Is it possible that you have different default settings in Lightroom than in Camera Raw?
I've just run a set of images back through the process. In the Merge to HDR Pro window I ensured that default settings were elected from the drop-down in the top-right. In Camera Raw I ensured Camera Raw Defaults was selected under the Presets panel. As far as I can tell none of these settings have been altered… but if there is a way to confirm this I will happily go through any processes to confirm.
As you can see in the following screenshot the new images looks very overexposed in Lightroom, but not so in Photoshop.
I've found the option to reset the develop settings in Lightroom… in there a way to do this in Photoshop to in order to completely rule this out?
What you’re seeing is NORMAL when viewing a 32-bit HDR images because of the different internal profile each uses for mapping HDR images to the screen color space. What you see on screen isn’t the 32-bit image, it is the 32-bit image mapped to the screen and each uses a different method for doing this. You may see something similar to LR’s rendering in PS if you use the Camera Raw Filter for toning. The only way to make them the same is to convert to 16- or 8-bit images from the 32-bit floating point HDR.
Ok, that makes sense! I've only recently started playing with the HDR functionality.
So, after reading about 32-bit and 16-bit files online I've become no clearer on whether is it actually more beneficial to keep the image as a 32-bit image once I have completed the Merge to HDR Pro process. With I'm 32-bits I'm assuming more data per pixel, more accurate colour and thus better image detail. So if I convert to 16-bit then I loose image quality? I've also noticed that I can't go back and pickup work on a camera raw filter with a 16-bit image. That's a bit of a killer for me.
It seems a little mad to me that Lightroom doesn't support 32-bit images when Photoshop does, particularly given they're designed to be used together. Are there any popular plugins to introduce support?
Finally (sorry for all the questions!), is it because the image I was working with is 32-bit that I can't find an option in photoshop to export a JPEG?
A “raw” HDR image has darks that are too dark to see detail in and lights that are too bright to see any detail in. The process of “tone mapping” is what scrunches all the floating point values into the normal range of black to white. Once an image is tone mapped its pixel values all fall into the range of zero to whatever the maximum value is for white in a 16-bit or 8-bit format and it can be saved as such. The 32-bit floating point image is supposed to be temporary on the way to an 8- or 16-bit image. Personally I save the original 32-bit image in a separate file from the tone-mapped 16- or 8-bit image so I can always go back and revisit the tone mapping operation.
LR supports 32-bit images otherwise you would see nothing. Here is a discussion about why things look different that includes Eric Chan, an Adobe Raw Engineer, to someone bringing up a similar concern a little over a year ago:
It used to be that Photoshop was the only Adobe product that could open 32-bit files and tone-map them to 16- or 8-bits and I would argue that it did an unsatisfying job. Eventually this capability was added to LR and the ACR plug-in for Photoshop which does a better job, but being raw converters, the starting point looks brighter on screen.
Photomatix is a payfor product that also does a good job with both merging and tone-mapping to 16- or 8-bits. It comes with both a standalone and a plug-in interface. There are others, but Photomatix is the one I’ve tried in the past.
Excellent, thanks for that. Glad that I finally understand what's going on!