Evening all, Been discussing some HDRI related work lately... and it got around to using it for "all light conditions" image recognition. That is, manipulating the tone/luminance of and HDR image in realtime so as to match the same tone/luminance as a stored image; making it easier to match images up... By my reckoning the software side of things isn't too much of a challenge. But I got thinking about the source data... Say we have 100 mugshots of people stored as HDRI files (The OpenEXR format for example) in a database. We then feed in a new image - one that was taken at night (into a half/single per channel buffer). The software measures and corrects the tone/luminance. All great. BUT, are there any digital cameras out there that generate true HDR images? Obviously, the incoming light (optical information) is as high definition as the hardware can capture - but at some point its going to be converted to a digital signal and stored in a digital format before being saved to whatever memory card the camera has. It's this "second" stage I'm interested in... If the lens captures everything at high definition, only to (at some point) drop it down to standard 8bit/channel RGB data then you've lost the dynamic range that you wanted. Even if it's later "re-converted" back to half/single precision HDRI data. These errors will obviously end up showing up somewhere further down the pipeline and somewhat negate the point of doing any of the process at anything higher than the lowest intermediary bit-depth. I just had a look around a few manufacturers websites checking out their high-end professional equipment and couldn't see any reference to models that could generate 48bit/96bit source information - although to counter that, it doesn't seem that they specify the models don't support it [smile]. Anyone come across any hardware that fits the bill? As an extension to this, do hardware CMOS/CCD components exist that capture the raw optical data at suitably high definitions? Cheers, Jack

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Cheers Yann. Looks like a damn nice toy... Chances of seeing it in real-life are probably also quite slim [smile].

I guess that camera can also do traditional point-and-shoot type camera images as well as 3D spherical images. But, does anyone know of any high-end SLR-type digital cameras. I'm thinking a high end camera that might well be used to capture a regular mugshot of someone - or something that can grab a CCTV style HDR image.

One possible angle on this idea is to try and match CCTV information against the national criminal database mugshots. I don't like the idea - I don't think it'll work very well, but I gotta at least give it some thought [smile].

Cheers,
Jack

Quote:Original post by jollyjeffers
Cheers Yann. Looks like a damn nice toy... Chances of seeing it in real-life are probably also quite slim [smile].

We'll going to use it for our next project, that's why I know about it. I have some test shots here, they're extremely impressive quality.

Quote:Original post by jollyjeffers
I guess that camera can also do traditional point-and-shoot type camera images as well as 3D spherical images. But, does anyone know of any high-end SLR-type digital cameras.

Not sure. Of course, the traditional principle is to use a set of increasing f-stops, capturing each at 8 or 10bits, and recombining the set to a HDR image. The result is the same as a direct full HDR capture, but it'll take some time, so realtime capturing is not possible.

The high end Canon EOS cameras can do 12 bit per channel RAW images. Not full 16 bit HDR but a step up from your standard 8 bit images. I imagine other high end digital SLRs have similar capabilities. I think it's pretty difficult to make a CCD that can cope with the full dynamic range of an Open EXR image with a single exposure / aperture setting. I remember reading about some CCDs that have multiple elements per pixel, each set to capture a different brightness range, which allows for greater dynamic range from a single shot.

I believe the physics of CCDs make it difficult to have a single element that can cope with the full extremes of dynamic range possible in real world scenes. It might be interesting if any given shot only captured a subset of the full dynamic range of an HDR image but stored the result in linear light space with some absolute scale. That would make it easier to compare images from different cameras with different exposure settings. You'd still probably get saturation in some areas however - if you had the sun in frame for example.

Quote:We'll going to use it for our next project, that's why I know about it. I have some test shots here, they're extremely impressive quality.

My project is for the university - I scored a 2 grand desktop for dedicated project use, but I think thats about as much as I can get away with.

The head of the school might hurt me if I asked for anything as expensive as that camera.

Quote:the traditional principle is to use a set of increasing f-stops, capturing each at 8 or 10bits, and recombining the set to a HDR image.

I hadn't connected this - but now you mention it, there is some research done within the school along these lines. Automating a way of generating HDRI data from a conventional camera using different exposures. Will give it a closer look when I get some time.

Quote:The high end Canon EOS cameras can do 12 bit per channel RAW images.

I'd imagine that 12bit/channel combined with what YannL was talking about would work quite nicely.

Quote:You'd still probably get saturation in some areas however - if you had the sun in frame for example.

Doesn't surprise me there is no "perfect" solution. However, a compiled image with a few artifacts is nothing new in the image processing field [wink], I suppose the questions would be either how bad the artifacts are, and what can be done to reduce/eliminate them.

Thanks for the information - been most useful.
Jack

To complete what mattnewport said, I'd like to add that all the digital reflex camera I know are able to store the HDR raw image. For example Nikon has defined the NEF image format which is used to store up to 12-bit per color images (yes, 12 bits per color is still HDR).

Now, capturing 16 bit of usable data per color is really hard to do. CCD and CMOS sensors that may be able to do this are very expensive. Most high-end CCD are only able to get 14 bits per color - that's good enough for most professionnal usage.

Now, you may find CCD sensors that may be better. They are used in academic astronomy devices. They are rare and - believe me - you don't want to buy one. You can find more informations about professionnal sensors on Kodak web and on Sony's web (others company do professionnal CCDs: atmel, Fuji, and so on)

Regards,

These things look pretty interesting - 22 Megapixels and a 16 bit uncompressed HDR image. How many bits of 'real' dynamic range they're getting out of the CCD I don't know but they still look pretty nice bits of kit [smile].

Thanks for all the links people [smile]. Bottom line conclusion is that the technology doesn't really exist to the same level that a real-time application might be able to handle unless you're willing to pay a small fortune.

Which, another topic I suppose, begs the question - how much advantage would "true" HDRI in realtime bring to standard images imported from digital cameras...

I'll give that one some thought and see what happens.
Cheers,
Jack