Absolutely.
Uniformity, rational uniformity...
May 18, 2023
439
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Ok no problem but given I don't know what data you have, and I don't need to know, then I take your comment
as your opinion and not an established fact, especially since I subsequently posted
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For ten years I used a Betterlight Super 6K. It had a raw histogram, but it wasn’t in camera, since that back needed a computer attached.
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Anyway, it looks like there is no widely known reason that I have missed seeing anywhere explaining why camera manufacturers do not offer in-camera histograms.
I'll just put it down as another one of life's mysteries.
Hopefully one day it will happen, but maybe not in my life time.
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Maybe they are lazy, maybe they did marketing research asking their customers: Do you want your camera showing Raw histogram or the normal RGB histogram?
And people who did not know what Raw histogram is and what it could do in camera answered. -
As far as I understand, internal data pipeline is largely the same, layout of pixel data in buffers and buffers themselves as they can be bound to certain addresses in memory. That includes the feed for LCD screen. Output file formats are obviously the same (although ML adds video modes AFAIR).
My understanding is, ML doesn't rewrite everything from scratch, it allows a developer to inject new functionality. It relies on Canon's firmware running along.
wiki.magiclantern.fm/faq -
I think the reason in-camera histograms are output-referred is that's what you're looking at in the EVF, nothing more than that. Histograms in the viewfinder are a pretty recent thing, and the firmware developers don't want to introduce a "WTF" indicator without establishing some sort of readily apparent frame of reference for it.
Thinking aloud, I think I'd prefer raw-anchored blinkies. With that, I could know measurements were being saturated AND where they are in the scene. That would be a tool that would be more readily useful in real-time...
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I think different cameras have different pipelines. The image processors have proprietary HW pipelines which will vary by vendor and model. The SW is likely to be very differently structured between different vendors, less likely between models because they'll likely be using the same code base - though sometimes they go through major changes due to HW revisions or changes to the RTOS.
But think about the process. The sensor can be programmed to work in a number of modes. Most likely while the VF is running it will be in a line-skipping mode at less that full ADC width, simply to get the frame rates. It will dump that output somewhere into a buffer which will likely get fed via DMA to a HW video processing pipeline, which is probably configured to give a feed for a VF / HDMI output somewhere. So, now the question is, if you want a raw histogram, where do you take the data. The VF feed is in processed space, so you really need to take it from the buffer, but that is just a DMA staging post, so likely needs a bit of reconfiguration to provide data for a raw histogram. It's clearly not impossible, but very likely the SW isn't structured to make it easy. The sensor doesn't get switched into full res/ full bit depth mode until it does an actual stills capture - so that data isn't available until then. -
I guess the data for a raw histogram is there right during applying WB and in-camera filters when feeding the buffers for LCD/EVF. As it converts raw to RGB, it can fill the histogram bins in because it goes through the raw pixels anyway. This stage should be present in any pipeline. If it's 12-bit readout instead of 14-bit and not all the pixels, I think it's still fine. I suspect there can be some minor performance hit compared to an RGB histogram though.
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I would be willing to pay a nominal fee to unlock raw histograms in firmware, similar to how I paid to upgrade my GH5's video capabilities. Indeed, I can think of a little basket of quality-of-life improvements that could be bundled into a "premium" firmware package that I'd pay for- the ability to select any arbitrary shutter speed instead of just "bulb", an intervalometer, greater flexibility in exposure bracketing, the ability to assign any function to any button, etc.
So, would I switch camera systems to get a raw histogram? No, there are too many other, higher priority considerations. But, would I be willing to pay a modest fee for a quality of life improvement? Yes.
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I'd be happy with either raw histogram or raw blinkies. Or both.
I didn't know it costs $50000 though. :( It would be cheaper to have a small laptop attached to the camera in the field and hire an assistant to carry all the gear. -
I would definitely use that if it was available.
Another thing I would be happy to try if it existed would be an ETTR mode for autoexposure. It would need to mask out hot pixels from the analysis.
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I think in most modern image processors that's all done in a dedicated HW pipeline. They're there to process video fast enough and will naturally be used for the VF. The only place to get at the raw data is in the buffer before it's fed to the pipeline. Not impossible to get at it there, but probably means some changes in basic SW structures.
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I would probably only learn that I had underexposed yet again because I don't have a Raw histogram in my camera. Ken
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Perhaps mfgs fear that raw histos would lead to bad images by the average punter. Faced with this ...
yes, it's log-log
... many would go "eek the blue is badly blown - must seriously reduce exposure" and end up with an image way too dark, followed by whine, whine, whine and the camera returned quickly to the store.
On the other hand, an average punter would likely produce this with the "normal" histogram and be delighted
Embedded JPEG from the same raw as above:
To certain members: please excuse the inclusion of a graph and mention of logarithms.: feel free to comment of course, but don't expect a response from me ...
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A couple of recent cameras fart around it. My Z 6 has a "highlight-weighted matrix" mode, which anchors the exposure to some part of the high end rather than middle gray; it typically leaves about a stop of headroom versus a true ETTR exposure. I use it as my default exposure mode, sometimes switching back to plain 'ole matrix for scenes where there's not too much dynamic range. I'd rather have raw blinkies...
Some recent Fuji cameras have something similiar; I'm not qualified to comment on it.
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I've never gotten consistent results with that mode. I gave up on it.
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Yeah, there's a reason camera meters anchor exposure to middle gray - consistency for what the photographer considers important. With a session of highlight-weighted exposures, I just count on spending time with the tone curves in post - I've arranged my hack software so I can do one of a sequence of the same scene then batch-apply the tone treatment to the others.
Recently, I find myself switching out of it more to do restoration documentation. A lot of the interesting bits are dimly lit backlighted by the sunlit tent in which the article sits, so I just meter on the subject and let the rest go to Hades...
