View Full Version : RGBA 32bit vs RGBE 8bit

06 June 2010, 09:09 AM
Hi there;

What is the diference between EXR RGBA 32bit format and EXR RGBE 8bit format?, both opened in photoshop are read as 32 bit float images, the only difference is RGBE has no alpha info...

Thank's for the answers :)
06 June 2010, 02:57 PM
RGBE is the ward radiance format. in E you have a shared exponent ... to turn the 8bits RGB channels into 32bits ...

if (rgbe[3]) {
f = ldexp(1.0,rgbe[3]-(int)(128+8));

*red = rgbe[0] * f;
*green = rgbe[1] * f;
*blue = rgbe[2] * f;


06 June 2010, 04:37 PM
OK, it's an exponent..., so, is it the same to render 8bit RGBE as to render 32bit RGBA EXR format?.

06 June 2010, 09:56 PM
umm think of it as 8bit on steroids

haha , i like that!

06 June 2010, 09:56 PM
No, RGBE will not give you the same range like 32 or 16 .
but you can get away with it in some situations
umm think of it as 8bit on steroids :)

07 July 2010, 11:16 AM
As RGBE doesn't have any alpha information..., Wich pass should I use to get one?, I've tried "matte" and "opacity" passes but both of them come black.

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07 July 2010, 11:16 AM
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