Luminance

Synopsis

The luminance macro performs full-colour luminance filtering and produces a 1:1 size scalar result from ARGB colour byte images.

Input Ports

Name	Type	Description

in	Image_ARGB	original image to be analysed

Output Ports

Name	Type	Description

out_fld	2D byte field	luminance values for each pixel
out_obj	GDobject	directly renderable output object

Description

The luminance module computes a scalar luminance function for each pixel in an image from the red, green and blue channels of that color image. The output field is the same size of the input in each dimension. There are no parameters associated with this module, and hence no user interface.

The transfer function used to calculate the luminance is:

Luminance = (RED*0.299) + (GREEN*0.587) + (BLUE*0.114)

This module is a conversion of the AVS5 "luminance" module. The module implementation is now in C++. The low-level module operates on simple byte arrays rather than fields.

Inputs

Full colour 2D image that is to be analysed by the module. The image should be a 2D uniform grid of type Image_ARGB. The read_image module outputs data of this type.

Outputs

out_fld

Uniform scalar byte field containing the calculated luminance values as unsigned bytes. The uniform field has the same dimensions as the input field.

out_obj

The GDobject version of the output, suitable for direct connection to the viewer. A 2D viewer is recommended.

Utility Macros

The luminance macro makes use of the LuminanceCore low-level module.

Example

The LuminanceEg example application filters an image and shows it in a viewer.

Files

iac_proj/lumi/lumimods.v contains the V definition of the LuminanceCore module.

iac_proj/lumi/lumimacs.v contains the V definitions of the luminance user macro and the LuminanceEg example application.

Other Notes

The low-level LuminanceMods library containing the low-level LuminanceCore module does not specify a process. By default the express process will be used.

Authors

Sabreen Vig, Larry Gelberg, Ian Curington
Advanced Visual Systems, Inc.

Modifications

Andrew Dodd
International AVS Centre

Contact

International AVS Centre
Manchester Visualization Centre
Manchester Computing
University of Manchester
Oxford Road
Manchester
United Kingdom
M13 9PL