GY-63_MS5611/libraries/GAMMA

GAMMA

Arduino Library for the GAMMA function to adjust brightness of LED's etc.

Description

This library is provides a gamma lookup class. It is typical used to change the intensity / brightness of a LED to match the human eye. When a LED is given 50% PWM it looks far brighter for the eye.

This lib provides a balance between an expensive math function and the speed of a lookup table.

The accuracy of the library depends on the size of the internal array. A size of 256 is the reference. Smaller arrays use interpolation and these interpolated values are good (< 1%) down to internal array size 16. The size can be as small as 2 which is pretty inaccurate. In this latter case the curve is approximated by only two linear interpolations. In short, choose the size that fits your application.

The library has a setGamma() function that allows an application to change the gamma value runtime. This allows adjustments that a fixed table does not have.

The class can be used to dump the internal table e.g. to place in PROGMEM.

Interface

Core functions

• GAMMA(size = 32) constructor, gets the size of the internal array as parameter. The array is initialized with a gamma == 2.8 which is an often used value.
  The default for size = 32 as this is a good balance between performance and size ot the internal array. The size parameter must be in {2, 4, 8, 16, 32, 64, 128, 256 }
• setGamma(float gamma) calculates and fills the array with new values. This can be done runtime so runtime adjustment of gamma mapping.
  This function relative quite some time.
• getGamma() returns the set gamma value.
• operator [] allows the GAMMA object to be accessed as an array. like x = G[40]; Makes it easy to switch with a real array.

Development functions

• size() returns size of the internal array.
• distinct() returns the number of distinct values in the table.
• dump() dumps the internal table to Serial. Can be useful to create a direct usable array in RAM, PROGMEM or wherever.

Future ideas

• look for optimizations
• uint16 version?

Operation

See example