@David Brinnen & Horo
Thank you for inviting more people to this discussion. It’s indeed interesting to know other opinions in this subject.
That gamma thing is indeed very deep subject. It’s the feature that would be useful for more advanced users wanting more control on the lighting and integration with other mediums. I think there’s a place for this function in the future versions of Bryce (with more control over it via additional options). I can see the big number of material libraries created by you with no gamma in mind. I think I wouldn’t convert them to be used with gamma and wouldn’t make the new libraries for the gamma correction on as currently that would cause the confusion and the future versions of Bryce may bring automatic conversion for colour swatches and colour textures. Yeah, that would be nice feature request. I can think of a GUI mockup that might have these options.
I’ve noticed that gamma correction turned on is extremely useful option when you use IBL, TA and reflections in your scene, otherwise it doesn’t have such strong impact. Also gamma correction doesn’t have to make your image washed out, you simply can ‘inverse correct your colours’ while still using gamma. Speaking the easy way it’s done by making all colour swatches and bitmaps in the scene darker and more saturated, and speaking the more difficult way use the formula: ((colour/255)^1.585)^255 on each of the colour component (including lights and sky elements) and using gamma filter with value of 0.631 on your colour bitmaps.
About your images…
I like more on the first one:
- the vegetation (colours, light response)
- the mom’s clothes (colour and light)
- the mom’s left hand (fist) and angled right hand’s finger (on the second picture she looks more like she was laughing out from the kid)
- light under the gate’s arch and less intense shading of the bump.
- shadows of the left hand - because of making the shadows lighter on the second image they’re almost non existing under the palm
and on the second one:
- mom’s face colour and ground colours (they look more like the creator of textures intended them to)
- fog on the background (it’s not going to almost fully white)
- softened shadows
Thank you again for the test that confirmed that Bryce applies gamma of 1.585 over the rendered image. The observed slowing down was also interesting point to not use gamma and render instead to *.hdr and apply it in the post.
I think it’s not handy to use it often at the current form, considering all colours would have to be corrected, so I understand why you don’t like it. Anyway I’m still sticking to using it and I’m going to try out new ways of generating HDR’s out of the scene in a single run by using the sphere mapper, and Bryce ability to save images of greater depth than displayed.
You’ve got an eye for the things. Without gamma you get more contrast in light and shadow (it’s really evident when lighting interior scenes when using TA). Using Brycean gamma with colours corrected to be darker is more realistic, although still not fully realistic from mathematical point of view. To be more mathematically correct you’d have to apply the inverse gamma of 2.2 to all of your colours and bitmaps but current colour sliders (having 0 to 255 range) can’t really handle it. Gamma of 1.585 is a good compromise.
Here’s my example with using gamma without washing out the texture colours. She scene consists of:
- infinite plane
- 3 terrains forming the cave (slightly modified stalactite pro material)
- glass sphere (refraction only)
- sky turned into hdr for finer control with opacity of 75% blended with flat sky colour, atmosphere is turned off
- sunlight (very pale peach-orange, 100% intensity of shadows)
- mid cold blue ambient making the stone material glow with 20% strength (only for scenes 1, 2 and 3)
- orange point light with inverse square response
It’s rendered wit relativity low TA samples (9) and number of bounces (3)
1. A scene with gamma correction off, ambient appears slightly like a fog giving some light to dark areas. Ambient in TA mode does not appear that flat - it rather looks for me like some kind of inverse ambient occlusion. Notice burned out directly lit areas as well as hdr background.
2. The same scene as 1, gamma correction option is on, I used the formula that I’ve written above for fixing colours to appear the same with gamma used. All colours swatches were fixed - including the ones for lights, ambient, and those inside the procedural texture, no light intensities were changed. You can see softer distribution of lights (no burning out to white at the parts of the cave exposed to direct light).
3. The example pushed further than the Bryce allows in default workflow. The colours were corrected from 1st example - now by inverse of 2.2 gamma, and so was the final render. Now you can see that ambient materials are really glowing, and that ambient light is bouncing around and polluting the whole scene.
Side note: I rendered the image with gamma correction option turned on + some more, remaining gamma was added in the raster image editor (I could also render with gamma correction off, save as *.hdr and apply gamma in the editor that opens *.hdr images). The process of degammaing your inputs and applying 2.2 gamma on your final image is called sometimes linear workflow. Options to make it easier to follow and more automatic are often incorporated in modern graphic applications.
4. The scene from the 1st example. I removed ambient colour from the sky settings and from the materials and made the sunlight stronger (135 from 100), HDRI effect from 20 to 25, and intensity of orange light inside lowered from 50 to 25 (as it appeared too strong for me for such lighting conditions outside). Despite the TA turned on, and such strong light outside you can’t see almost anything in dark areas of cave.
5. The scene from 4th example with tweaks as described in 2nd example. This is looking quite realistic already, I really like that setup.
6. The scene from 4th example with tweaks as described in 3nd example. Not that strong difference from 5th example, a bit more light in the shadows and it’s more physically correct.
7. I decided to push 6 further. With some colour corrections and slight noise removal I made the version that I really like. It’s more comparable with its dynamic range with 5th example but the light areas of the stone became silky-smooth and the shadows are more saturated now.
8. Bonus scene - the 5th scene with the sphere with basic volumetric material around the whole cave. It was too pale so I restored the shadows strength and saturation to the levels I wanted.
Click thumbnail to see full-size image