the beginners explanation of gamma correction and linear workflow

8/2/2019 The Beginners Explanation of Gamma Correction and Linear Workflow

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What is Gamma?Its all to do with how devices display images


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What is Gamma?

Input: Voltage

To display images on screen an input voltage is applied


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What is Gamma?

Input: Voltage

Output: Light Intensity

Which outputs as light intensity on the screen


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What is Gamma?

Input: Voltage


Input Signal

Light Intensity

In a perfect world, the input would equal the output linearly


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What is Gamma?

Input: Voltage


Input Signal

Light Intensity

But it actually looks something like this (a powerlaw function)


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What is Gamma?

Input: Voltage


Input Signal

Light Intensity

Compensation is added to make it linear again


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What is Gamma?

Input: Voltage


Gamma

The numerical value of this exponent is given the name Gamma

Input Signal

Light Intensity


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What is Gamma?How does this aect 3D applications?


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What is Gamma?Floating point render engines like LightWave and modo work in linear space internally


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What is Gamma?

TIF

TGA

JPG

Gamma Applied

But texture images and colour pickers already have gamma applied so they can be seen properly on screen

This doesnt apply to HDR image formats, as they are in linear spaceSome colour pickers can remove gamma from picked colours (e.g. Jovian for LightWave)*

*

Linear Internally


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What is Gamma?

TIF

TGA

JPG

Gamma Applied

Render

Mixed Gamma

Sa

Double Ga

+

If you dont de-gamma textures and colours, but apply gamma on the nal image,

you double the gamma on the textures and colours that already had it, making them look washed out

Linear Internally


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What is Gamma?

De-Gamma (1.0 / Target Gamma)

TGA

JPG

TIF

The trick is to de-gamma the images and picked colours

Linear Internally


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What is Gamma?


TGA

JPG

TIF

Render

Linear Workow

This is so everything remains in linear space throughout, this is called Linear Workow

Linear Internally


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What is Gamma?


TGA

JPG

TIF

Render

Linear Workow

Sa

Apply Ga

But you must apply your target gamma at the end so it displays it correctly on screen

Linear Internally


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What is Gamma?


TGA

JPG

TIF

Render

Linear Workow

H

Tonemap I

But you must apply your target gamma at the end so it displays it correctly on screen

Linear Internally


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Gamma Corrected


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the beginners explanation of gamma correction and linear workflow

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