those wonderful images that are supplied right off websites primarily for client advertising. It does an adequate job of scaling without adding to the jpeg woes, we do however run them through Dfine and use other tweaks and channel blends to achieve some sense of normalcy.
We print on newsprint so the massive gain we experience tends to help, rather than hinder badly compressed images.
I hope this helps,
Robert
Western Producer Publications
www.producer.com
Adobe Photoshop training classes are taught in the US by Sterling Ledet & Associates, Inc.