[HDR-photo] Why does the preview look better than the finaloutputimage?

[Geraldine Joffre]

On Fri, 30 Mar 2007 06:20:23 -0500, Ferrell McCollough wrote
> The Strength and Light Smoothing sliders have a profound effect on 
> the image. Pushing these sliders to higher values can cause the 
> preview to look different from the final rendering. At Strength 
> values near 100 and Light Smoothing near -2 the image has the least 
> global contrast and the highest local contrast. That means the 
> greatest compression is taking place over the smallest region with 
> only partial pixel information provided by the preview. As these 
> values are increased the preview look will stray further from the 
> final product, all compounded by a larger file size.  So try to 
> lower the strength a little bit and raise the Light Smoothing value 
> a notch. For example, instead of Strength=90 and Light Smoothing= -1 
> try Strength=75 and Light Smoothing = +1 I think you will find a 
> much closer rendering.
In the case of Light Smoothing, this is the reverse actually. The lower the
value of the Light Smoothing setting, the closer the preview will be to the
final output. When Light Smoothing is set to +2, the risk of divergence with
the preview is the highest.
 
> Also, choose to preview at the highest resolution - 1024.
Yes, this is a good point.
 
> Geraldine may want to respond to the 100% crop option. It's good for 
> seeing local enhancements but can it be used to get a glimpse of the 
> image at full resolution, ie. in the final rendered state?
Not in the case of the Details Enhancer method unfortunately. As the note says
when you click on the magnifier icon with Details Enhancer, the 100% crop only
gives you an idea of how the local details will be enhanced. This is useful to
spot problems of noise for instance, and check whether adjusting settings such
as Micro-smoothing can reduce or eliminate them. The brightness level of a
crop of the tone mapped image at full resolution can only be known by
processing all the other pixels of the image. 

Geraldine Joffre