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Old Feb 26, 2004, 11:03 AM   #1
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Default Panasonic Bob - need you opinion on Compression on FZ10

check out this thread here
http://forums.dpreview.com/forums/re...essage=7799097

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by Jack Scholl
Both shots are straight from the cameras with all settings "standard". Could the file size be a factor in this issue? The 750 is 2693kb and the FZ10 is 1329 kb. That sure seem like a big difference for the same shot with 4MP cameras. Any thoughts on this?
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Old Feb 26, 2004, 9:31 PM   #2
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Default Panasonic Bob - need you opinion on

I am in the process of buying a FZ10. I Downloaded your images, very little differance, but as far as I'm concerned the FZ10 is sharper.
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Old Feb 27, 2004, 3:10 PM   #3
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I'm going to try and read through all ofthis over the weekend. The week's been very busy and I've had no time to see how you all are doing. I'd suggest this... If the same photo were taken at perhaps -1/3 EV you might see the missing detail you are concerned about. I've been realizing that often a small change in contrast can give the illusion of more or less sharpness.

Again, forgive me for my brief response but I have avery busy agenda right now. Good weekend.
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Old Feb 27, 2004, 8:06 PM   #4
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If you compare Steveís FZ10 and Oly 750 pictures the Oly files are larger indicating a higher quality JPG compression. I donít think that accounts for the difference in the linked photos though. In the first place there isnít that large a size difference in Steveís sample photos, which I always presumed he takes at the default settings. http://www.steves-digicams.com/2003_...0_samples.html and http://www.steves-digicams.com/2003_...z_samples.html

I blew up some sections of the dpreview photos and the JPG artifacts are actually worse on the Oly 750 shot. I would suspect that is the result of extra sharpening or higher contrast settings. Either that or the Oly really does a poor job of JPG compression despite the larger file size.

Edit: The guy has obviously been screwing with the photos. Take a look at the ones he changed to on the same thread: http://forums.dpreview.com/forums/re...essage=7766471 The FZ10 takes more saturated shots at the default setting and I suspect a metering error or he has just been altering his images to make for a useless heated discussion.
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Old Feb 27, 2004, 9:07 PM   #5
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Here's a suggestion on testing the effects of compression:

First, shoot a picture at ISO 400. On the FZ1/2/10 you should get quite a bit of noise. This is good for our test since the noise is semi-random and therefore the image will be harder to compress.

Now, post-process the image to remove the noise (using Neat Image, Noise Ninja or any other tool).

Now compare the results with another camera. If you only have one, repeat the experiment with a different compression setting.

I suspect that over-aggressive compression will lose more detail so the noise filter will have less to work with and the results will have an unnatural look.

I believe that will be a valid test because:
(a) even if you cannot see the detail difference between the unretouched images, it will have an impact on the post-processing. and
(b) several situations (like indoor action) will require higher ISO sensitivity and subsequent post-processing.
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Old Feb 27, 2004, 9:21 PM   #6
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Quote:
Originally Posted by slipe
I blew up some sections of the dpreview photos and the JPG artifacts are actually worse on the Oly 750 shot. I would suspect that is the result of extra sharpening or higher contrast settings. Either that or the Oly really does a poor job of JPG compression despite the larger file size.
Extra sharpening/artifacts will result in larger file sizes due to incompressibilty.
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Old Feb 27, 2004, 9:24 PM   #7
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I'm "the guy" you are referring to and I can assure you there has been no "screwing with the photos". There may be a meter problem-this is the 2nd new FZ10 as the first one had several problems. But I can assure you there has not been any "altering his images to make for a useless heated discussion". It sure would be helpful if you add constructive observations to any of these issues rather than make unfounded accusations.
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Old Feb 28, 2004, 1:26 AM   #8
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Jack, there are a lot of people who don't understand how JPEG works. They don't understand that more compression relates to more noise and artifacts. I would imagine they also record their MP3's at 16Kb/sec thinking that they will get CD quality. Don't waste your time trying to explain that a "lossey" format throws away, (permanently deletes), image information. It's not a question of image quality, but rather one of brand loyalty. No one wants to believe that the camera they bought is not the best there is, whatever brand that my be.
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Old Feb 28, 2004, 7:07 AM   #9
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Guerito,
The FZ10 pics are roughly 1/2 the size of the Oly 750. Both are 4MP cams. Arguably the 750 has a slight edge on sharpness right out of the camera. Still having trouble reconciling this.
Some have said the increased sharpness in the 750 is a result of sharpening algorithms in the 750, which increases file size. That may well be the answer.

Sure is confusing.

Jack
http://www.pbase.com/jrs40
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Old Feb 28, 2004, 9:21 AM   #10
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Quote:
Originally Posted by jack scholl
Some have said the increased sharpness in the 750 is a result of sharpening algorithms in the 750, which increases file size. That may well be the answer.
Sounds like it to me. What is the compression bits per pixel of the 750? The fz10 is 2.0 Standard and 4.0 Fine.
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