32-bit HDR Myths and Methods

32bit32 Bit  HDR Myths and Methods

A funny thing happened a couple years ago with the introduction of Lightroom 4.1. I started seeing people talking about NOW processing their HDRs in 32-bit. Now while it was true that something new happened – 32 Bit Tiff support for both Adobe Lightroom 4.1and ACR 7.1- many people seemed to think that 32-bit processing in any program was not possible before this and even the confusion that Lightroom and Photoshop ACR  (Adobe Camera RAW) were the ONLY programs that did work in 32-bit (Color Bit depth), which simply wasn’t true. All the Major HDR Programs do their processing in 32-bit, Photomatix Pro, Nik by Google HDR Efex Pro 2, Oloneo all of them work in 32 bit depth while in their Tonemapping/processing modules. Period

So, I kinda just left it alone, figured everyone would figure it out after the hype but then I found 2 years later after talking to people and watching a few HDR Workflow videos that people hadn’t figured it out and worse than that, really weren’t sure when they were working with a 32-Bit image.

I thought I would write this article to clear up a few things and also to give a few ways that you can work in 32-bit, How you can make a 32-bit file and the types supported and what is best to do while in 32-bit and when it’s time to call it quits and begin your final processing in other bit depths (16-bit, 8-bit)

Types of 32 bit files

There are 3 general types of 32-bit files or file types that you can save 32-bit in.

32 bit Floating Point Tiff. This is the most commonly used type and  the only type that Lightroom and ACR will work on, although Photoshop itself can open/save other types

Radiance RGBE32 bit (.hdr) Photomatix Pro,  and Photoshop (Not ACR) can open/save as this file type. HDR Efex Pro2  can Open this type (see later notes)

OpenEXR: Photomatix Pro  and Photoshop (Not ACR) can open/save as this file type

There are some technical differences in the 3 file types. The differences only come into play if you can use a file type or not so I won’t go into the differences here since it may all be moot but you can do a search if it interests you

32 Bit File Compatibility

Lightroom: 32 Bit Floating Point Tiff only

Photoshop ACR: In Native ACR mode: 32 Bit Floating Point Tiff only. You can only access the 32 Bit file by using Mini-Bridge (File>Browse in Mini-Bridge) and then right clicking the file and say “Open in Camera RAW”

Photoshop, 32 Bit Tiff, Radiance.hdr, Open Exr: Open/Save directly: In Photoshop CC only; you can access ACR by using the Filter> Camera RAW Filter

Photomatix Pro: 32 Bit Tiff, Radiance.hdr, Open Exr:  Open/Save directly. 

Nik by Google HDR Efex Pro 2: Post the Google take-over suite version; you cannot open a file launching HDR Efex Pro2. Versions prior to that if you didn’t update can open: 32 Bit Tiff, Radiance, Open Exr Directly. The workaround for this if you have Photoshop is to open any of the 3 file formats in Photoshop and then go to Filter> Nik> HDR Efex Pro 2. 

Creating a 32 bit file

If you are already using one of the major HDR Programs, you don’t really have to do anything; your normal workflow creates a 32 bit file with which to work on the tone-mapping processing. But you may want to work on the file in different programs while still in 32 bit and that isn’t always so easy since most programs output in either 16 or 8-bit, yes even Lightroom and Photoshop ACR will do this if you are not careful.

Photomatix: You can create a 32-bit file by using Photomatix as a stand alone. Open the program and click on the “Load Bracketed Photos” Navigate to your Files by hitting browse and select them and then the important step is to: Check the box for “Show 32-bit unprocessed image Photomatix LoadPhotomatix will go through the normal Merge process but then stop at a point when the 32-Bit image is established but before Tone-mapping. It is at this point that you will make your 32 Bit File in your choice of the above 3 and go up to and Save the File as a 32 Bit format Do NOT go on to Tonemapping In Photomatix.

If you have made any adjustments to your RAW Images in Lightroom or ACR, those changes will not be usable in this method as Photomatix does not read XMPs. So you must make Tiffs or Jpegs (16-bit Tiff preferred) with the LR Edit prior to the merge in this method

Photomatix Via Lightroom:Prior to Photomatix  Pro 5 this was also an Option on export from Lightroom. HDRSoft removed this option in Pro 5 but offered a new Method, their Merge to 32 Bit Lightroom Plug in. The advantage of this is you can do all your selecting of images in your Lightroom Library, Then add develop settings (White Balance, Len correction etc) and then Merge the file in Photomatix using it’s great merging and deghosting and then bring the Merged file back into Lightroom as a 32 Bit Floating Point Tiff but without any of Photomatix’s Tone Mapping.

Lightroom: You can not make a 32 Bit file directly in Lightroom alone. You much use either the Photomatix Methods above or the Photoshop Methods below

Photoshop: There are two main ways to make a 32 Bit file in using Photoshop.

From Lightroom: Select your exposures, right click and choose: Edit in: Merge to HDR Pro in Photoshop. When the Merge dialog comes up make sure that the dropdown in the upper right is set to 32 bit. When the Image is merged, click save and the image will come back to Lightroom as a Tiff where you can then Develop/Tone-Map/Edit the 32-BitMerge to HDR pro

From Bridge: Select your Exposures go up to Tools>Photoshop> Merge to HDR Pro. Again when the merge dialog comes up make sure it is set to 32 Bit. From here you can work on the file in Photoshop using the Limited 32bit tools and adjustments available. In Photoshop CC you have the option of going right to The Camera RAW Filter. Otherwise to use ACR, save the 32bit as a Tiff and then re-open the image in Mini-Bridge, right click and select Edit in Camera RAW. You also in Photoshop CC can make Camera RAW a Smart Filter by first clicking under the filter menu, Convert for Smart Filter and then clicking on Camera RAW Filter (in case it doesn’t make it a Smart Filter by default)

Nik by Google HDR Efex Pro 2/ Photoshop CS6 and earlier with this combination of programs you can also create a 32 Bit File. It doesn’t seem to work for me with Photoshop CC although it may be a Nik Installation problem with CC so your results may vary.

How you get to a 32 Bit file  is to have HDR Efex Pro 2 open as a Smart Object in Photoshop. Select your exposures in Bridge, Then go to Tools> Google >Merge To HDR Efex Pro 2. In the first dialog that comes up for HEP2, there is a check box for “Create Smart Object” It then will continue with Merging and De-Ghosting and then you can if you choose to add tone mapping in HEP2 (some is applied by default) and once you hit OK the image will then open in Photoshop as a 32 Bit File with a Smart Filter Layer with HEP2. This allows for Non destructive editing and the ability to go back to HEP2 for further editing changes and refinements. From There you can save the File in the 32 Bit Format of your Choice, just remember the Smart Filter will not carry over to every other program you may open that file in.

Confusion and Problems

OK so are you confused enough? I’ll take it to the next level of confusion. Working with a 32-bit file is a good thing for the initial stages of making your HDR. However trying to stay in 32-bit or work on a 32-bit image across multiple platforms is where the confusion and problems come in.


The first major problem we come across are Previews.  32-bit images are not viewable on our Computer Monitors – Interestingly the only time you get to see what a 32 Bit image really looks like is when you merge in Photomatix and stop at the 32 Bit Image to save it, there you get to see really how much range there is in the image and why they are not viewable.

Photomatix True 32 bit Display

Photomatix True 32 bit Display

But getting back, since the 32-bit file is not viewable, all programs Tone Map the image down to 16/8 bits to be viewable on your Monitor. Yes, this is Tone –Mapping before you even touch a control. Anytime you convert from one Bit Depth to another that is Tone-mapping. Even when your camera creates an in Camera Jpeg, Tone-mapping is done to take the image from the sensor’s 12-14 bits down to 8 bit.

So a Preview is created to make our 32 viewable. The problem is almost NONE of the previews are the same and the preview will figure into the final image once we do finally convert from 32 bit to 16 or 8 bit final image.

These are 4 preview generated from the same 32-bit Tiff using different programs (Before edit tone-mapping)

Photoshop 32 bit Preview

Photoshop 32 bit Preview

Lightroom 32 Bit Preview

Lightroom 32 Bit Preview

Photomatix Pro 32 Bit Preview

Photomatix Pro 32 Bit Preview

HDR Efex Pro2 32 Bit Preview

HDR Efex Pro2 32 Bit Preview


It’s understandable that different brand software will render the preview differently. But something little known is that even among Adobe Products it is rendered differently. In Lightroom and ACR, a floating bit image is rendered using “Scene-Referred with Linear Gamma” Photoshop outside of ACR renders with Monitor Gamma (I may not be perfectly correct in this statement so correct if you know better) so the two Look VERY different. You can go back and forth between Lightroom and ACR and have the image look the same (Not sure why you would need to) but when that same 32 Bit Tiff is open in Photoshop itself, it looks very different.

The Preview in Lightroom and ACR is not adjustable. However in Photoshop, you can change how the image is previewed. Go to View>32-bit Preview Options.  If you wish to get the two to look similar you may want to try adjusting the 32 Bit preview in Photoshop to +1.0 stop exposure and pull the Gamma down to 1.2. This will get it closer but still not exactly the same (There seem to be some color balance differences too) your results may vary.

32 Bit Preview Options

32 Bit Preview Options

Also, don’t think just because a program previews differently that it necessarily is better then another. Just be aware it happens.

Compatibility in Editing across platforms

This applies to only as long as the image remains in 32-bit and many times people are not still in 32-bit even though they assume they are.

Lightroom to ACR

Compatibility: High.  Make sure you have Lightroom set to also write develop settings to XMP sidecars and not just to the catalog. Changes made in Lightroom will be visible in that 32-Bit Tiff when opened directly in ACR and vice-versa. Just make sure if you are working in ACR and you are finished editing you click done and not open. Open, opens the image in Photoshop but also reduces the image to 16/8 bit depending on how you have ACR set. If you want to go back and forth between LR and ACR just hit done…although I’m still not certain why you would want to given that they do the same thing.

Lightroom/ACR to Photoshop

Compatibility: None. Make sure you understand clearly what I am saying here. This is purely with the 32-bit file. It’s taking a 32-but Tiff, making changes in the LR develop module. closing Lightroom and then opening that 32-bit directly from Photoshop/Bridge. This is NOT right clicking the image and saying “Edit in Photoshop” or Clicking Open in ACR. Doing so will apply the develop settings BUT it will export the image into Photoshop as a 16/8bit image. It is a new image and NOT the 32-bit. So changes you make to a 32-bit Tiff in Lightrrom/ACR will not carry over to Photoshop.

Opening the 32-bit in Photoshop, even though Lightroom is supposed to write those changes to within the Meta of the Tiff even if you push the Meta it is not read by Photoshop and you will not see the Lightroom edits you applied in the develop module

Lightroom/ACR to Photomatix/ Nik HDR Efex Pro 2

Compatibility: None. Again let me make it perfectly clear. This is opening the file directly in these programs, they do not read XMP or Embedded catalog settings so they will not show any edits done in Lightroom or ACR. This is NOT right clicking a Single 32-Bit Tiff in Lightroom and saying “Export to HDR Efex Pro 2/Photomatix Pro” That command will again drop the bit depth to 16/8- Bits depending on your export settings. It’s not working on the 32 Bit file from that method. This is about opening these programs as stand-alones and then opening the 32-bit Tiff, It will not show the LR/ACR edits

Photoshop to Lightroom/ACR Changes made to and saved to a 32-bit Floating Point Tiff in Photoshop will be visible in Lightroom/ACR…HOWEVER because of the differences in Preview between how Photoshop Previews and how Lightroom/ACR Previews, the image almost becomes useless to try and do other editing in Lightroom post working in Photoshop so you really need to watch your workflow here and again I would recommend upgrading to Photoshop CC so you can access the ACR filter from within Photoshop and then do ALL your work within Photoshop
*Edit/Update 6/17/2014* in doing some testing today, I found that while there are some difference in preview rendering, a bigger problem I found was Lightroom Double Processing the Photoshop  image. I will post a separate post about this odd occurrence

How do I know if I am in 32-bit?

Even knowing when you still have a 32 Bit file can be difficult to know. Photoshop does the best job of showing it. In the Image tab that shows the Image Name in the last part of that it shows the Color Mode and Bit Depth.(See the header of the Photoshop Preview image above) You can also Check under Image> Mode for the bit depth the image is in (This is also where you would go to change the Bit Depth when you desire, if it doesn’t happen in some of your other editing workflow such as Export in Lightroom etc). You can  see the Bit Depth of an Image in Bridge in the Metadata panel. In Lightroom I couldn’t find any place that showed the Bit depth of the file, maybe you’ll have better luck.

Working 32-bits is Hard…sometimes

As you can see, while Tone-mapping developing in 32-bit is necessary AND a good thing because you can take advantage of the extra information you may have captured. You can see that trying to work cross platforms is extremely difficult if your goal is to keep the image as long as possible in 32-bit. But the truth of the matter is after a certain point it really is no longer necessary to work in 32-bit and you may be better off not being in 32-bit.

Do all your heavy lifting in 32-bit especially any exposure/highlight/shadow work. That is where the virtues of 32-bit are the best. Once you have as much of that work done as possible then really it’s not a bad thing to convert to 16-bit and continue on with your editing. Since at that point the image is no longer a High Dynamic Range image but rather a standard DR Image (hopefully not Low DR , said with a smile) so don’t sweat not being in 32-bit

All of the major filter and plug-in; Topaz Labs, Nik, onOne etc do not operate in 32-bit color mode so you must be in 16/8bit.  Only about ¼ of all the tools/image adjustments and filters in Photoshop will work in 32-bit so even there, there is just so much you can do

Programs like PTGui, while it can Output a 32-bit really can’t do anything with it after you work on the image in LR/ACR because it doesn’t recognize the XMP

So find a workflow that works for you and stop sweating it but be aware of it.


If you really want to be able to do the most work in 32-bit, the best workflow would be entirely within Photoshop CC (not ACR) because CC is able to access ACR as a smart Filter.

Photoshop Raw Filter

Photoshop Raw Filter

You can do those edits and then do whatever else Photoshop has the capability of doing in 32-bit. But even at that at some point you will need to convert to 16-bit and move on. If you have been hesitant to get in on Photoshop CC for one reason or another, the capability it has to go to the RAW Filter is the best reason to have it

A workflow I will use sometimes when I need the great merging/deghosting power of Photomatix on a difficult to merge image (handheld, lots of tree branches etc) is to Open Photomatix, Open my RAW files from there, click the 32-Bit Preview box, Merge the image and then when the 32-bit pops up save as a 32-Bit file. Then I open that file in Photoshop CC, work it in the Camera RAW filter, make as many adjustments as possible or needed while a 32-bit and then finally convert it to 16-bit (using Image>Mode>16bit which will bring up the HDR Pro interface and then drop it down to Exposure/Gamma and click OK unless you want to use the HDR Pro tone-mapping- I don’t)

When it’s 16-bit I use all the other tools and filters and everything that is now available and then save that file as a new Master 16-Bit file with Layers Intact. But that’s me. Find what works for you


The other main method I use and a lot of people find good is using The HDRsoft’s Merge to 32 Bit Plug-in with Lightroom It works just Great and gives a fast and easy workflow which in the end may be all you need or even the best method.

With that method and without Photoshop being necessary you can select your images in Lightroom, Right Click and Merge to 32 Bit. After the merge the image auto re-imports to Lightroom. Do all your heavy lifting in the Develop Module and then if you want to use 3Rd Party Plug-ins; Topaz, Nik; onOne etc – do so at the last point because Lightroom will now convert it to a 16-bit image and you can finish up your HDR Image. This is the best and most painless workflow and one I use very often.

If you would like to Order HDRSoft’s Merge to 32-Bit Lightroom Plug-in Click this link and enter the Coupon Code THEHDRIMAGE for 15% off your order

OR…simply continue with your current workflow. Like I said at the beginning of this, when you are using a normal Photomatix Pro or HDR Efex Pro 2 workflow you are still working the image in 32-bit while in the Tone-mapping/Fusion Modules so maybe even making a 32Bit Tiff is a waste of time if you are happy with the results you are getting currently. Making a 32-bit Tiff may open up some options for different looks but it may not give you the end result you want or achieve using a more standard workflow for HDR. But hopefully now you will have a better understanding of what people are saying when they say “32-bit HDR” it may not be anything different then what you already had.


  1. Marty November 8, 2014 at 8:16 am #

    Wow, Peter. Quite a lot to digest here … gave it a quick read, and now will have to go back through those bits that apply to my workflows. Thank you for the comprehensive analysis.

  2. Kobus February 17, 2015 at 11:44 am #

    I like my HDR workflow which takes me from selecting the bracketed files in Bridge, merge to HDR Pro, then “Tone in ACR” in 32-bit mode. When finished in ACR it creates a 32-bit Smart filter in Photoshop.

    To do further editing (using brushes, etc.) I am forced to convert the file to 16 bits. How can I save the 32-bit Raw Smart filter for future use?

    • Peter March 9, 2015 at 12:08 pm #

      The only thing you can really do is to Save the File before you down sample it to 16 Bit as a 32 Bit Tiff. But you only have that as a go back to if you needed to fix something before you changed the mode. Unfortunately at this time there is no way to save that 32 Bit smart filter in a 16 Bit file

  3. Michael Maersch November 3, 2015 at 7:23 am #

    I was a bit confused by the way LR (CC-2015) rendered my 32bit (HDR Pro 2) files when I added them into my Catalog. They were ALWAYS quite a bit brighter and more contrasty than I would see within the Nik workspace and/or on-stage in Photoshop.

    HOWEVER, when I simple converted that file into a 16bit file (saving the original 32bit file *for a while because THAT allowed me to return back into the HDR Efex Pro 2 workspace and tweak my settings a bit IF I wanted to*) Lightroom would then render the image PRECISELY AS I was seeing it in the Nik workspace, the PS workspace too.

    By converting that original 32bit file generated by the Nik software THIS PROCESS rendered my HDRI ‘Smart Object’ and I could no longer GO BACK into HDR Efex Pro 2 to tweak my image further there – BUT THEN hell, with a well-affected HDRI *as a 16bit* file one is still able to do spectacular post-production tweaks inside PS, LR or ACR.

  4. Nick November 28, 2015 at 6:41 pm #

    Hi !

    I’m having a lot of trouble when exporting PS hdr files to lower depth pictures. I understand quite well that my 32bit hdr file contains lots more information than a jpeg, and the export would make me lose some of the informations. But what I’m trying to do is to save 8/16bit version of what is simply being displayed on my screen after my light and shadow processing in 32bits (as this screen doesn’t display 32bits anyway). I don’t see a reason why it would not be possible, the white I see isn’t whiter than on a jpg and the black isn’t darker…
    So, when I tick 8bit in my image mode, the whole image is altered and hasn’t anything to do with what I’ve done in 32 bits…
    Is there a single solution to export what I’m seeing on my screen and delete the rest of the information?

    Thanks a lot in advance !

    • Peter November 29, 2015 at 10:45 am #

      Hi Nick,
      There’s a lot of variables here so I’m not quite sure of your total workflow. Ie how you got the 32 bit into PS Via a 32 Bit file made elsewhere, Using PS’s HDR Pro etc.

      But what you want should be possible since what you actually see as you know is NOT a 32 Bit image but rather a Preview in 8/16 it rendered by Photoshop.

      So, the one point in which things can get messed up quite a bit is in the Mode Change to 8/16 Bit. Normally when you have a 32 Bit and you go to change mode a Dialog box will come up with “HDR Toning” It’s this dialog where things go haywire (usually) Make sure when this pops up you drop the method down to “Exposure and Gamma” and you Exposure is set to 0.00 and Gamma to 1.00. This should render what you see in 32bit to what you see in 8.

      But I admit, there are a few other places where things can still go wrong, even in the fact that you can change the rendering of the 32 Bit file in Photoshop and that may not reflect what you see in a another Program like Lightroom since they render previews differently

      Let me know if that helps at all, if not maybe a little more about your workflow,


      • Nick November 29, 2015 at 6:12 am #

        Well, sorry I forgot to mention a lot of details indeed! Actually I’ve always tonemapped in Photomatix but since I wanted to make some more realitic-looking HDR, I have imported the bracketed raw images into PS HDR Pro Merge and the result was excellent. This was for the context I forgot to mention 🙂

        About my problem, the solution you gave me worked perfectly ! In fact the “method” in HDR toning was not set properly and I had to switch it to Exposure and Gamma. Now my 8 bit looks exactly the way it looked in 32 and this is awesome !

        Thank you very much and thanks for the well detailed article above. Great job!


        • Peter November 29, 2015 at 6:24 pm #

          Great Nick!

          Glad I could help out

          Keep shootin!

  5. Charles Hopkins January 19, 2016 at 10:57 am #

    Great article, great info!

    I do have an 32 bit hdr question.
    The short story–
    I use PT Gui 10.0.15 to create 32-bit hdr 360 domes for an automotive client.
    After stitching and output:
    1. 20k 32-bit hdr domes will open in Photoshop CC
    2. 30K and larger 32-bit hdr 360 domes will not open and I get the “could not complete your request because of a problem with the file-format module interface.”
    Are able to shed any light as to why the larger file won’t open?
    Thx in advance!

    • Peter January 19, 2016 at 11:23 am #

      Thanks Charles! Glad you enjoyed the article and found it useful.

      I honestly don’t know the answer to that. but I suspect it may have to do with File size of which Photoshop does have some limitations (and I’m not at all sure that this is what it is)

      But to quote them:
      ?Very large files are often the cause of performance problems. Photoshop supports a maximum file size of 300,000 x 300,000 pixels, except for PDF files, which are limited to 30,000 x 30,000 pixels and 200 x 200 inches.

      File size capability for Photoshop:

      PSD files: 2 GB
      TIFF files: 4 GB
      PSB files: 4 exabytes (4096 petabytes or 4 million terabytes)
      PDF files: 10 GB (pages are limited to a maximum size of 200 inches)

      You may also want to ask a friend of mine who does a lot of 360’s and uses PT GUI This is his website https://www.timothyselvage.com/ Tell him I sent you


  6. Charles Hopkins January 19, 2016 at 11:35 am #

    Hello Peter.

    Thank you for the very timely reply!

    The mystery continues as Photoshop CC will open a corresponding 30k+ .psb with no issues but not that 30k+ .hdr.

    Indeed it does seem that there may be a file limitation/image size preferences thing I’m missing and I’m ALWAYS willing to first say that “I’m probably missing something simple here” before foaming off at the mouth about software and the like!

    I will indeed make use of your suggestion to visit Timothy

    Thank you again and all the best.


  7. Thomas Logan May 31, 2017 at 2:18 pm #

    Yup, late to the party… but, great article, learned a lot. I have been doing the 32-bit thing a long while, just never fully understood it.

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