control issues in version 0.9 about delaboratory HOT 4 CLOSED

Well there are too many issues in one issue to follow.

About the first one - primary feature of delaboratory is to work in multiple 
colorspaces. What you expect is to use RGB colorspace but create curve from 
other colorspace - why? If you want to play with luminance you can try L from 
LAB or L or HSL, there is also K in CMYK. Using combined RGB curve is always 
worse choice.

The basic layer need improvements, I know, this is just a start.

Please also note that there is no 0.9 version, then last one is 0.6.9.1.

"What you expect is to use RGB colorspace but create curve from other 
colorspace - why? If you want to play with luminance you can try L from LAB or 
L or HSL, there is also K in CMYK. Using combined RGB curve is always worse 
choice."

Adjusting curve (gamma) in all channels at once in RGB space is very common 
used transform for enchancing images. It even described in 'creative shooting 
tips for dummies' in the shooting manuals for adjusting video camera's DSP:
1. All levels 'standard' gamma-curve correction - 
http://pro.sony.com/bbsccms/assets/files/micro/xdcamex/solutions/Create_Film-lik
e_Images.pdf
2. Low/Black range levels partial gamma-like correction - 
http://pro.sony.com/bbsccms/assets/files/micro/xdcamex/solutions/Enrich_Color_Sa
turturation.pdf
As I assume both of these corrections are performed in per-channel basis in RGB 
color space (before Y,R-Y,B-Y matrix), because there is a special Y-based gamma 
adjustment (L in HSL space) - 
http://pro.sony.com/bbsccms/assets/files/micro/xdcamex/solutions/Shooting_Pictur
es_w_Black_Colors.pdf . Also as you see in the scheme at the end of this 
document 'gamma and black gamma' sircuits are in RGB channels before Y,R-Y,B-Y 
matrixing.

When we adjust curve/gamma for all 3 RGB channels at once we not only affects 
luminannce (absolute RGB levels), but also change relative proportion between 
RGBs that cause saturation changes. That is not only 'L' correction in HSL or 
'K' in CMYK. But it is simple and useful correction for real images for 
enchancing saturation of colors and increasing contrast where we need.

"Please also note that there is no 0.9 version, then last one is 0.6.9.1."

Oh - I too bad in remembering numbers. Yes - current comments are for version 
0.6.9.1.

This feature request is quite popular so I will probably create separate layer 
type for combined RGB curve manipulation in the future.

levels have been implemented