HDR Workflow with PTGui and Photoshop CC/LR5

[Guido Brandt]

Hi all,

I am newbie of this group, but have been doing some simple landscape panoramas with PTGui for a while now.   One problem that often comes up in these landscape images is dynamic range within these panoramas.

I had a look at previous post regarding a HDR workflows for panoramas, but couldn't really find the answers that I was looking for.  I am basically asking for your experiences of getting the most out of the base RAW images.
Also LR5 or PS CC have recently introduced nice solutions to work with 32-floating bit images that in my opinion seem to be more intuitive and give more natural results than buying and learning a tone mapping program like Photomatix.

With regards to my questions I am assuming that I have captured the panorama using a tripod and used bracketed exposures of e.g. 0, -1, 1  or 0,-2,-1,1,2  in manual mode and RAW files.

So here are some of my thoughts and questions:

1.  I assume the only advantage of capturing the base files in RAW cvs JPG is the flexibility with WB, chromatic aberration, better NR recovery and lens correction. The RAW file shouldn't give me an advantage regarding dynamic range.  Do you agree?

Therefore I can think of the following workflow variances:

Panorama 16-bit input, 32-bit output  version 1:

1. Process multi-bracketed images with Adobe Camera Raw or LR (common WB, noise reduction and basic sharpening, lens corrections, leaving all other parameters untouched) and export each exposure as a 16-bit TIFF
2. Open  TIFF's into PTGui and generate HDR panorama (using the Enfuse Plugin), exporting one 32-bit floating point file as EXR, TIFF or HDR in a
3. Open  32-bit file into PS, create a smart object and use the Camera Raw Filter to process and convert into a 16-bit file.

Panorama 16-bit input, 32-bit output  version 2:

1. Process multi-bracketed images with Adobe Camera Raw or LR (common WB, noise reduction and basic sharpening, lens corrections, but also adjust highlights, shadows, whites and blacks individually for each image) and export each exposure as a 16-bit TIFF
2. Open  TIFF's into PTGui and generate HDR panorama (using the Enfuse Plugin), exporting one 32-bit floating point file as EXR, TIFF or HDR in a single layer.
3. Open  32-bit file into PS, create a smart object and use the Camera Raw Filter to process and convert into a 16-bit file.

Panorama 32-bit input, 32-bit output  version 1:

1. Process multi-bracketed images with Adobe Camera Raw (common WB, noise reduction and basic sharpening, lens corrections) and merge the bracketed files into a 32-bit file using PS HDR Pro. Alternatively you could use the Merge-to-32 Plugin for LR.
2. Open  32-bit TIFF's into PTGui and generate HDR panorama, exporting again as 32-bit floating point file in a single layer.
3. Open  32-bit file into PS, create a smart object and use the Camera Raw Filter to process and convert into a 16-bit file.

Panorama 32-bit input, 32-bit output  version 2:

1. Process multi-bracketed images with Adobe Camera Raw or LR (common WB, noise reduction and basic sharpening, lens corrections, but also adjust highlights, shadows, whites and blacks individually for each image) and merge the bracketed files into a 32-bit file using PS HDR Pro. Alternatively you could use the Merge-to-32 Plugin for LR.
2. Open  32-bit TIFF's into PTGui and generate HDR panorama, exporting again as 32-bit floating point file in a single layer.
3. Open  32-bit file into PS, create a smart object and use the Camera Raw Filter to process and convert into a 16-bit file.

Would love to hear what you all think of this or if you had experiences with it?

Guido

[PTGui Support]

Hi Guido,

On 16/07/14 09:28, Guido Brandt wrote:
> 1. I assume the only advantage of capturing the base files in RAW cvs
> JPG is the flexibility with WB, chromatic aberration, better NR recovery

Indeed.

> and lens correction. The RAW file shouldn't give me an advantage
> regarding dynamic range. Do you agree?

RAW files do give you more dynamic range than JPG files: 12-14 bits vs 8
for jpeg. But this is only a concern if you do not shoot bracketed. If
you create HDR from bracketed images you're already extending the
dynamic range.

You shouldn't do any barrel distortion correction before stitching,
PTGui can do this better.

> Therefore I can think of the following workflow variances:
>
> Panorama 16-bit input, 32-bit output version 1:
>

> 1. Process multi-bracketed images with Adobe Camera Raw or LR (common

> WB, noise reduction and basic sharpening, lens corrections, leaving
> all other parameters untouched) and export each exposure as a 16-bit
> TIFF

> 2. Open TIFF's into PTGui and generate HDR panorama (using the Enfuse

> Plugin), exporting one 32-bit floating point file as EXR, TIFF or
> HDR in a

Expsore fusion (PTGui doesn't use enfuse but it has the same algorithm
built in) already creates a 8 or 16 bit low dynamic range image.
Basically it combines the steps of HDR generation and tone mapping into
1 process.

If you use the True HDR workflow in PTGui you'll get a 32 bit image,
which can be tone mapped either in PTGui or in an external application
to get a low dynamic range image.

Please see the HDR tutorial:
http://www.ptgui.com/hdrtutorial.html

> 3. Open 32-bit file into PS, create a smart object and use the Camera

> Raw Filter to process and convert into a 16-bit file.

No, raw development and tone mapping are two different things.

> Panorama 16-bit input, 32-bit output version 2:
>

> 1. Process multi-bracketed images with Adobe Camera Raw or LR (common
> WB, noise reduction and basic sharpening, lens corrections,*but also

> adjust highlights, shadows, whites and blacks individually for each

> image*) and export each exposure as a 16-bit TIFF

I would only do WB and noise correction here. Use the same settings for
all your images. Sharpening should be done as a final step. Adjusting
exposure before merging the bracketed images confuses the algoritms in
PTGui (which expect straight-from-camera images) but does not
necessarily give a bad result.

> Panorama 32-bit input, 32-bit output version 1:
>

> 1. Process multi-bracketed images with Adobe Camera Raw (common WB,

> noise reduction and basic sharpening, lens corrections) and merge
> the bracketed files into a 32-bit file using PS HDR Pro.
> Alternatively you could use the Merge-to-32 Plugin for LR.

> 2. Open 32-bit TIFF's into PTGui and generate HDR panorama, exporting

> again as 32-bit floating point file in a single layer.

> 3. Open 32-bit file into PS, create a smart object and use the Camera

> Raw Filter to process and convert into a 16-bit file.

This would work to (but again the final step should be tone mapping, not
camera raw).

> Panorama 32-bit input, 32-bit output version 2:
>

> 1. Process multi-bracketed images with Adobe Camera Raw or LR (common
> WB, noise reduction and basic sharpening, lens corrections,*but also

> adjust highlights, shadows, whites and blacks individually for each

> image*) and merge the bracketed files into a 32-bit file using PS

> HDR Pro. Alternatively you could use the Merge-to-32 Plugin for LR.

> 2. Open 32-bit TIFF's into PTGui and generate HDR panorama, exporting

> again as 32-bit floating point file in a single layer.

> 3. Open 32-bit file into PS, create a smart object and use the Camera

> Raw Filter to process and convert into a 16-bit file.

Again I'd limit step 1 to only WB and noise reduction.

Joost

[Erik Krause]

Am 16.07.2014 10:17, schrieb PTGui Support:
>> > 3. Open 32-bit file into PS, create a smart object and use the Camera
>> > Raw Filter to process and convert into a 16-bit file.
> No, raw development and tone mapping are two different things.

Joost, the latest versions of ACR / Lightroom can open 32bit floating
point images and do a really good tone mapping. See f.e.
http://www.adobepress.com/articles/article.asp?p=2117241

My only concerns would be that they don't care about the 360° seam,
zenith and nadir. But the results are really good - much better than
anything you can get with photomatix (at least at default settings).

You don't need photoshop CC to do this. CS6 ACR (8.3) can open 32bit
TIFFs (and 32bit DNGs) as well, but you need to open them from Bridge.

--
Erik Krause
http://www.erik-krause.de

[Roger Williams]

Erik,

Thank you for that link. As you know, I am not very proficient in using
Photoshop, but this article makes me determined to make better use of ACR
and CC to tone-map HDR files. I am quite happy with the tone mapping that
SNS-HDR does, but keeping it all within ACR/CC (where I do my CA elimination
anyway) has the possibility of simplifying my workflow. As I am now moving
towards multiple exposure stereo panoramas (20 or 30 exposures each with
three-exposure bracketing) the old workflow is already unviable.

Roger W.

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[DennisS]

"The RAW file shouldn't give me an advantage regarding dynamic range.  Do you agree?"

Words do not describe how much I disagree with this statement.

 

A .jpg file has a vast majority of the information stripped away.  That is why the file size is so much smaller.  RAW maintains all the images as the sensor captured the image.  Basically an engineer working for the camera company decided how your RAW images should be processed "in camera" in order to produce a .jpg file.  If all you ever shoot are the same old boring pictures like our fearless leader known as"KR" does, .jpg is fine.  If you shoot something that people will actually be interested in looking at the dynamic range might be more than a .jpg can handle.

 

You can recover highlights and lighten shadows much more effectively if you shoot RAW vs .jpg.  People have commented on my good HDR technique when all I did was properly expose and shoot a single set of RAW images.  No bracketing or HDR.

 

The few times I have done HDR my workflow is this:  Use ACR to extract the individual bracketed .tif pictures from a single RAW image correcting for everything except saturation and sharpening.  HDR merge each individual view using Photomatix.  Stitch the individual views in PTGUI (do not let PTGui do the HDR portion).  Go back to Photoshop for final color corrections and sharpening.

 

Dennis

[PTGui Support]

On 16/07/14 21:25, Erik Krause wrote:
> Am 16.07.2014 10:17, schrieb PTGui Support:
>>>> 3. Open 32-bit file into PS, create a smart object and use the Camera
>>>> Raw Filter to process and convert into a 16-bit file.
>> No, raw development and tone mapping are two different things.
>
> Joost, the latest versions of ACR / Lightroom can open 32bit floating
> point images and do a really good tone mapping. See f.e.
> http://www.adobepress.com/articles/article.asp?p=2117241

I didn't know that. The tone mapping quality is very good indeed. But
they sure hid this feature very well in Photoshop..

Joost

[PTGui Support]

On 17/07/14 08:08, DennisS wrote:
> The few times I have done HDR my workflow is this: Use ACR to
> extract the individual bracketed .tif pictures from a single RAW image
> correcting for everything except saturation and sharpening. HDR merge
> each individual view using Photomatix. Stitch the individual views in
> PTGUI (do not let PTGui do the HDR portion). Go back to Photoshop for
> final color corrections and sharpening.

I think you can get the same results by converting your raw file to a
single 16 bit tiff; a camera sensor has just 12 to 14 bits of dynamic
range. Just be sure to convert the raw file such that highlights are not
clipped.

And PTGui 10 can tone map panoramas without using bracketed images, but
you can of course use another tone mapper if you prefer.

Joost

[Guido Brandt]

Dennis,

sorry - I should have been clearer on this.  I am certainly aware of the benefits of RAW capture in general.  My point/question though was more related to when capturing bracketed exposures in jpg vs RAW.
Here I don't see why raw should really provide an advantage because I am overcoming the limitation of the dynamic range of the jpg (8-bit vs. 12-14bit in RAW) by bracketing.   So the bracketing gives me more information already.

Like I said before the only advantage is the flexibility in WB, NR and lens correction.

Guido

[Jeff Wischkaemper]

Wow... this is a lively discussion. So many things to say.

Guido - As a scientist, I wish the world worked this way, but it doesn't. You don't automatically get a 24-bit image by stacking 3 8-bit ones, unfortunately. Let's think about it in terms of an 8-bit TIFF, since that is easier. Each color in the 8-bit TIFF file has 256 possible values, ranging from 0-255. If you take three, 8-bit bracketed shots, then your darkest shot will have relatively low values, including, probably, several zero or near zero values, but will have detail in the highlight areas, your "normal" shot will be properly exposed, with a wide range of values from 0-255, and your "bright" shot will be skewed with many values near 255, but have actual detail in the shadows. When you combine these shots, you are combining areas where detail is properly exposed - you are not actually expanding the range of the data. In other words, the resultant image will still have 8-bits of detail, even though you bracketed the shots.

Joost is correct, though, that the conversion from 12 or 14-bit raw to 16-bit TIFF should be more or less lossless , at least in terms of dynamic range. It's not quite correct to say that it's lossless full stop, since the RAW converter needs to de-Bayer the sensor data to get color, as well as do some other pre-processing of the data, and some converters (ACR) are better at this than others (DCRAW). 

Also, it's important to remember, for everyone, that a 12-bit image has 16x the information of an 8-bit image (each bit effectively doubles your number of quantization steps). 

With regard to TIFF vs. RAW vs. JPG for inputs, I would be more concerned about the uncertainty in how JPG compresses the areas of detail when combining files, more than the dynamic range issue. You can think of the JPG compression function as introducing a particular kind of noise into the image, which may be amplified the more shots you combine. Using RAW files is problematic due to the inline use of DCRAW, which is far from optimal. 

In general, I would recommend conversion to 16-bit TIFF, from RAW, with a competent RAW converter such as ACR, as "best practice." My personal feeling is that letting ACR handle WB conversions is the best way to go, since the conversion happens at the de-Bayering layer, not after color has already been assigned. 

Unfortunately, my experience with shooting HDR panoramas is that there is no "one size fits all" solution. In some cases, PTGui's EXR output gives me the best results. In others, exporting the individual layers to a PSB and merging with HDR Efex Pro is better. In other cases, I actually get a better tone map when using the exposure fusion algorithms in either PTGui or PTAssembler. 

Ultimately, you need to get the workflow that works for you. Processing with 16-bit TIFFs is time and space consuming, but I've found it to give the best results. I'm more than happy to share additional details of my workflow, if you're interested, but make sure that whatever you do works for you.

[Erik Krause]

Am 17.07.2014 11:45, schrieb Guido Brandt:
> Here I don't see why raw should really provide an advantage because I am
> overcoming the limitation of the dynamic range of the jpg (8-bit vs.
> 12-14bit in RAW) by bracketing. So the bracketing gives me more
> information already.

True so far, if you cover the complete dynamic range with jpeg brackets.
However, there is still a benefit using raw even if you shoot bracketed,
although not as much as from a single raw vs. single jpeg. Most cameras
do a -2, 0, +2 step bracketing only, effectively adding 4 stops of
dynamic range. Given a raw image covers 11 EV and a jpeg 8 EV, then you
get a total dynamic range of 15 EV for raw and 12 EV for jpeg brackets

A second advantage is you have some room for fake HDR. I shoot handheld
frequently (yes, even bracketed - a 5 brackets example here:
https://www.360cities.net/image/flying-over-eichelspitz-tower ), and
sometimes one exposure step won't align no matter what I do. In this
case I use a neighboring step and adjust exposure such that it fits the
other images in order to get the same tonemapping. Same applies for
moving objects, camera shake etc.