At step 4, I expect it to be different. You're telling it to apply an anti-gamma of 2.2. Whereas in step 3 it used 1.0, because the default gamma for HDR images (incoming) is 1.0. I know the stupid dialog claims "Use Render Settings", but that's not what it does with HDR images. Instead, it uses 1.0, as it should. The render gamma is not correct for an incoming HDR image, so it doesn't use that.

The first choice "Use Gamma value from Render Settings" has the wrong name. It should be called "Use appropriate value automatically." For HDR images that is 1, regardless of what the render gamma is. When the render gamma is 2.2, and the incoming image is a JPEG, the correct default value is 2.2, which happens to be the same.

It turns out, however, that when the render gamma is anything other than 2.2, such as 1.8, but the incoming image is a JPEG in sRGB color space, the incoming gamma should be 2.2.

In other words, choosing to use incoming gamma = outgoing gamma is only the right choice when the outgoing gamma actually is the gamma of the incoming image. Any other time, it's the wrong value.

Poser assumes the incoming gamma of HDR and EXR images is 1, and you don't really want to match the render gamma of 2.2. The point of the image gamma is to linearize it.

Note - after choosing an image, if the first radio button is active, the value shown in the second ("Custom Gamma") actually reveals what is being used. Choose an HDR or EXR and it says 1.0. Choose a JPG and it says 2.2.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)