[Sidefx-houdini-list] cop's log 2 lin

Ben Schrijvers ben.schrijvers at guerrilla-games.com
Fri Jan 9 13:35:18 EST 2009


No it's more than 8 bit. Though every bit counts in a game engine so in 
the actual buffer might be more than just Z.
But I believe this dump image is already processed somehow to stip a 24 
bit depth value (first 3 bytes) from a 32 buffer.
It was a .dds file that I loaded into Photoshop and saved as 32 bit tiff 
file.

Apart from the "adapt" I also found the histogram to be handy.
My values now (after calculation below) go from 1 to 50 which sort of is 
correct for this shot.

cheers,
benS


Peter Robbinson wrote:
> I wouldn't expect a log image in a game engine, and it will likely be 8 
> bit as well won't it?
> When you MMB on one of the cop nodes, what's it telling you?
>
> PeterR
>
> Ben Schrijvers wrote:
>   
>> No I'm looking at a Z-buffer of our game engine.
>> Not even sure if it's really a log image and the coder went already home 
>> or are getting drunk downstairs :-)
>>
>> I've found that it looks a lot better when I do:
>> 1 / (1-image)
>>
>> cheers,
>> benS
>>
>>
>> Andrew D Lyons wrote:
>>   
>>     
>>> Is this the kind of image you are dealing with?
>>>
>>> http://www.imagemagick.org/www/motion-picture.html
>>>
>>> I'd guess you would need to know the black point,white point, and
>>> gamma with which the image were encoded...
>>>
>>> Cheers
>>>
>>>
>>>
>>> 2009/1/9 Ben Schrijvers <ben.schrijvers at guerrilla-games.com>:
>>>   
>>>     
>>>       
>>>> Hi there,
>>>>
>>>> In COP's how do I convert from a log image to a linear image?
>>>>
>>>> I've found a log(x) function in the Function Cop but somehow that gives
>>>> me negative values.
>>>> But that probably the wrong way around in that it's lin to log.
>>>> So what's the inverse? Obviously I've got now idea what I'm talking about...
>>>>
>>>> cheers,
>>>> benS
>>>>
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>>>>       
>>>>         
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>>>     
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>
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