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Author Topic: uprezing... at what stage?  (Read 2246 times)
laughingbear
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« on: September 15, 2008, 07:00:10 AM »
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Greetings,

Sorry if this a very basic question, looking at the LL camera to print video I wondered about it.

I understand that you can do certain levels of uprezing in camera raw.

What I do not understand is at what stage you do the rest, say you would really go for 400 percent uprezing if you have a really propper exposure and sharp picture.

So, do you do your photoshop work first, then uprez and then do the final output sharpening?

Any hints to master this are most welcome in deed.

Thanks,
Georg
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01af
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« Reply #1 on: September 15, 2008, 10:29:08 AM »
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When planning to upsize a raw image then neither use Camera Raw's sharpening feature nor Camera Raw's resize feature. Instead, convert it to an unsharpened RGB image at native size and load it into Photoshop.

There, upsize it to the required size using Image > Image Size, resampling method Bicubic Smoother. Then apply sharpening for source or capture sharpening. Then continue with other tweaks and edits. Finally apply sharpening for output, and print.

Using Camera Raw's built-in resizing and capture sharpening features are convenient to use but will lead to inferior results. In particular, the resize feature will add nasty (albeit tiny) ringing artifacts around high-contrast edges. They are not easy to detect but once you found them you'll start seeing them everywhere. They are so tiny you may decide to ignore them as they won't be visible on a print so what the heck? ... yet you should be aware of the issue.

[attachment=8376:attachment]

See the attached image above; click it to see it at full size (560 540 pixels, 51 KB). It's a crop which shows the rim of a back-lit sunflower's leaf against a dark background at 400 % view---so it's a tiny detail at huge magnification. The raw file has a native size of 3,008 2,000 pixels (6 MP). Part A has been upsized to 5,120 3,404 pixels (17.4 MP) and capture-sharpened in Camera Raw 4.5; it clearly shows the ringing artifacts mentioned above. Part B has been converted in Camera Raw 4.5 to 3,008 2,000 pixels unsharpened, then upsized to 5,120 3,404 pixels in Photoshop using Bicubic Smoother, then sharpened for source using Bruce Fraser's method, to match part A visually. Part B has very slightly better detail, and ringing artifacts are absent entirely.

-- Olaf
« Last Edit: September 15, 2008, 10:41:40 AM by 01af » Logged
mistybreeze
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« Reply #2 on: September 15, 2008, 10:56:34 AM »
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Unfortunately, there is no correct "black and white" answer here. The only way to know for sure is to perform a test and analyze the results. Since the answer will be different, depending on the image, an image by image test will be necessary if perfection beyond the human eye is what you seek.

Julieanne Kost, a Senior Digital Imaging Evangelist employed by Adobe, suggests that up-rezzing may be best in Camera Raw while Jeff Schewe (and Bruce Fraser) suggest you do a test of each image to be sure. Schewe claims to prefer results up-rezzing in Photoshop but he has his own process, which includes various stages of sharpening. Will you get the same results as Jeff? Hard to be sure without his eyes.

John Nack has said Adobe needs to get better at informing users, especially pro users, the absolute best way to achieve professional results in Photoshop. I'm not holding my breath on this one.
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01af
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« Reply #3 on: December 03, 2008, 07:23:14 AM »
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Quote from: 01af
Using Camera Raw's built-in resizing and capture sharpening features are convenient to use but will lead to inferior results. In particular, the resize feature will add nasty (albeit tiny) ringing artifacts around high-contrast edges.
Camera Raw 5.2 now has changed the game. It does not create those nasty ringing artifacts upon upsizing anymore, thanks to an improved interpolation algorithm.

-- Olaf
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