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

[Gabbygall]

HI Ferrell (interesting name, never met a `Ferrell` before)

I understand what you are saying, but the problem is the fact why even
bother with a preview when the final image looks NOTHING like it.. I think I
may need to post some examples on here, the preview is `perfect`. The final
output isn't.. its just so annoying.

Bottom line is, I would rather the final image look like the preview, than
try to tweak the preview to look more like the final image.

If that makes any sense  (on my 2nd bottle of wine here!)

-----Original Message-----
From: hdr-photo-bounces at hdr-photography.com
[mailto:hdr-photo-bounces at hdr-photography.com] On Behalf Of Ferrell
McCollough
Sent: 30 March 2007 12:20
To: High Dynamic Range Photography
Subject: Re: [HDR-photo] Why does the preview look better than
thefinaloutputimage?

Hi Gabbygall,
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.

I've noticed an increase in color saturation after processing. As a result I

adjust the color saturation I like in the preview then I drop it back about 
10%. Also remember color saturation can be reworked in post processing so 
you can be conservative in Photomatix.

Also, choose to preview at the highest resolution - 1024.

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?


Ferrell





----- Original Message ----- 
From: "Gabbygall" <gabbygall at btopenworld.com>
To: "'High Dynamic Range Photography'" <hdr-photo at hdr-photography.com>
Sent: Thursday, March 29, 2007 1:03 PM
Subject: RE: [HDR-photo] Why does the preview look better than the 
finaloutputimage?


> Hi Geraldine,
> That's all well and good, but its still incredibly annoying, and unless I
> resize quite a lot (I shoot with a 12mp sensor) then it doesn't look like
> the preview at all. I like the preview. Its usually better than the final
> `rendering`.  Will this be fixed?
>
> -----Original Message-----
> From: hdr-photo-bounces at hdr-photography.com
> [mailto:hdr-photo-bounces at hdr-photography.com] On Behalf Of Geraldine 
> Joffre
> Sent: 28 March 2007 11:22
> To: High Dynamic Range Photography
> Subject: Re: [HDR-photo] Why does the preview look better than the
> finaloutput image?
>
> On Tue, 27 Mar 2007 14:13:04 -0700, Bob Wise wrote
>> Thanks Geraldine... I'm not quite sure I understand.
>>
>> Are you suggesting to:
>>
>> 1) Upres the image
>> 2) Run the HDR processing
>> 3) Down-res the image?
>
> The suggestion of resizing the HDR image slightly was for the special case
> when the final result is very dark and way different from the preview. In
> this
> case, the suggested workaround would be as follows:
> 1) Generate the HDR image at the original resolution
> 2) Down-res the HDR image in Photoshop by a small amount
> 3) Tone map the resized HDR image
>
> The purpose of resizing in this case is to get rid of the abnormally low
> values (which are confusing the Details Enhancer algorithm) thanks to the
> interpolation done when resizing.
>
> For the general case of the final result looking different from the 
> preview,
> I
> was just pointing out that the algorithm is the same in both cases but the
> image that is being tone mapped is different. The preview shows the result
> of
> the tone mapping applied to a low-res version of the original HDR image. 
> The
> low-res version does not contain the same pixels as the original version 
> of
> the HDR image. Given that Details Enhancer takes into account local 
> details
> throughout the image, it is likely to map the low-res version of the HDR
> image
> differently than its original version.
>
> The largest the difference in resolution, the more different the mapping 
> is
> likely to be. This is is why downsizing the HDR image to get closer to the
> preview resolution should reduce the difference between the tone mapped
> preview and the final tone mapped output.
>
> Another workaround is to use the tone mapping method Tone Compressor 
> instead
> of Details Enhancer. Tone Compressor maps each pixel independently of the
> local context, making the preview a reliable representation of the final
> result.
>
> Geraldine Joffre
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