I was going to write this as a bug over at LHDR’s SourceForge (eek) site, but SourceForge is down (yay) so I’ll post this here in hope that someone knows of a solution.
My biggest issue with Luminance HDR is its lack of support for controlling highlights. That’s one of the core reasons you’d go the HDR route, and yet I know of no solution to recover highlights if a tone-mapping operator blows them. The TMOs work fairly decently on medium dynamic range scenes, but try to process a high dynamic range scene and you have to resort to tricks in other programs to avoid clipping highlights. Let me explain.
Let’s use this HDR as an example, for no reason other than that I just had it open in the browser and it shows the problem ferpectly.
Direct link: http://bit.ly/as-hdr-mpumalanga_veld
Open it in Luminance HDR:
Other than the thermonuclear fusion in the heart of the sun, nothing is clipped.
Try the tone-mapping operators. Let’s use Mantiuk '06 as an example, default settings. Update preview:
The sun and surrounding is completely clipped. Try changing the Mantiuk '06 settings or the pre-gamma, nothing will bring that sky back.
No matter what settings I try for Mantiuk '06, the sun and surrounding sky are always clipped. Looking at the Levels histogram confirms this, see the spike at the right end:
LHDR lacks something as basic as a tone curve (I opened an issue for this ages ago), and using levels is a sure way of clipping things. Click the “Fix color cast” droplet icon - it makes the grass look lovely, but worsens the sky:
Mr Durand does somewhat well:
But you can’t get it from looking like that to looking well in LHDR. Your only option is to save it as a 16-bit TIFF and hope that using curves or other tools in other software can produce a good result:
Mr Reinhard can be used too, if you go the workaround way of using other software:
So the question is: does anyone know of a way to prevent clipping of the brightest areas in a HDR scene in LHDR when using Mantiuk, Fattal, etc?