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Author Topic: down rezzing  (Read 7397 times)
woof75
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« on: November 03, 2008, 10:31:39 AM »
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With all these super high MP backs coming out are people testing what happens when you down res 200 percent or whatever is needed to make the files correctly sized for 95 percent of all applications. Are there any IQ losses involved doing this?
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rainer_v
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« Reply #1 on: November 03, 2008, 05:52:47 PM »
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Quote from: woof75
With all these super high MP backs coming out are people testing what happens when you down res 200 percent or whatever is needed to make the files correctly sized for 95 percent of all applications. Are there any IQ losses involved doing this?
yes it can damage a file.
i use photozoom for uprezzing and its great for this. for downrezzing it isnt good at all i.m.o.
therefor i use ps "bikubic sharper". huge difference to photozoom. just as example.
« Last Edit: November 03, 2008, 05:53:01 PM by rainer_v » Logged

rainer viertlböck
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T-1000
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« Reply #2 on: November 03, 2008, 06:12:33 PM »
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I agree completely.

PhotoZoom Pro is one hell of a program for upsizing (S-Spline engine), but downsizing can create jagged edges.  Use Photoshop for downrezzing (Bicubic sharper), and apply correct sharpening.
« Last Edit: November 03, 2008, 06:13:49 PM by T-1000 » Logged
Wayne Fox
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« Reply #3 on: November 04, 2008, 12:38:13 AM »
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yeah, it's tough to show a web image from high res camera.  Hard to mash a 39mp PhaseOne image into a 600x400 pixel image.

Of course it's pretty easy to print a really big image, without even uprezzing
I just use Photoshop's bicubic sharper as well, with a quick Smart Sharpen.  Not always happy but not sure if there is a good way.
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Dustbak
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« Reply #4 on: November 04, 2008, 01:11:15 AM »
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Same here. PS with bicubic sharper. I mostly have no need to sharpen afterwards. I would like to know what sharpening others apply when they do sharpen again after downsizing? Not necessarily image quality loss but sure you do lose a lot of the nice details you have which was one of the things you started using a 39MP file
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michele
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« Reply #5 on: November 04, 2008, 02:21:58 AM »
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I use Bicubic in PsCs3... It works very well and you don't need to unsharpen the image. It still have very good smooth passages, if you use USM You'll have an oversharpened image...
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dustblue
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« Reply #6 on: November 04, 2008, 02:40:41 AM »
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Well, I just use Lightroom's export, to whatever size I want, and it even add copyright mark automatically...so, I'm sure I'm just lazy, but the result seems no problem for me. Just my 2 cents.
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Murray Fredericks
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« Reply #7 on: November 04, 2008, 03:03:26 AM »
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I tested bicubic vs bicubic (sharper) in PSCs3 and actually acheived by far the best results with Bicubic for down-rezzing. The key to me was using a very light smart sharpen:

80%
0.3 radius

after the down-rez.

Thats going from a 33mpx file down to web display...

Murray
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BernardLanguillier
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« Reply #8 on: November 04, 2008, 03:29:59 AM »
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Quote from: woof75
With all these super high MP backs coming out are people testing what happens when you down res 200 percent or whatever is needed to make the files correctly sized for 95 percent of all applications. Are there any IQ losses involved doing this?

You might to ask this guy what technique he uses... the downsizing problem he is facing is much tougher...

http://www.yosemite-17-gigapixels.com/

As far as I am concerned, CS3 bi-cubic + Smart sharpen radius 0.2 and strenght 200+% does the trick between 12 and 200 MP.

Cheers,
Bernard
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SeanBK
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« Reply #9 on: November 04, 2008, 05:35:30 AM »
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Quote from: BernardLanguillier
You might to ask this guy what technique he uses... the downsizing problem he is facing is much tougher...

http://www.yosemite-17-gigapixels.com/

As far as I am concerned, CS3 bi-cubic + Smart sharpen radius 0.2 and strenght 200+% does the trick between 12 and 200 MP.

Cheers,
Bernard

   Promises are a plenty prior to Nov4th.
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Graeme Nattress
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« Reply #10 on: November 04, 2008, 07:18:40 AM »
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Bicubic is actually a very poor downsampling filter. I'm bemused at why Photoshop doesn't offer proper ones. Going down a large percentage from a large image you're likely to run into all kinds of aliassing issues with Bicubic. The "old hack" work-around is to gaussian blur the image a bit first to make up for the poor anti-aliassing properties of Bicubic.

That said, there is no one perfect downsampling filter. That's why it's best to have a number of options to choose from.

Graeme
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BlasR
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« Reply #11 on: November 04, 2008, 08:21:22 AM »
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Quote from: BernardLanguillier
You might to ask this guy what technique he uses... the downsizing problem he is facing is much tougher...

http://www.yosemite-17-gigapixels.com/

As far as I am concerned, CS3 bi-cubic + Smart sharpen radius 0.2 and strenght 200+% does the trick between 12 and 200 MP.

Cheers,
Bernard


Bernard,

The Barraca Hussein, paying you for that?

BlasR
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SeanBK
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« Reply #12 on: November 04, 2008, 09:08:29 AM »
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Quote from: BlasR
Bernard,

The Barraca Hussein, paying you for that?

BlasR

Sorry to correct your spelling, but it is spelled Borat. Both have same amount of experience.
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woof75
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« Reply #13 on: November 04, 2008, 01:08:35 PM »
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Quote from: SeanBK
Sorry to correct your spelling, but it is spelled Borat. Both have same amount of experience.

Surely this means that you should match sensor resolution to output size/resolution for highest image quality (baring cropping/artifacts)?
For most work that is appearing in a magazine this would make ideal resolution (including a bit extra for cropping) to be around 18mpx?
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SeanBK
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« Reply #14 on: November 04, 2008, 02:30:17 PM »
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Quote from: woof75
Surely this means that you should match sensor resolution to output size/resolution for highest image quality (baring cropping/artifacts)?
For most work that is appearing in a magazine this would make ideal resolution (including a bit extra for cropping) to be around 18mpx?

Yes, that's what I meant & don't call me Shirley!!
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EricWHiss
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« Reply #15 on: November 05, 2008, 11:58:43 PM »
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Okay - going to set you to ignore from now on.  No point in reading your posts anymore.   I'll bet you didn't even vote or read up on the issues anyhow.  


Quote from: BlasR
Bernard,

The Barraca Hussein, paying you for that?

BlasR
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BlasR
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« Reply #16 on: November 06, 2008, 08:38:26 AM »
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Quote from: EricWHiss
Okay - going to set you to ignore from now on.  No point in reading your posts anymore.   I'll bet you didn't even vote or read up on the issues anyhow.
It's working,     Cup of Tea?
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kikashi
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« Reply #17 on: November 06, 2008, 12:09:34 PM »
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Quote from: EricWHiss
Okay - going to set you to ignore from now on.  No point in reading your posts anymore.   I'll bet you didn't even vote or read up on the issues anyhow.
I make a remark you don't like, so you ignore me thereafter. Democracy in action!

Oh dear.

Jeremy
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jmvdigital
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« Reply #18 on: November 06, 2008, 12:12:22 PM »
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Thread time of death: 11:09 AM MST
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Justin VanAlstyne
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kikashi
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« Reply #19 on: November 06, 2008, 02:43:11 PM »
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Quote from: jmvdigital
Thread time of death: 11:09 AM MST
Its death throes began good few hours earlier than that, I fear.

Jeremy
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