Old subject....

[helpdesk]

O.k. I have watched the new video's Vlado put up a few days ago. Watched the C.Nichols DVD's AND various other posts in this forum.
Vlado's vids did not show what color space he was running, EXCEPT for the fact I saw him fool around with Reinhard color mapping.
Can't this be easy for crying out loud?
I am using VRAY RC3 on MAX9 32bit.
I am using a calibrated RGB monitor from DELL using SPYDER PRO.
I render out my stills in EXR format sometime HDR, then take it over to Photoshop or Combustion for post work.
What should I be using for Exterior stills? VRAY Frame with linear curve using linear color settings? Reinhard maybe?
Also,What works best for interiors?

This should be alot easier than this!

Dave Vaughn

[Neilg]

It is easiar, stop getting so bogged down with numbers and formulas and just use what looks good.

Interiors, LWF usually looks best. For exteriors however, it depends on the relationship between everything in your scene. Trial and error, learn how each one works in different situations. Reinhard is very good but it dulls everything and kills your whites, so always factor postwork into it.

[Clifton Santiago]

It is easier than this. I don't know why everyone is so confused:

1) Enable your preferences -> gamma/LUT correction. Check Gamma and set at 2.2. Check affect color selector and material editor. Set your bitmap files with an input gamma of 2.2.

1b) Leave your color mapping alone. Default values are fine to start. Later you can use Reinhard or whatever to reduce hotspots.

2) Render to Max Frame Buffer. The image you are seeing is gamma corrected.

3) Save as .EXR (with default "use system gamma" checked) or save as other format with Override set to 2.2.

That's it. You are working in a gamma-corrected linear color space. There are other ways to do it, but this is the simplest IMO.

[helpdesk]

Thank you so much Clifton!! Finally a simple configuration for my workflow!

[tricky]

So the benefit of this method is that in Photoshop I can 're-expose' the image? What profile should be added to this 32bit EXR file in Photoshop, if any? Am I right, or is there something I am missing?


Could you point out the benefits.

[Clifton Santiago]

As I understand it (through trial and error) EXR format is automatically assigned an sRGB profile such that there is no gamma adjustment automatically applied (I guess because it is a 32bit format). As such, when opening an .EXR file it will appear exactly as the rendering in your Max frame buffer*. You can then tweak the exposure settings in photshop CS2 if desired. Also, the gamma is not burned in and can be adjusted for printing for example (Glossy mags want a gamma of 1.8 instead of 2.2).

* Be careful: if you select the "Use RealPixel RGB Data" option, the image may appear brighter than in the MFB.

Or, as I mentioned in step 3, you can save it in any other format if you specify a gamma of 2.2 in the save dialog. This is the equivalent of burning in the gamma with other LWF methods. If you don't, the image will be darkened by photoshop when it applies the sRGB profile. Because these file types are only an 8 or 16 bit image, exposure adjustment will not be physically correct. I use this method for saving TGA files for animations.

The benefit of using this LWF method is you don't have to use the Vray frame buffer curve settings (which I don't think work if rendering to backburner), or gamma color mapping.

This method is basically the third method outlined by Gijs in his linear workflow article:

[tricky]

Blimey - diagrams like that scare me!

So...

Is it therefore a matter of using this LWF method and in effect extracting (as an 8/16bit image) part of the render at one exposure for the majority of an architectural image, but extract areas that are looking 'too dark' at another exposure which brings out the shadows? So it is essentially giving me a lot more 'post production control' over an image production.

[Clifton Santiago]

For something like that maybe use render elements and composite them in photoshop or after effects? If you had your shadows separated from your direct lighting, etc. maybe you would have that kind of control.

In theory though, you shouldn't have areas that are too dark when using LWF because it pumps up your mid-grey range and you see the brightness of your scene correctly. You can then set up your lighting so that your rendering has the correct brightness.

[tricky]

...in addition, by using Max gamma of 2.2 on all bitmaps and colours that are used in textures by default, you wouldn't need to use the ColorCorrect plugin at all - correct?

[Clifton Santiago]

Correct. However, if you are trying to match a specific RGB value, you will need to use the color correct plugin on the color swatch. Either that or use an image map of solid color in your diffuse slot.

[tricky]

When I am sending render jobs to backburner, the image that renders in the max frame buffer is very dark, but seems to be ok when opened in pshop - is this normal behaviour? I guess its because the render nodes are not set up with the correct gamma settings. Is there a way to override this as we often check the status of renders in progress.

[Clifton Santiago]

No that sounds wrong. All your nodes should look the same. The gamma settings are by file, not machine. The only thing is maybe you don't have Load Enable State checked in your gamma prefs?

But I'm not sure, because I never have a frame buffer open on my nodes. I have backburner setup as a service and my nodes are not logged in.

To make sure, evaluate the output. Do a frame or strip on one node and compare to the same on another.

[tricky]

It does appear to be all my nodes where the Max frame buffer renders very dark, but the finished render opens fine in Pshop. Oh well.