Module prisma::ycbcr

A module for encoded values in the YUV and YIQ family of device-dependent color models.

YUV and YIQ refer to a collection of spaces, each derived from a parent RGB space. Fundamentally, these spaces are created from a linear transformation from a parent RGB space. There are standard definitions for both the conversion matrices as well as the RGB space to use as the parent, but many other YUV-like spaces can be constructed.

Traditionally, the term YCbCr refers to a integral encoded digital signal within the YUV space and the term YPbPr refers to a normalized floating point digital signal. However, for the purposes of this library, YCbCr refers to both the integral and floating point representations of these colors.

Both YUV and YIQ are represented by a luminosity (Y) or, more commonly, a luma (Y'), channel and two opponent chromaticity channels. Both of the chromaticity channels center at zero (for achromatic colors) and run both positive and negative.

The exact canonical range for the channels varies between spaces, so we opt to normalize all chromaticity channels to a fixed [-1.0, 1.0] range for float channels. Integral channels run from 0 to PrimInt::max_value() with the central value (PrimInt::max_value() >> 1) + 1 representing a neutral value.

YIQ is a nearly obsolete space used for NTSC televisions. It is equivalent to a 33 degree rotation from the standard YUV plane and thus can represent the same set of colors. It is represented in this library by the type type Yiq<T> = YCbCr<T, YiqModel>, but provides some convenience methods to mask the fact that it shares an implementation with YCbCr.

Structs

BareYCbCr	A YCbCr color that does not know its model.
Bt709Model	A model for YUV using the BT.709 standard.
CustomYCbCrModel	A model with transformations that are defined at runtime.
JpegModel	A model for YUV used by Jpeg images.
StandardShift	The standard shift, filling the full range of all channel types.
YCbCr	A color in the YCbCr family of color spaces.
YiqModel	A model for the YIQ color space.

Enums

YCbCrOutOfGamutMode

Methods for handling out of gamut colors when converting to Rgb.

Traits

Canonicalize	A YCbCrModel that can transform a color in its space to the "canonical representation".
UnitModel	A YCbCrModel that stores no data and thus can be used without an object.
YCbCrModel	An object that can transform from YCbCr to Rgb and back.
YCbCrShift	A coordinate shift for the components of a YCbCr model.
YCbCrTransform	A model with matrix transformations.

Functions

build_transform

Build a transformation matrix for conversion from Rgb to a YCbCr space with a specified set of weight values.

Type Definitions

YCbCrBt709	A YCbCr color with a Bt709Model.
YCbCrCustom	A YCbCr color with a reference to a CustomYCbCrModel.
YCbCrJpeg	A YCbCr color with a JpegModel.
Yiq	A YCbCr color with a YiqModel.