[Radiance-general] Images too bright with gendaylit

[Guglielmetti, Robert]

On 8/8/17, 11:50 PM, "Joe" <solarjoe at posteo.org> wrote:

>
>Does pcond -h something like automatically calculate the maximum
>luminance
>and adjust the exposure? Or will it also apply the different perception
>of red, green and blue?


Something like that, yeah. When low-luminance scenes are detected (by
inspecting the pixels’ values), the loss of color acuity is modeled.
Disability glare and veiling reflections are modeled as well. The exact
goings-on are detailed in Chapter 7 (Roadway Lighting) of the Rendering
with Radiance book, and the -h option to pcond is simply a combination of
luminance-based tweaks to the pixels, discussed in that chapter. The
output images lose all validity at the pixel value level, but they make
for compelling images on low dynamic range displays.

You will definitely want to look at Rob Shakespeare’s work (he’s
presenting an update at this years’ Radiance Workshop) with using Radiance
images and tone mapping to simulate scenes as perceived by aging eyes.
It;s awesome stuff, and a great illustration of the value of Radiance
images and the tools used to create and analyze them.

>Is there a parameter for rvu to automatically set the exposure using the
>maximum Luminance
>calculated?


In rvu you can hit ‘e’ and the pick a point near where you know max
luminance to be and it will scale the exposure accordingly, albeit
linearly. You can also use ‘pextrem’ at the command line to get the
maximum and minimum pixel values (and x,y locations) of an input image.
Another utility you may be interested in is ‘phisto’, which will create a
histogram of a series of input images and supply a value you can use to
expose the input images uniformly (sorta).

- Rob