Poser Pro Gamma

This document covers optimizing renders for High Dynamic Range output including: getting started, exporting the render, and Working in Photoshop.

For an overview of what High Dynamic Range Imaging is please visit:

HDRI or High Dynamic Range Imaging is exists in Poser Pro in two forms. First in the included light sets you'll see that there are HDR Image based light sets available to be dropped into scenes such as those based on images supplied by HDRVFX. This tutorial however will relate to optimizing renders for HDR output and using that output in Photoshop CS3.

Requirements
Poser Pro is required, other versions of Poser do not support HDRI optimization and output. Photoshop CS3 is recommended however any image editing application that supports High dynamic range images can be used.

getting Started

Start by penning the Render Settings dialogue. Switch to Manual settings and change your settings to match the following:

Notice that in the bottom right corner there’s an HDRI Optimized Output button.
We’re going to check this and leave it on. This will optimize the output file for High Dynamic Range. In the end we’ll get an image that has a depth of 32bits per channel.

Let’s look at a test file. You can build your own easily by dropping any two characters into a scene and placing one behind and to the left of the other as shown below. You may want to follow the tutorial with the supplied HDRI_Tutorial.pz3.

Now do a render with the current render settings and you should see something like the following:

Exporting the Render

Let's first export the render as .jpg and then the same render as a .HDR file. To do this click on the export image icon at the top of the Render Preview window in the Poser Pro UI. Then select the format you wish to export to.

It's important to not that you are viewing a preview of the render and that this preview is gamma corrected yet when you view a .hdr file or an open .exr file in another application, there will be no gamma correction applied to the image being viewed. This is because when Poser exports the .hdr or .exr file, no gamma correction is applied.

Working in Photoshop

Now let’s edit the files in Photoshop CS3. You can use any other application that imports .hdr files and allows you to adjust the exposure and gamma settings of an image.

When opened in Photoshop you should see something like the images below:

In the .jpg image is on the left and the .hdr image is on the right.

Notice that the HDRI image does not have gamma correction applied to it so it looks different after export than it does in the Render preview window of the Poser Pro application. This is because. The .hdr file is set to a gamma correction of 1.0.

The image on the left is the render preview window and is gamma corrected,
the image on the right is the exported.hdr file opened in photoshop.

The easiest way to visually demonstrate the difference between the jpg image and the hdr image is to try to adjust the exposure and Gamma to bring the very dark background figure out in the jpg image.

If you look at image 1, the adjusted jpg, you’ll notice that before I can get the background figure anywhere near the needed brightness, a posterization type effect occurs in some areas. Especially in the metallic reflective areas of the helmet.

Now look at the results of the hdr image. We are able to adjust the exposure on the background character and the foreground character to better match them.
This was done by selecting the background are an character with Photoshop’s Quick Selection tool. The selection has been saved into the James.psd for your convenience, and then adjusting the exposure of each character separately. Incidentally this was also attempted for the jpg image in the same manner.

That is with the selection however because the bit depth of the jpg is 8 bits per channel and not 32bits per channel, it is all but impossible to do this. Optimizing renders for High Dynamic range output offers an incredible amount of versatility.