PAL (display format)
PAL stands for phase Alternating LINE and is a procedure for the ink transfer with the similar television. Here there are many subspecies, which mark itself with respect to some technical data to differentiate and by an auxiliary letter. In Germany for example PAL B/G is used.
A substantial distinction lies in the image repetition frequency, which is derived from the frequency. There are two variants. PAL-50 for 50 cycles per second and PAL-60 for 60 cycles per second. With PAL-50 usually 625 lines will transfer, by which however only 576 lines are visible. With PAL-60 usually 525 lines will transfer, by which 480 is visible.
Beside these technical Defininition PAL is used however also colloquially as name for the display format. That is not correct and leads to confusion, was however in such a way established.
PAL is in connection with DVDs and other digital videos a recapitulatory name for display formats with 576 lines. The horizontal dissolution varies. Alternatively also 576i stands and/or on use of the interlaced scanning. 576i50 (half-image rate: 50 cycles per second), with frames also 576p and/or. 576p25 (frame rate: 25 cycles per second).
Table of contents
|dissolution (lines)||equivalents dissolution (dpi) to a viewing distance of 25 cm||viewing distance (m)||distance/diagonal|
|16:9 (70 cm × 39 cm)|
|PAL 16:9 TV||540||,280 - 336||2 - 2.40||2.5 - 3|
|hp 720||,720||,280 - 336||1.50 - 1.80||1.85 - 2.25|
|hp 1080||1080||280 - 336||1 - 1.20||1.25 - 1.5|
dpi the data for the dissolution seen from the indicated viewing distances is equivalent to the dissolution of pictures computed, out 25 cm distance to be regarded.
From a viewing distance of the 3fachen of the screen diagonals of a 16:9 TVs or of the 3,5fachen of a 4:3 TVs a TV picture cannot be seen more sharply or more highly detailed than a good PAL picture. Because the dissolution which can be seen corresponds to the dissolution of a TV of picture with 336 dpi, which is regarded from 25 cm.
typical examples of PAL display formats, which do not have to be entzerrt:
with non-square pixels are necessary an indication concerning the aspect ratio of the picture. Only so it can be indicated from the beginning distortion-free. Are usual:
- 960 × 576
- becomes occasionally with 16:9 - 720 ×
- 576 CCIR 601
- , DVDs, digital cameras etc. use productions. (Pixel clock: 13.5 MHz)
- 704 × 576
- similar television signal, with 13.5 MHz scanned (here the line is long instead of 53 ⅓ µs only 52 µs. This corresponds to 702 pixels. 704 is e.g. the next value divisible by 16.
- ) 544 ×
- 576. over DVB for cost saving by smaller necessary range
- 480 × 576
- e.g. to find with SVCDs. The reduced horizontal dissolution considers the Kellfaktor.
„PAL optimally “
deviating from above definition drives out the manufacturer Sharp under the designation „PAL optimally “ LCD - devices with only 540 lines of native vertical dissolution and in 16:9 - format (960 pixels). These televisions cut 36 lines to fig. off with SD -. The justification for this is that CRT - devices a similarly large Overscan would have and the range with type character box - is anyway black radiant emittance. The actual purpose is, the HDTV - formats 720p and 1080i without complex scaling to represent to be able, there 720/540 = 1 ½ and 1080/540 = 2. In a test of the magazine video the PAL could represent optimally to HDTV better than the HDTV of reference devices. Many 16:9 televisions have only 480 lines a dissolution. Tube televisions have however always a PAL optimized dissolution of at least 540 lines. If PAL on HDTV televisions is represented, good picture succeeds to these only rarely, since the PAL picture must be represented now in another raster.
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