POV-Ray : Newsgroups : povray.general : new free HDRI Server Time
2 Aug 2024 04:23:11 EDT (-0400)
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From: Christoph Hormann
Subject: Re: new free HDRI
Date: 13 May 2005 04:15:02
Message: <d61niu$33b$1@chho.imagico.de>
Chris Cason wrote:
> 
> I just installed KDE 3.4 on FreeBSD 5.4 and FreeBSD automatically installed
> OpenEXR along with it (it is used by KDE, though I don't think it is a
> requirement).

kimgio includes read support for OpenEXR (so all KDE apps using standard 
mechanisms for loading images can read it, only in 8bit of course, if 
KDE is built with OpenEXR).  Note however konstruct (the tool to build 
KDE from source) does not install OpenEXR as a dependency so you have to 
explicitly install it before building to have it supported.

Christoph

-- 
POV-Ray tutorials, include files, Sim-POV,
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From: Warp
Subject: Re: new free HDRI
Date: 13 May 2005 09:35:39
Message: <4284ad2b@news.povray.org>
Alain <ele### [at] netscapenet> wrote:
> Think of 48bpp png as "extended dynamic range".

  I thought that the "dynamic" part referred to the fact that the
format uses floating point numbers (which can scale dynamically to
bigger ranges by changing the exponent part of the number). PNG only
uses integers which are mapped linearly, so there's no dynamicity
there.

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                                                          - Warp


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From: Vincent LE CHEVALIER
Subject: Re: new free HDRI
Date: 13 May 2005 11:39:48
Message: <4284ca44@news.povray.org>
Warp wrote:
> Alain <ele### [at] netscapenet> wrote:
> 
>>Think of 48bpp png as "extended dynamic range".
> 
> 
>   I thought that the "dynamic" part referred to the fact that the
> format uses floating point numbers (which can scale dynamically to
> bigger ranges by changing the exponent part of the number). PNG only
> uses integers which are mapped linearly, so there's no dynamicity
> there.
> 
I think precisely that what Alain meant was that while 48bpp offers a 
greater dynamic range than 24bpp (namely 511:1 instead of 255:1), it is 
far from being truely "high dynamic range" (the dynamic is 10e38:10e-38 
for .hdr, 65000:0.0000012 for .exr)...

-- 
Vincent


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From: Christoph Hormann
Subject: Re: new free HDRI
Date: 13 May 2005 12:05:01
Message: <d62j42$ap2$1@chho.imagico.de>
Vincent LE CHEVALIER wrote:
> I think precisely that what Alain meant was that while 48bpp offers a 
> greater dynamic range than 24bpp (namely 511:1 instead of 255:1)

That's more likely 65535:1...

Christoph

-- 
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 03 May. 2005 _____./\/^>_*_<^\/\.______


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From: Vincent LE CHEVALIER
Subject: Re: new free HDRI
Date: 13 May 2005 14:26:42
Message: <4284f162@news.povray.org>
Christoph Hormann wrote:
> Vincent LE CHEVALIER wrote:
> 
>> I think precisely that what Alain meant was that while 48bpp offers a 
>> greater dynamic range than 24bpp (namely 511:1 instead of 255:1)
> 
> 
> That's more likely 65535:1...
> 

Wooops indeed, I should avoid posts on friday the 13th ;-)
Well anyway you got the idea : 255:1 < 65535:1 < 65000:0.0000012 < 
10e38:10e-38, in terms of dynamic range. While precision and 
quantization would be another issue...

Thanks for correcting anyway :-)

-- 
Vincent


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From: Fredrik Eriksson
Subject: Re: new free HDRI
Date: 13 May 2005 18:43:20
Message: <op.sqqj60cgcs6ysw@frogeater.bredbandsbolaget.se>
On Fri, 13 May 2005 09:16:16 +0200, Christoph Hormann  
<chr### [at] gmxde> wrote:
> The libraries are certainly not the problem.


Leaving the parts I've written myself...



>> If there is sufficient interest, I might make the effort to clean up  
>> the  code and release the source, but otherwise I just don't want to  
>> bother.
>
> Well - if the program is working well there for sure would be interest.


Depends on your definition of "well", but I see your point.

I guess it comes down to my own interest then; whether I can find the  
motivation to make the code presentable enough for release.



-- 
FE


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From: Fredrik Eriksson
Subject: Re: new free HDRI
Date: 16 May 2005 21:41:53
Message: <op.sqwcgufhcs6ysw@frogeater.bredbandsbolaget.se>
All right, I've tinkered enough with this thing now. I really don't feel  
inspired enough to continue work on the program right now, so I'll just  
release it as it is, in case anyone finds it useful.

For those that haven't been following this discussion, 'hdr2exr' is a  
program that converts image files to/from HDR, OpenEXR & PNG.

Source (excluding support libraries) at:
http://hem.bredband.net/b230591/hdr2exr/hdr2exr_source.zip

Precompiled Win32 binary at:
http://hem.bredband.net/b230591/hdr2exr/hdr2exr_win32.zip

Example image in all supported formats at:
http://hem.bredband.net/b230591/hdr2exr/hdr2exr_examples.zip



-- 
FE


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