The IlvComponentTransferFilter Class

Image Processing Filters > IlvBitmapFilter: The Image Processing Class > The IlvComponentTransferFilter Class

The IlvComponentTransferFilter class lets you perform component-wise remapping on images as follows:

R' = feFuncR( R )

G' = feFuncG( G )

B' = feFuncB( B )

A' = feFuncA( A )

feFuncR, feFuncG, feFuncB, and feFuncA define the transfer functions for each component.

It allows operations such as brightness adjustment, contrast adjustment, color balance, or thresholding.

Five predefined transfer functions are defined:

identity: C' = C

table: the function is defined by linear interpolation into a lookup table by attribute values, which provides a list of n+1 values (that is, v0 to vn) in order to identify n interpolation ranges. Interpolations use the following formula:

k/N <= C < (k+1)/N => C' = vk + (C - k/N)*N * (vk+1 - vk)

discrete: the function is defined by the step function defined by attribute values, which provides a list of n values (that is, v0 to vn-1) in order to identify a step function consisting of n steps. The step function is defined by the following formula:

k/N <= C < (k+1)/N => C' = vk

linear: the function is defined by the following linear equation:

C' = slope * C + intercept

where slope and intercept are user specified.

gamma: the function is defined by the following exponential function:

C' = amplitude * pow(C, exponent) + offset

where amplitude, exponent, and offset are user specified.

Transfer functions are classes on their own and can be redefined (see IlvTransferFunction, IlvIdentityTransfer, IlvLinearTransfer, IlvTableTransfer, IlvDiscreteTransfer, and IlvGammaTransfer).

Version 5.5.1