Chroma Transform

Selectively renders a specified color as transparent for the specified image.

Note To use this transform, you need to have Microsoft® Internet Explorer 5, Microsoft Windows® 98 Second Edition, or Windows 2000 installed.

Transform Specifications

The following table contains the information you need in order to use this transform in C++ and script.

Class identifier (CLSID)	CLSID_Chroma
Globally unique identifier (GUID)	421516C1-3CF8-11D2-952A-00C04FA34F05
Programmatic identifier (ProgId)	DXImageTransform.Microsoft.Chroma
Category identifier (CATID)	CATID_DXImageTransform
Custom interfaces	IChroma
Supported interfaces	None
Inputs	One required of type IDXSurface.
Output	IDXSurface

Custom Properties

The following table lists the custom properties that control the transform output.

Property Name	Type	Default	Description
Color	long	0xFF0000FF	The hexadecimal value of the color to be treated as transparent. This color is expressed in 0xAARRGGBB format, where AA is the alpha hexadecimal value, RR is the red hexadecimal value, GG is the green hexadecimal value, and BB is the blue hexadecimal value.

Remarks

This effect is not recommended for files that have been dithered from 24-bit to 8-bit color. In particular, JPEG files, which are both dithered and compressed, do not produce entirely solid transparent regions. The chroma transform also is not recommended for anti-aliased sources, in which jagged lines are smoothed by blending the lines with the colors of the surrounding pixels. Choosing a specific chroma color will cause some colors that would otherwise be transparent to be fully opaque.