Hello John,
> Thanks for the great images, and for explaining some of your technique. I
> have been exploring HDR panoramas using PhotoMatix for some time now, but
> very interested in some of these other tonemapping algorithms. I am just
> wondering what software you used to apply the Photoreceptor algorithm.
Besides the binary from the book "High Dynamic Range Imaging" which i used, because i built my workflow around it (drag'n'drop style), there are 2 software packages i am aware of:
Artizen offers an additional photoreceptor plugin.
Picturenaut has a builtin photoreceptor TMO.
> I
> have been playing around with Artizen HDR, and am really impressed with
> the
> tonemapping algorithms, but it lacks the 360-degree option to ensure the
> +/-
> 180 degree locations match up. So I have been seeing issues with different
> values along the left/right resulting seam (though the nadir and zenith
> are
> coming out great, which I had some issues with in PhotoMatix). How do you
> use these (great) algorithms, and get over the wrap seam issues?
Only "local" operators have serious seam issues. Photoreceptor is a global(-style) TMO. The parameters depend on global min/max brightness and the HDR is consistently mapped proportionally in all image regions, so there is no (big) need to care about the 360-degree boundaries.
You can still try to work around seam issues by placing no bright lights over or near the seam. This should "calm down" the the values befor entering the seam area.
To add an IMHO important word about operators:
Photomatix has also a builtin global TMO set, but that one is a "photographic" style. To explain the difference in a not very technical way:
The photographic TMO - and many other - map down the DR to a viewable range leaving color information intact. The photoreceptor TMO does mimicry the exhaustion of the eye's light receptors. If you look into bright light, the receptors quickly consume most of their deposited chemical raw material to generate the electrical impulses. This not only makes the receptors less sensitive for light (resulting in a wider dynamic range "seeable" in one go), it also reduces sensitivity for colors. So, IMHO, the photoreceptor TMO produces the most natural viewing experience.
Still though, one may find untouched photoreceptor-mapped images a little dull. In most of my images, i use an unsharp mask to increase microcontrast. This reduces the viewable DR to some extent (lights "burn out" earlier) but make the images look more pleasing.
Best regards
Bernhard
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