Colour mapping in post

[3LP]

Bringing this back from the dead. Could anybody explain how to achieve this in AE or Photoshop please without plugins. Is it possible without plugins? If I look at my "curves" of my 32 bit image (or any image for that matter) in photoshop, it starts of with just a straight line going from bottom left to upper right. (even if it is gamma 2.2). So I have no idea how am I supose to display the curves as you show here in the attached sample

Hey there,

Is there a way of having this same (or more detailed) curve for the HSV Exponential?
I don't know the mathematical algorithm that sits behind, but it would be great to be able to create that color mapping in post...

Whatever I try, going from linear and comping, I'm always ending with a washed out image like the Reinhard curve (render or post)
But I would like to keep the vivid of the render, HSV Expo does that, and it would be great what exactly it does to be able to reproduce this in comp. (we need to go out in linear for the comping)

Thanks

Stan

[vlado]

Which program are you using for compositing? The HSV exponential mapping cannot be represented by RGB curves only, the maths is more complicated...

Best regards,
Vlado

[3LP]

Afx, I know it's not as powerful as nuke or other real comp progs, but I was hoping to be able to get away with some curves. Because AFX curves are crap, i'm using FL Curves from Frischluft.

http://www.frischluft.com/curves/index.php

If it's not powerful enough, is there any other way of doing it in afx?

I'm already quite close to the Reinhard with this, but I'm playing only with RGB, maybe the other options could help for this matter?


Maybe a script expression involving those channels ?

Thanks Vlado!

Stan

[vlado]

Hm, adjusting the brightness curve in the same shape should give you what you want.

Best regards,
Vlado

[3LP]

Nice! It seems to be a lot close indeed, and it preserve the color!
Is there any way of expression scripting this curve, either the reinhard or the HSV Expo?

Thanks again,

Stan

[vlado]

The exact formula for the Reinhard mapping is this:

new_bright=brightness*multiplier;
new_bright=new_bright*(1+new_bright*(burnValue*burnValue))/(1+new_bright);

The exact formula for the exponential mapping is this:

k=darkMult*(1.0f-brightness)+brightMult*brightness;
new_bright=1.0f-expf(-brightness*k);

Best regards,
Vlado

[henning]

Thanks for the formulas, Vlado.
In case anyone wants to try these out in Fusion:

Reinhard:

[SIZE=1]
{
	Tools = ordered() {
		ct_Reinhard = Custom {
			CtrlWZoom = false,
			NameSet = true,
			Inputs = {
				NumberIn1 = Input { Value = 1, },
				NumberIn2 = Input { Value = 0.5, },
				RedExpression = Input { Value = "c1 * (1 + (c1 * n1) * (n2^2)) / (1 + (c1 * n1))", },
				GreenExpression = Input { Value = "c1 * (1 + (c1 * n1) * (n2^2)) / (1 + (c1 * n1))", },
				BlueExpression = Input { Value = "c1 * (1 + (c1 * n1) * (n2^2)) / (1 + (c1 * n1))", },
				NumberControls = Input { Value = 1, },
				NameforNumber1 = Input { Value = "Multiplier", },
				NameforNumber2 = Input { Value = "Burn Value", },
				ShowNumber3 = Input { Value = 0, },
				ShowNumber4 = Input { Value = 0, },
				ShowNumber5 = Input { Value = 0, },
				ShowNumber6 = Input { Value = 0, },
				ShowNumber7 = Input { Value = 0, },
				ShowNumber8 = Input { Value = 0, },
				PointControls = Input { Value = 1, },
				ShowPoint1 = Input { Value = 0, },
				ShowPoint2 = Input { Value = 0, },
				ShowPoint3 = Input { Value = 0, },
				ShowPoint4 = Input { Value = 0, },
				LUTControls = Input { Value = 1, },
				ShowLUT1 = Input { Value = 0, },
				ShowLUT2 = Input { Value = 0, },
				ShowLUT3 = Input { Value = 0, },
				ShowLUT4 = Input { Value = 0, },
			},
			ViewInfo = OperatorInfo { Pos = { 1595, 7375.5, }, },
		},
	},
	ActiveTool = "ct_Reinhard",
}
[/SIZE]

Exponential:

[SIZE=1]
{
	Tools = ordered() {
		ct_exponential = Custom {
			CtrlWZoom = false,
			NameSet = true,
			Inputs = {
				NumberIn1 = Input { Value = 1, },
				NumberIn2 = Input { Value = 0.9206349, },
				RedExpression = Input { Value = "1 - e ^ (-c1 * (n1 * (1-c1) + n2 * c1))", },
				GreenExpression = Input { Value = "1 - e ^ (-c1 * (n1 * (1-c1) + n2 * c1))", },
				BlueExpression = Input { Value = "1 - e ^ (-c1 * (n1 * (1-c1) + n2 * c1))", },
				NumberControls = Input { Value = 1, },
				NameforNumber1 = Input { Value = "dark Multiplier", },
				NameforNumber2 = Input { Value = "bright Multiplier", },
				ShowNumber3 = Input { Value = 0, },
				ShowNumber4 = Input { Value = 0, },
				ShowNumber5 = Input { Value = 0, },
				ShowNumber6 = Input { Value = 0, },
				ShowNumber7 = Input { Value = 0, },
				ShowNumber8 = Input { Value = 0, },
				PointControls = Input { Value = 1, },
				ShowPoint1 = Input { Value = 0, },
				ShowPoint2 = Input { Value = 0, },
				ShowPoint3 = Input { Value = 0, },
				ShowPoint4 = Input { Value = 0, },
				LUTControls = Input { Value = 1, },
				ShowLUT1 = Input { Value = 0, },
				ShowLUT2 = Input { Value = 0, },
				ShowLUT3 = Input { Value = 0, },
				ShowLUT4 = Input { Value = 0, },
			},
			ViewInfo = OperatorInfo { Pos = { 1595, 7441.5, }, },
		},
	},
	ActiveTool = "ct_exponential",
}
[/SIZE]

Just copy the text and paste in the Fusion flow view.
If you spot errors in my translated formular please tell me.

[3LP]

Awesome, This is great, Thanks henning and Vlado.

Would be even better if someone could find a way to code this in AFX, I guess it's possible with the FL Curves from Frischluft, but I'm still trying to find how to expression them

Any other way would be great as well.

Stan

[henning]

Well I started to download Visual Studio Express, the SDK and all that but haven't had time to do anything other than trying to compile the example plugins from afx.
But just doing a simple plugin with a fixed formula and two sliders should be simple, right?