Re: [Openexr-user] OpenExr >=16bit editor

[lists]

On Jul 8, 2004, at 6:47 PM, Chris Cox wrote:

> At 5:47 PM +0200 7/8/04, Jan Woetzel wrote:
> > Hi,
> > Can you suggest an image editor that can really paint 32bit (or at 
> > least 16 bit), ideally with OpenEXR support?
> >
> > I am saving my (natively 32 bit) maps in OpenEXR 16 bit format and 
> > want to retouche them.
> > I tried Photoshop 6.0 (with the OpenEXR plugin), but the editing 
> > tools seem to support 8 bit, only.
> > Hope my question is not too off-topic, but I will write an OpenEXR 
> > converter for that tool if really required.
>
> Photoshop CS supports 16 bit tools, layers, etc.

Keep in mind that if you are using expanded dynamic range images (which 
is possible with 32 bits), the EXR plugin for photoshop reduces the 
dynamic range (if any) of your source images to 8-bits per channel by 
default, with no float for expanded range. This is why the plug-in asks 
you to determine the gamma and exposure settings for the "slice" of the 
image range you want to open. If you then save this edited file back 
over the existing EXR, it will still be EXR format, but missing all of 
the other "exposure slices." You are essentially "flattening" the range 
of your EXR image by opening it in Photoshop.

This is the same thing that happens when you open an exposure from 
HDRshop in Photoshop. Photoshop is simply a low dynamic range image 
editor. The 16 bits per channel it can handle does not include any 
greater dynamic range, only finer subdivisions of the range you already 
have. Caveat Productor. (noticed your email domain...)

So, keep this in mind whenever using Photoshop or other low-dynamic 
range editors. CinePaint is one of the few high-dynamic range image 
editors out there, and free. Unfortunately, CinePaint has had many 
problems editing and saving various types of EXR images. This may have 
been fixed by now, but I'm not aware if it is in the general release. 
Nice app, otherwise.

-Mark