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#Actualvidel

Posted 16 August 2012 - 03:37 AM

@jefferytitan Yes I got the information about the geometric mean from the blog post you mentioned.

To calculate the geometric mean, I simply calculate the log of luminance and write the results to a 1024×1024 texture. I then call GenerateMips to automatically generate the full mip-map chain. At that point I can apply exp() to the last mip level to get a full log-average of the scene.



That's exactly what I am doing right now (except I am downsampling using custom shaders and not the mip mapping function). I am not sure which base I should use for the log and exp. Default log and exp functions are using e. Somehow there must also be a error in my code, using the geometric mean the exposure control does really not help to brighten dark areas. But it works using the arithmetic mean...

@MJP
Ok, separating exposure control and tonemapping makes sense. I've also read the article on John Hable's Blog. He does also separate the exposure correction and the tonemapping I think.

In your demo application (which is very useful ;)) you have a slightly more advanced algorithm to control the exposure. You do also use the geometric mean, right?
Controlling the mood is essential yes. In your application that is the keyValue slider I suppose.

I will take a look at this book, I've already found two of the presentations and your blog article before ;)

#1videl

Posted 16 August 2012 - 03:37 AM

@jefferytitan Yes I got the information about the geometric mean from the blog post you mentioned.
"To calculate the geometric mean, I simply calculate the log of luminance and write the results to a 1024×1024 texture. I then call GenerateMips to automatically generate the full mip-map chain. At that point I can apply exp() to the last mip level to get a full log-average of the scene."

That's exactly what I am doing right now (except I am downsampling using custom shaders and not the mip mapping function). I am not sure which base I should use for the log and exp. Default log and exp functions are using e. Somehow there must also be a error in my code, using the geometric mean the exposure control does really not help to brighten dark areas. But it works using the arithmetic mean...

@MJP
Ok, separating exposure control and tonemapping makes sense. I've also read the article on John Hable's Blog. He does also separate the exposure correction and the tonemapping I think.

In your demo application (which is very useful ;)) you have a slightly more advanced algorithm to control the exposure. You do also use the geometric mean, right?
Controlling the mood is essential yes. In your application that is the keyValue slider I suppose.

I will take a look at this book, I've already found two of the presentations and your blog article before ;)

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