"Government's view of the economy could be summed up in a few short phrases: If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it."
- Ronald Reagan
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Query Failedmark
Sunday, September 27, 2009

in my opinion all camera's should already been hdr capable!
it's weird it's not developing really, Fuji is really the only one.

from a display perspective i understand, as tft displays are for 88% only 6bit panels why have a wider range image file for the mass market?
Overlord
Thursday, September 24, 2009

Well technically all light sensors are analog, usually they have a photosensitive surface and a form of capacitor or capacitive material.
If you increase the capacitance over area you increase the theoretical dynamic range.
All of this is pretty linear (save for the extremes and possibly part of the upper range) though i can't tell you how the A/D converter does things, but i imagine its spaced reasonably linear or as humus suggested.

And yes my camera can output AdobeRGB as well as sRGB and of cause raw, though the former is more or less useless.
Humus
Wednesday, September 23, 2009

Well, the output in the form of a jpeg image is going to be in sRGB, like any normal image. I think some cameras can use another color profiles, but the difference wouldn't change much. I'm not sure what kind of response curve the average sensor has though. I would tend to think it's not linear, but more like a 2^(-k * light) curve or similar, like for film.
Sean Barrett
Wednesday, September 23, 2009

Do cameras actually output sRGB? I have no idea.
Humus
Wednesday, September 23, 2009

Overlord, actually, the eye can detect smaller differences than 8bit. For a colored gradient it may be hard to detect, even if it's possible, but for a grayscale 8bit gradient the banding is pretty obvious. If you tried the 10bit sample in the August 2009 DirectX SDK you see a very clear improvement going from 8bit to 10bit, assuming your monitor does not truncate the 10bit to 8bits. Apparently my HP LP3065 is able to use all 10bits and the difference was plain as a day and I had to screenshot it to verify that there really was only a difference of 1 between the bands in the 8bit image.

Sean Barrett,
a "stop" in photography is a factor of two. So 200,000:1 would be 17.6 stops. However, the power of 2.2 is really just an approximation of sRGB. The real formula uses a linear part at the bottom and an offsetted power of 2.4 curve for the rest. So for the lowest non-zero value you have (1/255)/12.92, which then gives the dynamic range as about 3300:1, or about 11.7 stops.
Sean Barrett
Tuesday, September 22, 2009

Overlord: gamma-corrected 8-bit at a 2.2 gamma has a range of values from 0^2.2 to 255^2.2. Ignoring the zero for the dynamic range calculation, the effective range is 1^2.2 to 255^2.2, which is a dynamic range of about 200,000:1.

I don't know a 'stop' is a measure of, but 200,000:1 is obviously between 17 and 18 powers of two, and it's well over the range identified by Debevec in his original HDR paper of the things he considered HDR -- in other words, existing 8-bit imagery met his definition of HDR.

The actual problem is that there just isn't enough precision in the darks; if you tone-mapped them brighter you'd see all sorts of crap.

Which is my point: I'm not saying 8-bit imagery is good enough. I'm saying if you're going to make these side-by-side comparisons, there's other interesting comparisons to make instead of just showing a blown-out 8-bit image.
Overlord
Tuesday, September 22, 2009

@Sean "There are two important aspects to HDR - more precision and tone-mapping"

Well not precisely, Dynamic range is defined as the range between the darkest non black color and the brightest non white color detectable, on my D200 it's about 9 stops, increasing precision does increase the usable dynamic range slightly, especially in the dark areas, but it's still in the same general range.

and tone mapping is the process of transforming light in an HDR image to fit a LDR image, it's has nothing else to do with HDR, in fact you could tonemap a HDR to HDR and LDR to LDR.
But you don't have to.

So basically HDR is when you get an dynamic range much closer to that of our eyes, about 15-20 stops or so would do.

So i wouldn't say that the F200EXR is especially that much HDR, but it is a step in the right direction, i mean i could probably do most of the compensation in the above picture if i shoot raw and then fiddle with it a bit, but that takes a lot of work.

And about 8bit, well it's ok for normal monitors since anything more gradual than that is not possible to detect with our eyes, but that is assuming a maximum dynamic range of about 1:500(9 stops) like all lcd monitors have, if you go way beyond that, you will need HDR.
Wes
Tuesday, September 22, 2009

You might be interested in this work:

http://graphics.stanford.edu/projects/camera-2.0/

Where the group is "building an open-source camera platform that runs Linux, is fully programmable (including its digital signal processor) and connected to the Internet, and accommodates SLR lenses and SLR-quality sensors".

The sensor is from the N95 cell phone, so I would guess its not an HDR sensor. Still, its pretty cool work.
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