TANDBERG EN8000, Справочное руководство

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Creating and Downloading a Logo
Reference Guide: EN8000 MPEG-4 Part 10 (H.264/AVC) Encoders Page D-7
ST.RE.E10233.1
Osd Creator uses a colour palette with a maximum of 256 entries. Each pixel in the image is
mapped to an entry in the palette, which holds a value for the red, green and blue and
transparency component. The transparency (or
mix ) is treated as a colour component, so for
two colours with identical red, green and blue values, but different transparency levels, two
entries will be generated in the palette.
When a bitmap image is loaded, all colours have a transparency value of 255 (opaque).
The area of the image that is to remain opaque is referred to as the active area . The area of
the image that is to be made transparent is called the inactive area . Transparency can added
manually, with a brush, or by using a key file .
Adding Transparency Manually
The background colour within Osd Creator can be changed with the black, red, green and
blue buttons on the toolbar. This changes the background colour of the editor window on
which the logo is overlaid and not the logo itself, which remains unaffected. This facility is
useful to show the transparency of different colours. It is best to start with a background colour
that contrasts sharply with the whole of the source image.
Using the options immediately below the toolbar, the mouse pointer can be used as a brush to
add transparency to an area. The left mouse button will apply the transparency value set for
the
LButtonMix and the right mouse button will apply the transparency value set for the
RbuttonMix . At start-up these are set so LButtonMix is 0, to make an area transparent, and
RButtonMix is 255, to make it opaque.
Different mix levels can be entered for intermediate levels of transparency. Selecting a brush
size from the drop-down list determines the size of the area that is changed.
If the Changes Affect Palette box is checked, changing the transparency of a pixel on the
image also changes the palette entry on which the pixel is based, and all the pixels that share
that palette entry.
If the inactive area is mainly one colour, check the Changes Affect Palette box, and left-click
in the inactive area. All pixels of that colour should become background-coloured. Repeat until
the whole of the inactive area is transparent. If parts of the active area have become
transparent, uncheck the
Changes Affect Palette box, and paint with the right button to
correct these areas. Zoom in if necessary.
If there is no general colour for the inactive area, uncheck the Changes Affect Palette box
and paint the inactive area manually with the left mouse button. Use the right button to correct
mistakes. Trace around the edge of the area with a medium brush, then use the large brush
for wide areas. Zoom in to do the fine corrections.
Adding Transparency Using a Key File
A key file is a Bitmap (.bmp) file of the same size as the source file, with the active area of the
image coloured white, the inactive area coloured black, and intermediate levels of
transparency coloured grey.
Create the key file using a drawing package. Colour the active area white, and the inactive
area black. Save as a .bmp file.
Click the Key File toolbar button. Select the key file . The inactive area of the image should
now be transparent (background-coloured). Change the background colour to verify that the
correct area is transparent.