Isys
®
12” Tilt Touch Screen
Crestron
TPMC-12
shareware. The TPMC-12 touch screens only accept the following WAV file format:
PCM, 8 and 16 bit, 8 – 44.1kHz, mono and stereo
. For more information about
how to use Sound Recorder, refer to its User’s Guide and extensive help information
provided with the software. Also refer to the help file in VT Pro-e to learn how to
use its audio tool, Sound Manager, to attach WAV files to a touch screen project.
Pre-recorded WAV files for voice prompts and responses are available from
Crestron. These files can be stored into and programmed for use in the touch screen
directly or may be edited with the Sound Recorder. For example, the individual files
can be combined to create custom messages.
NOTE:
Touch screen WAV files can be obtained from the Wave LC Library of the
Crestron FTP site.
Bit Depth and File Size
A balance of performance and quality can be achieved by using VT Pro-e to
configure the size of graphics in a project. Read this section to learn about bit depth
and how to maximize the quality and performance of a TPMC-12 project.
Bit depth refers to the number of memory bits used to store color data for each pixel
in a raster image. A touch screen raster image consists of a rectangular grid of
picture elements (pixels). Each pixel uses the same amount of memory to store its
color data. The amount of memory is called the bit depth of the image.
Greater bit depths are required to represent finer gradations of color. Increasing bit
depth necessarily increases file size. A black and white drawing requires only one bit
per pixel to store all the available color information. Using a 32-bit per pixel bit
depth for a black and white image increases the file size 32 times without adding
anything to the black and white image quality.
In an 8-bit per pixel system, the associated 8-bits of video memory for every screen
pixel contain a value referring to a location in an 8-bit color table. In this way any
one of the specific 256 color table locations is assigned to a pixel.
A 16-bit highcolor system is considered sufficient to provide life-like colors. It is
encoded using 5-bits to represent red, 5-bits to represent blue and (since the human
eye is more sensitive to the color green) 6-bits to represent 64 levels of green. These
can therefore be combined to provide 65,536 mixed colors (32 x 32 x 64 = 65,536).
In a 24-bit graphics display, the video memory allocates 24 bits for each pixel on the
screen enabling each pixel to take on any one of a possible 16.7 million colors. Each
24-bit value is composed of 8-bits for red, 8-bits for green and 8-bits for blue. These
triplets of 8-bit values are also referred to as the red, green and blue color planes. A
24-bit image is actually composed of three component images which combine to
create the truecolor picture. The reason this is called truecolor is that this is near the
maximum number of colors the human eye is able to detect.
Truecolor images are sometimes represented by a 32-bit value. The extra 8-bits do
not enhance the precision of the color representation but act as an alpha channel that
represents pixel translucence. The 32-bit truecolor has become popular on the
computer desktop to provide effects such as translucent windows, fading menus and
shadows.
In graphics intensive applications such as touch screens, raising or lowering the color
depth of the displayed graphics can achieve a balance of performance and quality.
Lower color depths do not require as much frame buffer memory or display
bandwidth, allowing them to be generated and displayed more quickly. Increasing
color depth results in higher color quality at the expense of display speed and
responsiveness. By using mostly 8-bit or 16-bit graphics and holding 32-bit graphics
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Isys
®
12” Tilt Touch Screen: TPMC-12
Operations Guide – DOC. 6675C
