October 24, 2014, 02:18:52 PM

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Messages - Lee Jay

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61
I was using the picture as an example where the software detects clipping, yet the image is perfectly fine. My bet is that if my camera had a half stop more DR, that I would not have gotten clipping....

Your camera could have had 20 more stops of DR and you would have had the same clipping.  That clipping is based on the rendering of the raw image into Melissa RGB (ProPhoto primary colors with an SRGB tone curve).  Since the tone curve is fixed, more raw DR would make no difference to the clipping warnings when they are generated in this fashion.

62
here is another example from today... as you can see from the histogram, it is run up to the edges on both sides and technically, a bit more DR would have extended detail in the highlights and in the shadows.....

Not true.

That's the histogram for the default conversion, which does not come close to extracting all available DR in the raw data (It's a CR2 file).

You could have large spikes on the left edge and right edge of the default conversion and a lot of clipping showing on both sides and still have plenty of DR left.
Interesting.... I did not know that!

So what conversion works better?

You would have to expose so that only the pixels you want blown in the final are actually blown in the raw data.  That isn't easy.

That will result in you having a lot more blown pixels in the default conversion than you want.  You'll need -exposure or -highlights to get them back.

If there are dark areas you want brighter, you'll need +shadows for them.

The only real way to know if you're bumping up against the DR limits of your shot are to set -5 exposure and see if you still have some solid areas that are bright (those are almost certainly blown in the raw data) and then set enough +exposure and/or +shadows to make the darkest areas at the levels you want them in the final, and then see if they are too noisy for your taste or for you to see the detail you want in those areas.

63
here is another example from today... as you can see from the histogram, it is run up to the edges on both sides and technically, a bit more DR would have extended detail in the highlights and in the shadows.....

Not true.

That's the histogram for the default conversion, which does not come close to extracting all available DR in the raw data (It's a CR2 file).

You could have large spikes on the left edge and right edge of the default conversion and a lot of clipping showing on both sides and still have plenty of DR left.

64
EOS Bodies / Re: Multilayer Sensors are Coming From Canon [CR2]
« on: October 12, 2014, 01:07:19 PM »
I'd jump to buy a camera that had a max ISO of 100 and 1 fp 10 seconds if it offered better resolution and DR.

Get a 7D Mark II and a Gigapan.  In 10 seconds, you can shoot something like a 9 shot panorama with a 5-shot bracket at each spot.  That should get you 16+stops of DR and 115 megapixels.

65
EOS Bodies / Re: Multilayer Sensors are Coming From Canon [CR2]
« on: October 12, 2014, 12:34:05 PM »
I meant with an IR-modified camera or for example with the 60Da

Oh...in that case, roughly the same (give or take a stop or two - not orders of magnitude).

66
EOS Bodies / Re: Multilayer Sensors are Coming From Canon [CR2]
« on: October 12, 2014, 12:00:40 PM »
A few questions pertaining to the usefulness of capturing IR data in a separate channel:
1) Can humans see InfraRed?
No.
Quote
2) How much of the IR spectrum can be transmitted through DLSR lenses?
All of the near IR spectrum.  But little gets through the sensor's IR filter.
Quote
3) Can you gain added colour accuracy by sampling additional channels which overlap with wavelengths outside human visual perception?
I doubt it.
Quote
4) For a given ISO and Aperture, what is the difference in exposure time needed to create an IR image vs a visible light image?
With the IR filter, orders of magnitude

67
EOS Bodies / Re: Multilayer Sensors are Coming From Canon [CR2]
« on: October 12, 2014, 11:40:30 AM »
Your rendering demosaiced data, which doesn't necessarily require the constant memory space.

Yes, it does.  When you're in the Develop module of Lightroom or using Camera Raw, the entire 64 bit per-pixel image is in memory.  The rendered view is on top of that.

68
I have DR problems a lot but that's because I get only get 7-9 stops of DR in many of my shots because so many are at high ISO.

If I had my choice, which I don't because of the quantum nature of light, I'd rather have two more stops of DR at high ISO than at low ISO.

69
EOS Bodies / Re: Multilayer Sensors are Coming From Canon [CR2]
« on: October 12, 2014, 08:51:47 AM »
Quote from: dgatwood link=topic=2316channel 1932#msg4channelste=1413081039
It would also be a tremendous amount of data, and a lot more data to be factored into image processing. Five layers at 25megapixels is 125megaphotodiodes. At 14-bit, that's around 235-245 megabytes per image. RAW editors would also have to add the right kind of support to utilize those extra layers.

Even three layers would be unworkable uncompressed at 25 megapixels per layer.  It's hard enough to deal with 25–30 megabyte image files, much less four times that.  They're clearly going to have to come up with a good lossless compression algorithm.  A lossless scheme similar to PNG should get you about 2.7:1 compression, which means about 81 MB with all five layers included, or 49 MB with only three layers.  But I think it is possible to do better than 2.7:1.  After all, the high order bits of nearby pixels are likely to be fairly similar except near high-contrast edges, and the more bit depth you have, the more identical bits you'll probably have.

Storage space probably isn't nearly as big a concern, as yes, you can compress the files. However when your working on them, you need the full pixel data. It's like opening a large 16-bit or 32-bit TIFF in Photoshop...if you look at the memory usage, it is usually several hundred megs.

So what?  When you're working in Lightroom or Camera Raw you're working on demosaiced data anyway at 16 bits per channel for four channeks.  The size is 8 bytes * pixel count.

70
I wonder if Chipworks will dissect the 7D II sensor. It's been a long time since they dissected a Canon sensor...

Not so.

https://chipworks.secure.force.com/catalog/ProductDetails?sku=CAN-EOS-70D_Pri-Camera&viewState=DetailView

For $16k you can find out everything you want to know.

71
EOS Bodies / Re: 7D2 theory
« on: October 10, 2014, 04:58:17 PM »
To produce stunning images, a professional doesn't need to understand the science of light, they just need to know what works for their images.

Understanding the science would make them better.

72
EOS Bodies / Re: 7D2 theory
« on: October 10, 2014, 11:57:25 AM »
He was talking FILE SIZE.

Then why did he say, "megapixels" instead of "megabytes"?

73
EOS Bodies / Re: Multilayer Sensors are Coming From Canon [CR2]
« on: October 09, 2014, 03:45:59 PM »
I wonder if it would be helpful to have a quasi-bayeresque multi-layer sensor.

So instead of having every pixel being constructed with what I assume would be a B/G/R construction, they decide to have some interspersed pixels with other channel arrangements. (e.g. R/G/B)

Personally, I like Panasonic's color splitting technique. It still preserves all of the light, but it has W-R and W+R pixels (white plus/minus red, which ends up being "bluish" and "reddish" pixels in the end). It doesn't filter at all, it just splits the light coming in and directs some component of it (red) to different pixels. It's supposedly 100% transmission (probably not exactly, 99.something%), and 2-3 times the sensitivity of bayer sensors (which should mean it's far more sensitive than a layered sensor, with high dynamic range and color fidelity:

http://image-sensors-world.blogspot.com/2013/02/panasonic-develops-micro-color-splitters.html

Di and Trichroic filters have been used before, most notably in "3 CCD camcorders".

Sure, but those were pretty bulky, with three full sized sensors. This is a fully integrated per-pixel solution.

You saw this?

http://www.dpreview.com/articles/6555348105/nikonimagesensor

74
EOS Bodies / Re: Multilayer Sensors are Coming From Canon [CR2]
« on: October 09, 2014, 02:56:03 PM »
I wonder if it would be helpful to have a quasi-bayeresque multi-layer sensor.

So instead of having every pixel being constructed with what I assume would be a B/G/R construction, they decide to have some interspersed pixels with other channel arrangements. (e.g. R/G/B)

Personally, I like Panasonic's color splitting technique. It still preserves all of the light, but it has W-R and W+R pixels (white plus/minus red, which ends up being "bluish" and "reddish" pixels in the end). It doesn't filter at all, it just splits the light coming in and directs some component of it (red) to different pixels. It's supposedly 100% transmission (probably not exactly, 99.something%), and 2-3 times the sensitivity of bayer sensors (which should mean it's far more sensitive than a layered sensor, with high dynamic range and color fidelity:

http://image-sensors-world.blogspot.com/2013/02/panasonic-develops-micro-color-splitters.html

Di and Trichroic filters have been used before, most notably in "3 CCD camcorders".

75
EOS Bodies / Re: Multilayer Sensors are Coming From Canon [CR2]
« on: October 08, 2014, 11:21:22 PM »
Guys, is it possible to get 16-bit images with FF DSLRs in theory? Would it give any real life benefit vs. 14-bit?

Yes, and possibly.

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