New plugin LabTools 0.6

[roland65]

Update 16/08/2012 - Renamed to LabTools
Update 25/06/2012 - Added new saturation control. It allows to increase / decrease image saturation by modifying the Lab a and b channels. Released new version 0.5.
Update 21/06/2012 - Fixed the version ID in the XML file and improved speed of the RGB <-> LAB conversion. Released new version 0.4.
Update 20/03/2012 - Fixed a bug that caused color artefacts. Released new version 0.3.
Update : I released today a new version (0.2) which works with the Lab L channel and so has much less color casts.
RB

Hi,

I released today a new free plugin called SContrast. This is an implementation of the standard S curve for contrast increase or decrease. There are two parameters to adjust your image: contrast and lightness.

If you want to move this plugin within the tabs, its customToolsUI.txt keyword is : com.roland65.LabTools

Download the plugin here : http://www.aftershotpro.com/plugins/ind ... g=labtools
Have a nice day,
RB

[nyukuri]

Hi Roland,
Is this the same S-contrast as offered in Bez plugin?

[roland65]

I think it uses the same theoretical basis, but the implementation is different. For example, SContrast works on the Lab L channel and uses fast math routines.
RB

[nyukuri]

ok, thank you

[ferdinand-paris]

Bez for ASP also works on a luminosity channel, although it is L in either HCL or HSL, rather than running in the LAB stage in the processing pipe.

Sig contrast in Bez uses the sigmoidal formula, which necessitates using Exp and Ln functions, although on my main PC I don't really detect any processing lags. My netbook is a different matter, but then a lot of things are slow on it.

F_P

[gareth]

On my ORF files, enabling this plugin - even with setting 0,0 - adds lots of brightly coloured noise to the image.
Very pretty but not what I want to achieve

[roland65]

Congratulations, you've found a bug
I fixed it and uploaded a new version of the plugin (version 0.3) to the Corel plugin site (http://www.aftershotpro.com/plugins/?plug=scontrast)
Could you test it?
Thanks,
RB

[WilsonC]

Dang, you are fast! When I went to install 0.3 Aftershot still believes it is 0.2....so it asks if it should replace 0.2 instead of upgrade it.

[gareth]

That's fixed it ... no more speckles and the colour stability looks pretty good ( to me - though I am not a pro )
The Help shows 0.3 but your install file needs fixing to be 0.3.

Thanks

I have been using my own sigma curves but I really miss the 'use Lab Curves' B5 plugin
( any chance of an ASP 'use lab curves' as you are working in that area - I used to like that for solarisation effects ! )

[roland65]

Dang, you are fast! When I went to install 0.3 Aftershot still believes it is 0.2....so it asks if it should replace 0.2 instead of upgrade it.

Probably I was too fast because I forgot to update the version ID in the XML file.
Anyway, in between I released a new version (0.4) with this glitch fixed and also some improvement in the RGB <-> LAB conversion speed.
This one should stay for a while...
RB

[roland65]

I have been using my own sigma curves but I really miss the 'use Lab Curves' B5 plugin
( any chance of an ASP 'use lab curves' as you are working in that area - I used to like that for solarisation effects ! )

I remember there was a LabCurves plugin from Thomas Baruchel, but I don't know what it was supposed to do. Could you give me some explanations about it?
RB

[afx]

I remember there was a LabCurves plugin from Thomas Baruchel, but I don't know what it was supposed to do. Could you give me some explanations about it?
RB

Source can be found here:
http://afximages.com/stuff/plugins/Baru ... ources.tgz

cheers
afx

[roland65]

Source can be found here:
http://afximages.com/stuff/plugins/Baru ... ources.tgz

Yes, I have these sources and I have looked to the code. Here is what I understand.

There are two functions and one parameter called amp.

The first function converts RGB -> Lab and then applied these formulas:
R=65535*L/100
G=65335/(2*amp)*(a+amp)
B=65535/(2*amp)*(b+amp)

The other function applies these formulas :
L= R/65535*100
a=G/65535*(2*amp)-amp
b=B/65535*(2*amp)-amp

and then converts Lab -> RGB

It is not clear to me where exactly in the pipe these function are called, but I'm sure the first one is called before the second one. I don't know what processing is supposed to be done between the two.

If I understand well, the amp parameter shifts the a and b channels, but after that they get the same value as before? If someone understands what is done here...
RB

[gareth]

I shall describe from a user perspective ( ie ignorance )

The effect is that when enabled, the red channel on the Curves window represents L and dragging points on the red curve results in a suitable change to the value of L
I have used it with a red sigmoid curve for contrast effects and an M or W shape to introduce a solarisation look alike.
The other two channels are more difficult to drag on the screen but do indeed affect a and b.

I guess the two formulae convert from the current state to screen display coordinates ( which then represents Lab ) [ then the in-out mapping from the screen is applied here ] and back again to reflect changes to the red line back into a change to actual values. So they should, I think wrap the place where Curves are applied to the image.

[roland65]

OK, I understand now how it works. However, I'm not sure about the purpose of the amp (amplitude) parameter. I think it controls the amount of the curve effects that are applied, am I correct? Do you think this parameter is important?
RB