What is your background?
Half Life 1 modder turned Archviz / BIM :)
My first introduction to 3dsMax was Autodesk Gmax, because Milkshape 3D was lacking a lot of features.
from adobe page
In Photoshop, the luminance values of an HDR image are stored using a floating-point numeric representation that’s 32 bits long (32‑bits-per-channel). The luminance values in an HDR image are directly related to the amount of light in a scene.
I've posted examples all over the forums for years, but I guess it's best I recap everything here.
I'm running the latest version.
![](https://i.imgur.com/ICyhJtr.jpg)
#1
If you go back a few pages and download my ACES tonemapper script for Photoshop. You will notice that bright lights becomes black pixels. This is because Photoshop does not calculate negative values.
The script will split your render into two images and then divide those images together. Photoshop does not handle negative math well, and will return black pixels.
#2
Corona Sun
![](https://i.imgur.com/ysrpjvJ.jpg)
Corona Sun rendered as HDRi and re-saved in Photoshop as EXR.
Goodbye values.
![](https://i.imgur.com/Mps9YOw.jpg)
Corona Sun rendered as HDRi and re-saved in Photoshop as HDR.
Better than EXR, still not what we expect.
![](https://i.imgur.com/9SYxpai.jpg)
#3
32bit floating point displacement.
Proper 32bit map rendered in Corona
![](https://i.imgur.com/BicgHVr.jpg)
Re-saved in Photoshop as EXR.
Since this map does not exceed 20 Photoshop Intensity, it will not clip.
Negative values work as intended also.
![](https://i.imgur.com/6kmkmvX.jpg)
Re-saved in Photoshop as HDR.
Since this map does not exceed 20 Photoshop Intensity, it will not clip.
But since it's HDR, it will not have negative values.
It also has some weird ass shadow artifacts.
![](https://i.imgur.com/10zUDWO.jpg)
So if you use Photoshop you are left with these choices:
EXR: Clamped bright values and clamped negative values.
HDR: Somewhat proper bright values and no negative values.
Internal: Can't do negative math.
I bugged Adobe back in 2016 about this problem. They said they didn't understand what I meant about clipped values above +20 RGB, and asked me to take a print screen of the problem. (I had provided renders like the ones I posted here, but they wanted a print screen of the HDR image) That is when I gave up.