Follow Techotopia on Twitter

On-line Guides
All Guides
eBook Store
iOS / Android
Linux for Beginners
Office Productivity
Linux Installation
Linux Security
Linux Utilities
Linux Virtualization
Linux Kernel
System/Network Admin
Programming
Scripting Languages
Development Tools
Web Development
GUI Toolkits/Desktop
Databases
Mail Systems
openSolaris
Eclipse Documentation
Techotopia.com
Virtuatopia.com

How To Guides
Virtualization
General System Admin
Linux Security
Linux Filesystems
Web Servers
Graphics & Desktop
PC Hardware
Windows
Problem Solutions

  




 

 

3.20.  Semi-Flatten

Revision History
Revision $Revision: 1.22 $ 2006-11-12 j.h

3.20.1.  Overview

You can find this filter through Filters->Colors->Semi-Flatten It is available if your image holds an Alpha channel (<Image>Layers/Transparency/Add an alpha channel). Otherwise, it is greyed out.

The Semi-flatten filter helps those in need of a solution to anti-aliasing indexed images with transparency. The GIF indexed format supports complete transparency (0 or 255 alpha value), but not semi-transparency (1 - 254): semi-transparent pixels will be transformed to no transparency or complete transparency, ruining anti-aliasing you applied to the logo you want to put onto your Web page.

Before applying the filter, it's essential that you should know the background color of your Web page. Use the color-picker to determine the exact color which pops up as the Foreground color of the Toolbox. Invert FG/BG colors so that BG color is the same as Web background color.

Semi-flatten process will combine FG color to layer (logo) color, proportionally to corresponding alpha values, and will rebuild correct anti-aliasing. Completely transparent pixels will not take the color. Very transparent pixels will take a few color and weakly transparent will take much color.

3.20.2.  Example

Figure 11.61.  Toolbox Background color (pink) and an image with feathered edges on a transparent background, at a 800% zoom level.

Toolbox Background color (pink) and an image with feathered edges on a transparent background, at a 800% zoom level.
Toolbox Background color (pink) and an image with feathered edges on a transparent background, at a 800% zoom level.

Figure 11.62.  Result, in GIF format, after applying Semi-flatten filter.

Result, in GIF format, after applying Semi-flatten filter.

Full transparency is kept. Semi-tranparent pixels are colored with pink according to their transparency (Alpha value). This image will well merge into the pink background of the Wew page.


 
 
  Published under the terms of the GNU General Public License Design by Interspire