Logo Extractor plugin

Plugin BPP_LogoExtractor is intended to extract and save of static elements of TV picture, for example channel's logo. The extracted images may further be used in plugin BPP_LogoDetector.

The extraction of logo is performed by filling by selected color the part of image that belongs or, vice versa, doesn't belong to the required logo, you may further set that color as transparent on showing extracted logo on screen.

For extracting the logo you need to open the dialog window of plugin settings. There will appear a gray frame on the screen, you need to match the size and position of that frame with logo on the screen and press «Start» after that. The parts of picture inside the frame that don't belong to the logo will automatically be filled with selected key (transparent) color. If you are not satisfied with the result of plugin work, the contents of selected zone may be cleared and you may start exposition process again. Saving of the result will be available after the exposition will stop work.

The principle of extracting logo is based on that the range of changing the brightness on the logo never exceeds some definite value that depends only on transparency of logo and on the level of noise in the picture. This value is set in plugin settings in the «Threshold» box. If the range of brightness of some pixel on the screen will exceed this value, then the pixel will be filled with selected transparency coloer. For fully opaque logos this value is only defined by the level of noise in the picture.

The amount of exposition time depends on the intensity of changing the brightness in selected zone and on threshold set. The less the logo transparent, the less you may set the threshold, and correspondingly the less you need to wait while the brightness changing in the vicinity of logo will exceed the set threshold.

The minimal and sufficient requirement for normal extraction is the dynamics of changes in the picture near the logo. Nevertheless sometimes appears the situation when the logo is placed over the completely static background, for examples on the margins of widescreen movie. In this case the only possible method of extraction logo os comparing it's brightness with black level. The setting «Black level» provides such possibility to force fill by transparency color of all elements whose brightness is below the given value.

The size and position of logo is set in percents of screen size, so they don't depend on video stream parameters. The logo is saved in BMP format. the size of saved bitmap is brought to the size relative to the maximal size of video stream – 768*576 (square pixel).

List of changes

• First release.

• Added saving of settings under Windows 7.

• Added support of Behold TV instances.

Link to the plugin: BPP_LogoExtractor_v102.zip (23.1 kb)

01.03.11