Author Topic: HDR image through Lightroom  (Read 1625 times)

2020-02-09, 13:05:21

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Hello dear Corona people!

Some time ago I have started post-proccesing my images with Lightroom.
I like to approach my images as real photographs thus Lightroom is a great tool.

Currently I am working on some interiors and I face a problem of overexposed (burnt) areas where the sunligh hits.
I have tried to solve the problem with "Highlight compress" and "Filmic highlights" but in order to eliminate the burnt areas I have reached values where the result is not appealing (flat and fake-ish light).

In photography, there is a technique where you take multiple exposures of the same scene and then you merge all of them in Lightroom in order to create an HDR image, where highlight are not burnt and shadows are not crushed black. It's called "bracketing"

I have tried to replicate this technique with my renders but Lightroom seems to not accept 16bit or 32bit tiff images for HDR merge.

I was wondering if there is someone out there who knows if that works and if it works, what's the process for it.

Cheers,
Christos
We offer Visual Communication

2020-02-09, 13:49:31
Reply #1

romullus

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Hi,
The process is very simple - save your render as exr and you alreaddy will have HDR image, no need to merge anything. Now, wether you can work with 32bit linear images in Lightroom, i don't know answer to that.
I'm not Corona Team member. Everything i say, is my personal opinion only.
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2020-02-09, 14:29:49
Reply #2

Image Complete

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Hi,
The process is very simple - save your render as exr and you alreaddy will have HDR image, no need to merge anything. Now, wether you can work with 32bit linear images in Lightroom, i don't know answer to that.

Hello!
Unfortunately Lightroom does not accept exr files. It is strange because it is made to accept raw files from photography, but it happens.
However, even if Lightroom could read exr files, it seems that the limits of a signle exr file are not enough for the occasion. As I mentioned, I cannot fix the problem inside VFB. As far as I know, the image on the VFB is 32bit so the results inside Lightroom would be no different.
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2020-02-09, 14:44:51
Reply #3

pokoy

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I'm not sure Lightroom can process bracketed shots. But in PS you can get local compression when converting 32 to 16 bpc. Also, there's a command called Photomerge or something which produces HDR photography from bracketed shots. For that it needs the images to be saved with different exposure, -3 EV, -2, -1 etc, you load them and specify exposure times and it produces some output which may or not be satisfactory though...

2020-02-09, 14:54:36
Reply #4

Image Complete

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I'm not sure Lightroom can process bracketed shots. But in PS you can get local compression when converting 32 to 16 bpc. Also, there's a command called Photomerge or something which produces HDR photography from bracketed shots. For that it needs the images to be saved with different exposure, -3 EV, -2, -1 etc, you load them and specify exposure times and it produces some output which may or not be satisfactory though...

Lightroom can process bracketed shots. The command of Photomerge you talk about can be done in Lightroom too with 2-3 clicks. This is what I was trying to do but it fails with tiffs (16 or 32bit)

I will try with Photoshop to see what happens.

Thanks
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2020-02-09, 15:12:08
Reply #5

romullus

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Hello!
Unfortunately Lightroom does not accept exr files. It is strange because it is made to accept raw files from photography, but it happens.
However, even if Lightroom could read exr files, it seems that the limits of a signle exr file are not enough for the occasion. As I mentioned, I cannot fix the problem inside VFB. As far as I know, the image on the VFB is 32bit so the results inside Lightroom would be no different.

32bit/16bit EXRs has much wider dynamic range than RAW photos, so everything you can do with RAW, you can definitely do with EXR too. Maybe you need to look for better software, that is able to handle EXRs? On the other hand, it might be worth to try to tweak the image as best as you can right in the VFB (use highlights compression if you need too), then save it to 16bit TIFFs and finish it in Lightroom.
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2020-02-09, 15:27:56
Reply #6

Juraj

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32bit/16bit EXRs has much wider dynamic range than RAW

Indeed, it's this. Quite often people assume that HDR from bracketed photos are somehow different than HDR straight out of framebuffer. It's because:

-Many people bracket jpegs or tiffs that already have camera curve applied in HDR photomerging, so the resulting HDR (before tonemapping algorithm gets applied) already looks richer and crispier.
-HDR Softwares offer local-tonemapping instead of global tonemapping (or both). Imho Local-Tonemapping is the ugly shit from 2000 that I am happy has died, it looks terrible even in moderation.
-Highlight compression in any raw editor is still much superior to Reinhard (or the broken filmic) in Corona. It's nice curve that doesn't flatten midtones to mushy ugliness.

To get around the limitations that common raw editors and HDR editors have in regards to importing linear 32bit files...the "get-around" of manually re-saving HDR from framebuffer into individual brackets is as old as CG-Architect forum itself :- ).
I have seen this advice 10 years ago...

It's absolutely stupidity, but if you want to do it, you also need to modify exif of those files or have HDR editor that enables you to manually specify the EVs of your "fake" brackets.

The outdated and forgotten PS plugin ArionFX enables you to do all of this directly. It has every single global and local tonemapper...except for filmic.

The best approach currently used by interior photographers is to use minimal highlight compression, zero HDR, and do lot of manual tweaks (gradient exposure, compositing exposures with masks,etc..).
This gives natural look. To simulate this from Corona, never use more than 2 in HL. Yes it's bright..you need to the the rest in smart ways, just like photographers. It's identical.

So-called "HDR" (drastic local tonemapping) was never good looking.
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2020-02-09, 17:03:04
Reply #7

Image Complete

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32bit/16bit EXRs has much wider dynamic range than RAW

Indeed, it's this. Quite often people assume that HDR from bracketed photos are somehow different than HDR straight out of framebuffer. It's because:

-Many people bracket jpegs or tiffs that already have camera curve applied in HDR photomerging, so the resulting HDR (before tonemapping algorithm gets applied) already looks richer and crispier.
-HDR Softwares offer local-tonemapping instead of global tonemapping (or both). Imho Local-Tonemapping is the ugly shit from 2000 that I am happy has died, it looks terrible even in moderation.
-Highlight compression in any raw editor is still much superior to Reinhard (or the broken filmic) in Corona. It's nice curve that doesn't flatten midtones to mushy ugliness.

To get around the limitations that common raw editors and HDR editors have in regards to importing linear 32bit files...the "get-around" of manually re-saving HDR from framebuffer into individual brackets is as old as CG-Architect forum itself :- ).
I have seen this advice 10 years ago...

It's absolutely stupidity, but if you want to do it, you also need to modify exif of those files or have HDR editor that enables you to manually specify the EVs of your "fake" brackets.

The outdated and forgotten PS plugin ArionFX enables you to do all of this directly. It has every single global and local tonemapper...except for filmic.

The best approach currently used by interior photographers is to use minimal highlight compression, zero HDR, and do lot of manual tweaks (gradient exposure, compositing exposures with masks,etc..).
This gives natural look. To simulate this from Corona, never use more than 2 in HL. Yes it's bright..you need to the the rest in smart ways, just like photographers. It's identical.

So-called "HDR" (drastic local tonemapping) was never good looking.

Although the Photomerge in Ps works (because it asks for EV values, so there is the point which you fake the EVs), your suggested approach creates much better results indeed. My image, although not burnt, was flat on midtones and mushy! I knew something was wrong but I couldn't identify it. Sometimes you have to follow the basics I guess!

Cheers!
Christos
We offer Visual Communication

2020-02-10, 07:46:51
Reply #8

Njen

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FYI, Darktable is the open source equivalent to Lightroom, and it can read exr's. No need to screw around Lightroom's limitations with file formats and Adobe's predatory tactics in general.

2020-02-11, 10:20:24
Reply #9

Juraj

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FYI, Darktable is the open source equivalent to Lightroom, and it can read exr's. No need to screw around Lightroom's limitations with file formats and Adobe's predatory tactics in general.

Huh, never even heard of, but looks like another alternative to Adobe which is good.

I am CapturePro user...and they don't care about .exrs either.
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