iSignager 500A
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A.3.4 PNG
PNG (Portable Network Graphics) is a lossless compressed bitmap image format. PNG
was created to both improve upon and replace the GIF format with an image file format not
requiring a patent license to use. PNG is officially pronounced "ping" and, like GIF and
BMP, reduces file size by reducing the number of colors. PNG can also be 24-bit
true-color and maintain all the original image information, but file sizes are large.
A.4 Standard Definition (SD) Introduction
A.4.1 SDTV
Standard-definition television or SDTV refers to television systems that have a lower
resolution than HDTV systems. The term is usually used in reference to digital television,
in particular when broadcasting at the same (or similar) resolution as analog systems.
In ATSC, SDTV can be broadcast in 704 pixels × 480 lines with 16:9 aspect ratio (40:33
rectangular pixel), 704 pixels × 480 lines with 4:3 aspect ratio (10:11 rectangular pixel) or
640 pixels × 480 lines with 4:3 ratio (and square pixels). The refresh rate can be any of
24, 30 or 60 pictures per second.
Digital SDTV in 4:3 aspect ratio has the same appearance as the regular analogue TV
(NTSC, PAL, PAL2, SÉCAM) minus the ghosting, snowy images and static noises.
However, if the reception is poor, the user may encounter various other artifacts such as
blockiness and stuttering.
Standards that can broadcast digital SDTV include DVB, ATSC and ISDB. The latter two
were originally developed for HDTV, but they have proved to be more often used for their
ability to deliver multiple SD video and audio streams via multiplexing, than to use the
entire bitstream for one HD channel.
A.5 High Definition (HD) Introduction
High-definition video or HDTV generally refers to any video system of higher resolution
than standard-definition (SD), i.e. NTSC, SÉCAM and PAL. HDTV is broadcast digitally,
Summary of Contents for iSignager 500A
Page 1: ...iSignager 500A Page i iSignager 500A User Manual ...
Page 2: ...iSignager 500A Page ii Revision Date Version Changes 2008 04 1 0 Initial Release ...
Page 10: ......
Page 11: ...iSignager 500A Page 1 1 Introduction Chapter 1 ...
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Page 21: ...iSignager 500A Page 11 2 Installation Chapter 2 ...
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Page 37: ...iSignager 500A Page 27 A Video Audio and Graphic Formats Appendix A ...
Page 45: ...iSignager 500A Page 35 B Check and Modify the Player Status by Serial Port Appendix B ...
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Page 59: ...iSignager 500A Page 49 C Hazardous Materials Disclosure Appendix C ...
