Known Participant

Question

Can't seem to get 30 bit view

Forum|Forum|4 years ago
July 2, 2021
4 replies
2972 views

I recently got an HDR monitor with 10 bit colordepth (so 30 bits in total). I have it running in windows, and HDR videos works fine. I don't normally use photoshop, instead I use lightroom, but I'd already heard that there's so far no hope for 10bit colors there, so I installed photoshop as well, and found the option for 30bit color depth. I can click it, and set it, it's not greyed out or anything. I import a raw file, set its color depth to 16 per channel, wide-gamut rgb profile.. and nothing seems different than when it was still in normal mode.

I even boosted the exposure of the photo to blow out the sky, and in an adjacent window had some HDR video open, which was way brighter than the blown out sky, aka, photoshop's not outputting 10 bit data to my monitor. Why not?

It's a bit impossible to take a screenshot showing the difference in brightness, as HDR screenshots aren't really a thing. So, this crappy photo will have to do. It should be quite clear that the white in the video is a lot brighter than the blown-out sky in my photo.

Does anyone know how to fix this? Alternatively, is there maybe some way I don't know of in Lightroom to do it? That's my 'endgoal', honestly, I'm surprised that it doesn't have it already, or that this is so troublesome.

This topic has been closed for replies.

M

maxm54353747Author

Known Participant

So despite everyone here claiming that I fundamentally misunderstand HDR and that what I want is impossible; they've actually implemented exactly what I wanted recently, and now you CAN view photos in HDR.
So... yeah...

There is a new issue, though 😧 Exporting the HDR files, they don't appear, well. 'right' in anything other than Lightroom.
Chrome comes close if I export to hdr AVIF although still darker than it should be. Opening it every other program I've tried makes it look grey and washed out.
Anyone any clue?
I should probably make a new issue for this.

davescm

Community Expert

Have you also set 10 bit in the GPU driver? This is the relevant setting in the current NVidia driver for their RTX cards:

Dave

Trevor.Dennis

Community Expert

An interesting thread. I didn't know about the GPU driver requirement.

D Fosse

Community Expert

I think you misunderstand what 30 bit depth is. It has nothing to do with dynamic range and you're not supposed to see any immediate difference.

30 bit depth is the number of discrete values between black and white - 1024 vs 256. The net effect is that you don't see banding in smooth gradients. That's all.

To put it another way - the ladder is the same length, but the distance between each step is shorter.

BTW, you have to enable this in the video driver as well as in Photoshop.

M

maxm54353747Author

Known Participant

I understand, but it may be due to Window's and Adobe's different ideas on how to implement this.
For 8 bit, #000000 would be black, and the lowest light the monitor can give off, ideally 0 cd/m2 (candela per square meter), but backlight will shine through in all but oled screens.

For 8 bit, #ffffff would be white, like the text box I'm typing this in now. For a standard monitor, that would be about 350 cd/m2.
However, in HDR mode, the monitor has 10bits per color, meaning it can go up to #hhhhhh, though I don't think it's ever written that way. However, an HDR monitor must also be significantly brighter, for example, my new monitor goes to 600 cd/m2. Since a lot of UI ellements on the screen are white, you'd be blasted with full brightness all the time, which is unpleasant, or downright painful if you have a very high end monitor that goes up to like 2000cd/m2. Window's HDR implementation 'fixes' this by basically mapping standard SDR content onto the lower parts of the brightnes values, ideally bascially onto the first 8 of the 10 bits per color channel, though I doubt it's that straight forward. Meaning that even though the window background is white, once and HDR video/game/whatever plays where it even in 10bits depth it's white, it's way brighter than the other white, which by comparison looks grey. (like how paper laid out on the ground on a cloudy day looks white, until you lay down a mirror next to it (which reflects the overcast sky)).
Windows provides a brightness slider to affect how bright SDR content will look, if you turn it up to the max, light grey and white look the same, you lose the black levels, so that's no good to edit photos in. But if I don't set it to the max, my whites in the photos in Photoshop won't reach the full brightness of my monitor, meaning it's not utilizing my monitor's full dynamic range, aka not HIGH dynamic range. Actual HDR content is unaffected by the slider, Photoshop, regardless of its 30bit option, is affected.
I am hoping for a method of having Photoshop, or even better Lightroom mimic the behaviour of the HDR videos and games. Is that possible?

davescm

Community Expert

You say the white in 10 bits should be the same as in 8 bits, yet my photo in the post shows that it is not. As white as photoshop will go, as not as white as my monitor will go, the white in the video in that photo is brighter.
I've never used photoshop before, but I've worked with Lighroom for many years. I've made countless of 'HDR' photos, where I take 3 or more photos of different exposures, and combine them into one 16bit image, which I then tonemap onto an 8bit image.
I don't want to optimize my photos for prints, I want to optimize them for an HDR monitor. But I can't VIEW them in HDR, even if photoshop says it's in 10 bit mode, it refuses to actually use the full brightness dynamic range, even though it has the bits for it. Just using a 16 bit, or even 32 bit file is old news, the latter I've done plenty in astrophotography too. You can process it like that, but the last step is always tonemapping it one way or another back to same old 8 bits. I don't want that. I want to tonemap it to 10bits, and have it display those 10 bits 1:1 on my screen, the black being as black as my screen goes, the white as bright as it goes. I don't understand why this is seemingly such an impossible request? Why else would HDR screens exist? To not use their brightness? Setting it down to 100cd/m2? I want the sun in my photos to pop at my screen's full 600cd/m2, whilst still seeing the details in the shadows, which IS possible, I've seen it, on my very own screen, in HDR sample videos. Why can't I replicate that? If not photoshop, what other kind of magical software do I need for this?

"You say the white in 10 bits should be the same as in 8 bits, yet my photo in the post shows that it is not"

Your photo in the post shows nothing at all. It compares an image in a browser from a video (which does not use ICC colour management) to a Photoshop screen which is colour managed.

"the last step is always tonemapping it one way or another back to same old 8 bits."

Wrong. You can tonemap to 16 bits which is more steps than any current display can show.

"even if photoshop says it's in 10 bit mode, it refuses to actually use the full brightness dynamic range"

You are still hanging on to the incorrect view that bit depth and extended dynamic range are the same thing. They are not. All bit depth does is divide the dynamic range of your colour space into more, or less, steps.

With that out of the way, if you want to set your monitor to maximum brightness then do so. Use a calibrator and make sure that you produce a profile that describes your monitor in that space. Then set the working space for your document to an HDR space and adjust and tonemap your image accordingly. Your image though will be adjusted to look good on your system and is unlikely to look good on others.

If you adjust images to send onwards for others to view, you would need to switch your calibration to a more "normal" brightness and also switch the profile to match that. That is made much easier on a professional monitor, such as an Eizo, with internal calibration and auto switching of profiles.

Dave

Trevor.Dennis

Community Expert

This person might know. @D Fosse He'll be tagged about this thread.

Sign up

To post, reply, or follow discussions, please sign in with your Adobe ID.

Sign in to Adobe Community

To post, reply, or follow discussions, please sign in with your Adobe ID.

Scanning file for viruses.

This file cannot be downloaded