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Archive 2012 · New Olympus OM-D announced
  
 
kwalsh
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p.3 #1 · p.3 #1 · New Olympus OM-D announced


wjmeyer wrote:
One last thought, is there a difference between jpg and RAW files when using your above "read" vs. "quantization"?


Yes, definitely. JPEG is all about quantization as well, but it isn't quite so simple as it is with a linear RAW file.

In the RAW example the point was we quantized at the point there was no more information available from the sensor. Finer grained quantization would only measure noise more accurately, not provide any more information about scene detail. It was all about recording everything the sensor could "see".

JPEG doesn't really care about noise at all, it is based on a model of what humans see, not what the sensor sees. As a result it actually throws away a whole bunch of valid information from the sensor on the basis that a human won't be able to tell the difference. JPEG does two transformations of the data to achieve this efficiently.

First, it goes from RGB to whats called YCbCr - basically one luminance channel (Y) and two chrominance channels (Cb and Cr) - sort of like the LAB color space in Photoshop. It does this because human vision is much more sensitive to luminance information (tones) than it is to chrominance (colors). So the algorithm can throw away a lot of the Cb and Cr data without us noticing. Noise reduction algorithms work the same way, you can heavily filter the chrominance channels and viewers won't notice so much. It also transforms the data from linear to a gamma curve (more levels at lower values, fewer levels at higher values) which also matches how we perceive images.

Next, it transforms the data from the spatial domain to a frequency domain (think numbers not based on their position but instead on different scales of detail over an area, one number represents the finest detail, the next slightly larger detail and so on). It does this because we are much more sensitive to coarse detail than fine detail so it can heavily quantize (round, throw away data) on the highest frequencies (finest detail) while preserving more data from the lowest.

So there is plenty of quantization going on in JPEG - that quantization is the whole basis of its efficient "lossy" compression, the quantization is the "lossy" part. The difference is what is "acceptable" quantization has nothing to do with what the camera can "see" but rather what the viewer can "see". Most cameras have very high quality JPEG settings available and this lets us still zoom in big and not see a big loss in detail, and do some post processing with no ill effects. But the whole compression model is based on our vision and more extreme post processing breaks the whole premiss. Probably the worst one is doing a B&W conversion from a JPEG with fairly strong channel mixing/selective color conversion. This directly takes chroma data (which is very heavily compressed in JPEG and which we normally can't perceive well) and translates it into luminance data (which we do see very well and now the previously "invisible" chroma compression artifacts become obvious).

Fundamentally there is a limit in how high we can turn up the "quality" knob in lossy JPEG compression - their will always be sensor information left behind and we'll notice it we apply heavy PP to the file. If, on the other hand, there will be no PP applied to the file the information "lost" in the JPEG algorithm isn't visible and so no harm done.

From this you can understand why RAW is far more preferable for image capture (it captures all the information the sensor recorded with no implied rendering intent that might result in information being thrown away) but JPEG is actually just fine for sending to the print house (by definition the final output is for a human viewer so the compression model is perfectly sound).

Well, that was very long winded for a short question. I guess the short answer is that quantization on a RAW file is based on the limits of what the sensor could see where as the quantization on a JPEG files is based on the limits of what we can see.

Ken



Feb 08, 2012 at 05:55 PM
wjmeyer
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p.3 #2 · p.3 #2 · New Olympus OM-D announced


Thank you very much for the excellent explanations Ken, that is how I learn and appreciate you taking the time. You have helped explain what I have struggled to understand for some time now. Thank you


Feb 08, 2012 at 06:00 PM
pr4photos
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p.3 #3 · p.3 #3 · New Olympus OM-D announced


Loving the look of this!!!


Feb 08, 2012 at 06:23 PM
mawz
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p.3 #4 · p.3 #4 · New Olympus OM-D announced


Hmm, maybe Sony will copy this idea for a retro-styled mirrorless body. I wouldn't mind a (NE)X-700 ;-)


Feb 09, 2012 at 12:15 AM
Pixel Perfect
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p.3 #5 · p.3 #5 · New Olympus OM-D announced


plasticmotif wrote:
OMG it looks so nice.


No, it's OM-D; get it right



Feb 09, 2012 at 01:09 AM
Pixel Perfect
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p.3 #6 · p.3 #6 · New Olympus OM-D announced


alexandre wrote:
Last week I thought I'd love to afford one of these but I got pretty sad with the f/6.3 max aperture of the 12-50 zoom in the tele end... and 0.58x viewfinder also sucked big time... maybe I'll change my mind till my birthday or xmas but for now my first option is still E-PM1, kit and Pana 20, thanks.


The VF magnification on the EM-5 is 1.15x and 100% coverage. Sounds good to me. The 12-50 however holds less than zero interest for me.



Feb 09, 2012 at 01:17 AM
wjmeyer
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p.3 #7 · p.3 #7 · New Olympus OM-D announced


I'd pay a bit more if it were a 12-50 f/4 Hey, where are those Panasonic f/2.8 X zooms, I thought they were supposed to be officially announced soon?


Feb 09, 2012 at 01:29 AM
Jman13
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p.3 #8 · p.3 #8 · New Olympus OM-D announced


Pixel Perfect wrote:
The VF magnification on the EM-5 is 1.15x and 100% coverage. Sounds good to me. The 12-50 however holds less than zero interest for me.


Its 1.15x using a 50mm lens as the reference. But micro 4/3 cameras should use a 25mm lens for the reference. It's the same size as a 0.58x full frame viewfinder, and the GH2 has one the size of a 0.7x viewfinder, or about the same size as most full frame finders.



Feb 09, 2012 at 02:20 AM
alexandre
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p.3 #9 · p.3 #9 · New Olympus OM-D announced


Jman13 wrote:
Its 1.15x using a 50mm lens as the reference. But micro 4/3 cameras should use a 25mm lens for the reference. It's the same size as a 0.58x full frame viewfinder, and the GH2 has one the size of a 0.7x viewfinder, or about the same size as most full frame finders.


Help me here Jordan, I'm right when I say this VF is roughly as small as a Canon Rebel one?



Feb 09, 2012 at 03:40 AM
Jman13
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p.3 #10 · p.3 #10 · New Olympus OM-D announced


It should be a little larger than the viewfinder in the Rebel T3i. That's listed at 0.85x, but again with a 50mm lens, so you need to divide by the crop factor to compare...the Rebel has a 0.53x viewfinder with its normal. A little smaller than the Olympus at 0.58.


Feb 09, 2012 at 03:54 AM
 

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Spyro P.
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p.3 #11 · p.3 #11 · New Olympus OM-D announced


viewfinder size = viewfinde _magnification * (1 / crop factor)

why do the give us the VF size as a fraction of something and they dont give it to us in absolute inches or cm I have no idea. It works for televisions.



Feb 09, 2012 at 05:12 AM
Jman13
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p.3 #12 · p.3 #12 · New Olympus OM-D announced


They could even keep it as a magnification number if they would just use magnification with a normal lens for the system. Since 35mm cameras use a 50mm lens for reference...base the VF mag off of an equivalent lens in FOV.


Feb 09, 2012 at 11:16 AM
Desmoface
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p.3 #13 · p.3 #13 · New Olympus OM-D announced


Pre-Ordered the black/12-50. Now the wait begins.

Steve



Feb 09, 2012 at 01:44 PM
wjmeyer
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p.3 #14 · p.3 #14 · New Olympus OM-D announced


Hey, more info I picked up off 43rumors...

PenAndTell (Click here) impressions in german. The administrator is a known figure close to Olympus Europe. Interesting, he writes: “whats new? [...]the sensor: compared to the E-P3 there is aprox. 1,5EV less noise and 0,3 more dynamic range. and NO, it isn’t another “spiced up” Panasonic sensor!”

Very interesting about the sensor, is this just their opinion, or do they truly know? It seems foolish that Olympus would try and create almost the exact same sensor that Panasonic already has so I have my doubts about the above.

They also write:
the humpback has several functions: it defines the OM-D line. It increases the distance of the flash to the optical axis. And it is home to four sensors, including two of the new sensors for the IS. (Acceleration and a second gyro sensor).

So for those of us wondering why it is so big, here is our answer, it's not just the EVF that is in there, it's a bunch of other electronics as well.

Also interesting is the info about Live Bulb, I'll have to look more into that, and something that I have not seen before is the shutter lag:
The delay is - hold on - 29ms. So 0.029 seconds.

The D700 shutter lag was 45ms I believe, so I would think this to be more than sufficient

Finally, I like the remark about the roadmap for future Oly MFT lenses from 43rumors:
Seventh news: “Currently we are focused on fast primes but it would not surprise me to see some fast zooms down the road.”



Feb 09, 2012 at 10:38 PM
kwalsh
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p.3 #15 · p.3 #15 · New Olympus OM-D announced


I think that delay spec is actually for the EVF lag, not the shutter lag. We'll see eventually I guess!

Ken



Feb 09, 2012 at 10:44 PM
wjmeyer
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p.3 #16 · p.3 #16 · New Olympus OM-D announced


Hi Ken, hmmm, you might be right... darn, maybe I got a little too excited there


Feb 09, 2012 at 10:48 PM
hauxon
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p.3 #17 · p.3 #17 · New Olympus OM-D announced


wjmeyer wrote:
Hey, more info I picked up off 43rumors...



I just finished reading this and am glad that the adapted 4/3 lenses focus fast, little slower than when mounted on E5 but still fast. ...one might start looking out for something like the 50-200mm f/2.8-3.5 ED.



Feb 10, 2012 at 10:47 AM
Jman13
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p.3 #18 · p.3 #18 · New Olympus OM-D announced


The new 75/1.8 looks sexy:








Feb 10, 2012 at 11:01 AM
hauxon
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p.3 #19 · p.3 #19 · New Olympus OM-D announced


It's a beauty!


Feb 10, 2012 at 11:09 AM
wjmeyer
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p.3 #20 · p.3 #20 · New Olympus OM-D announced


Jman13 wrote:
The new 75/1.8 looks sexy:

http://dc.watch.impress.co.jp/img/dcw/docs/510/854/032.jpg


That's what I'm really looking forward to, one of my most favorite portrait lenses was the 135 f/2 L from Canon, it just has a certain "look" to it, and I'm hoping this beauty will also have that "look" or better. If the 45mm f/1.8 is any indication I think we can expect amazing results from this lens!



Feb 10, 2012 at 02:36 PM
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