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normie100 Nov 3, 2014 6:04 PM

HDR camera

I own an SL1 that I believe is not going to be useful for the following, so I'm looking for something else for work that will.

I need a camera with high-dynamic range (meaning wide color points) and better-than-average quantization (at least 10bpc, preferably 12-16). Ultimately, I want to take actual photographs of the real world with fully-saturated color that I can map to the BT.2020 colorspace, for evaluating UHD TVs.

I have CS3, so I should be able to do some conversions if there are cameras that only output RAW providing all of the data. however, the custom device that will be used to drive the TVs, while using HDMI 2.0, will need custom SW to output whatever format the processing outputs--which should be okay (maybe even trivial), but I need to maintain the integrity of the image.

Any suggestions?

TCav Nov 4, 2014 8:08 AM

Start from scratch, creating a new image in CS3.

That is, don't bother with a camera; go straight to what you want.

normie100 Nov 4, 2014 4:56 PM

That kind of defeats the purpose of displaying real-world images. I can create test patterns, such as [SMPTE] Matrix patterns, and I can do this (or have this done) on the target platform in code. but test patterns may be a little difficult for subjects to determine the degradation that occurs from BT.2020 to BT.709. Theoretically.

The SL1 appears to be inadequate. I am leaning now to using a camera that will provide HDR using AEB and can output a RAW format that Photoshop can convert to something near the target. Currently reading the Adobe documentation to see what is possible.

But it is intriguing about making something non-real (unfortunately, I am not artistic) in Photoshop with the gamut we need...

TCav Nov 4, 2014 7:31 PM

Stick with Photoshop's .PSD files or TIFF files. You won't get the gamut you want with anything else.

RAW files don't have RGB values for each pixel. They have a luminance value that corresponds to the color of the Bayer Filter for the corresponding photoreceptor. Whatever color depth you can get from a RAW file will be diluted somewhat when R, G, and B values are interpolated for the neighboring pixels.

So don't start off by limiting yourself to 10 or 12 bit color (the limits of BT.2020.) Wait until you've got everything else you want before you start throwing away data.

BTW, there are no conventional still image cameras that can record 8K (7680 4320) images so your best bet might be to just work with video frames from an 8K clip.

TCav Nov 5, 2014 8:47 AM

BTW, HDR isn't generally something that comes straight out of a camera; it's something that you generally create in post processing from multiple images of the same scene captured at a variety of exposure settings. HDR images straight from the camera are generally obtained by the camera varying the ISO setting for each exposure, which has the unintended consequence of increasing the image noise in areas of the image that were darker in other images.

VTphotog Nov 7, 2014 2:06 PM

RAW files from the camera are usually 12 or 14 bit, so if you process with a 16 bit format, you should be OK for that aspect.
Bit depth, though, is not the same as color gamut. Developing the RAW files in a color space such as sRGB, even at 16 bits, won't give you any more color range than with 8 bits, just finer gradations. Your RAW converter would have to support the color space you want to use, or one with a similar color gamut. I think ProPhoto color space comes close. Does your Adobe Camera Raw converter have the option for the BT.2020 color space? If so, you should be able to process RAW files for what you want with it.

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