Dynamic Range

"They dynamic range is set by the sensor, electronics, and capture settings."

What about the subject!?!

My point is that increasing dynamic range and bit-depth means reinterpreting the file so that we can see it! This is something we are probably going to have to get used to doing. I agree about the haloing BUT it can be striking and you might well be surprised how many non-photographers like the results. We sometimes have a tendency to photographic political correctness as photographers, in being somewhat staid in our photographic conventions and being a little technocratic if we aren't careful.

Good example, Paul

Can you post some u/w samples? Also do you actually use bracketing u/w and use the outputs for the HDR? Or use few images from the same RAW in different exposures?

"They dynamic range is set by the sensor, electronics, and capture settings."

 

What about the subject!?!

The dynamic range is a characteristic of the imaging system. The signal to noise ratio is a characteristic of a specific image. It depends on the subject and the exposure. I didn't mean to imply that post processing can't improve an image. Of course it can. But "dynamic range" is a very precise concept that is often misunderstood and misused. It is defined as the largest measurable signal divided by the minimum detectable signal. For digital photography the minimum detectable signal is set by the noise level. Increasing the bit depth reduces the quantization error, but does not, by itself, increase the dynamic range. Decreasing the noise level does.

There are lots of ways of affecting the signal to noise ratio in post processing. For example, downsampling an image trades spatial resolution for improvements in S/N. It decreases the noise by averaging over neighboring pixels. Similarly multiple exposure HDR improves S/N without losing spatial resolution by averaging over multiple pixels with different exposure settings. The drawback of course is that it only works for static images and therefore isn't too useful underwater.

Maybe in the future they can make multiple exposures fast enough that you could do HDR of moving subjects, but until that happens, the only way of improving the dynamic range its to make sensors that capture more light (deeper wells) and have lower readout noise. Even with the new canon it takes 100msec/frame. A lot can move in 100msec!

Steve

Your argument is with the producers of Photomatix - I qoute:

"Photomatix Increase the dynamic range of your photographs"

My point is that its pretty irrelevant if you are working in low contrast conditions (as I often do) where bit depth does become very relevant. But either way we are going to have to interpret files differently to how we do now.

I'm working on an idea to shoot bracketed shots underwater (ono-moving subjects) to see what can be achieved - I just neeed some vis.......

Steve

 

Your argument is with the producers of Photomatix - I qoute:

 

"Photomatix Increase the dynamic range of your photographs"

 

My point is that its pretty irrelevant if you are working in low contrast conditions (as I often do) where bit depth does become very relevant. But either way we are going to have to interpret files differently to how we do now.

 

I'm working on an idea to shoot bracketed shots underwater (ono-moving subjects) to see what can be achieved - I just neeed some vis.......

I think we are in violent agreement. Photomatix does increase the dynamic range of photographs when it is used with multiple exposures. When run with a single exposure, it does not. I also thing that increasing the bit depth is a good thing, so long as it is accompanied with an decrease in noise. Increasing bit depth can reduce banding, which is a good thing, but only if the noise is a few bit levels. If the noise is more than about 5 bit levels, increasing the bit depth doesn't do anything but make the files bigger.

I agree with you that multiple exposures of moving subjects could open up some interesting new ideas. For example, they could be used to create a pseudo-3D image. The things that move the most are either moving fastest, or are closer to the lens.

Multiple exposures could also be used as a backscatter reduction tool. The things the differ between multiple images are more likely to be dust and junk, than the subject.

Hi Steve

"Photomatix does increase the dynamic range of photographs when it is used with multiple exposures. When run with a single exposure, it does not."

If you re-read my posts I did not say it did - I said that it remaps tonality in a higher than 8-bit image, which as bit depth increases is something we are all going to have to get used to doing.

On an aside, I'd just like to put a point of view across about the detailed technicalities of digital photography. I am a photographer! It is an intensely practical undertaking. With digital photography it is easy enough to try something and learn from what you are doing (given the same basic knowledge of the parameters involved in taking an image - which have not substantially changed from film - although HDR IS an aspect which to a large extent has; I have shot multiple exposures, scanned and merged them in photoshop before but only on relatively simple subjects, actually sea-caves for a scientific survey). I read enormous amounts of highly detailed discussion on the merits/demerits of various aspects of digital technology on the web, but the real truth is that photography remains essentially about visualising and shooting an image. Increased specification of digital cameras is bringing new levels of 'quality' and technique, but in all honestly, being aware of them and their effect is only useful if it is applied to the 'real' world. I'm not having a go at anyone (certainly not Steve who hsa raised some interesting points) but I just feel it worth pointing out that I think that it is all too easy to get bound up in the theory and technology if you are not too careful. I've given up on several digital photographic web fora because of this.

All I was saying was that I was surprised that some pictures look better when taken on an old camera! Don't confuse me with technicalities!

All I was saying was that I was surprised that some pictures look better when taken on an old camera! Don't confuse me with technicalities!

All I was saying was that I was surprised that some pictures look better when taken on an old camera! Don't confuse me with technicalities!

You still own us some samples, at list for the ones from the correct side of the Atlantic

You still own us some samples, at list for the ones from the correct side of the Atlantic

By popular request...

By popular request...

What´s the buoy ancy and lift power of that vest?