Sets Plus

PALplus is an extension of the PAL analogue broadcasting system for transmitting 16:9 programs without sacrificing vertical resolution. more...

Home
Boys
Girls
Infants & Toddlers
Men's Accessories
Men's Clothing
Uniforms
Adult
Lab Coats
Scouting
Scrubs
Bottoms
Bottoms Large
Bottoms Medium
Bottoms Other
Bottoms Plus
Bottoms Small
Bottoms X Large
Bottoms X Small
Lots
Other
Sets Large
Sets Medium
Sets Other
Sets Plus
Sets Small
Sets X Large
Sets X Small
Sets, 2 pieces
Tops
Tops Large
Tops Medium
Tops Other
Tops Plus
Tops Small
Tops X Large
Tops X Small
Boys
Girls
Vintage
Wedding Apparel
Women's Accessories,...
Women's Clothing

A standard PAL receiver will display the image in letterbox format with 432 active lines, while a PALplus receiver can use extra information hidden in the black bars above and below the image to recreate 576 lines of vertical resolution.

A special signal tells the receiver when PALplus is in use, and also whether the original content was interlaced ("Camera mode" 576i50) or progressive scanned ("Film mode" 576p25). An additional signal can enable a "Ghost Cancellation" feature.

A separate feature related to PALplus is ColorPlus, which improves colour decoding performance.

Operation

Without PALplus, a 16:9 presentation has only 432 lines of vertical resolution. This reproduces noticeably less detail than the 576 lines used for 4:3 broadcasts. A fully decoded PALplus broadcast restores the 576 line vertical resolution. For compatibility reasons, the horizontal bandwidth remains at 5.0 MHz. This means a PALplus signal provides no extra horizontal resolution to compensate for the image being stretched across a wider screen. The result is a horizontal resolution that is 73% of the vertical resolution, or 51% when the Kell factor is ignored.

Versions

The PALplus standard comprises three extensions to standard PAL:

1. Vertical helper

A broadcaster creates a PALplus signal by scaling an anamorphic 16:9 picture with 576 lines down to 432 lines, so that the picture appears letterboxed on a regular PAL TV set. For luminance, the scaling is done using a pair of matching low-pass and high-pass filters, with the low-pass result appearing in the broadcast. One out of every 4 lines of the high-pass result is then hidden in the remaining 144 black lines at the top and bottom of the picture, using the U colour subcarrier. The filtering is such that this is enough to restore the complete 576 line resolution. The use of the colour subcarrier means the signals sometimes appear as blue and yellow patterns on a regular PAL TV set. The 16:9 PAL-plus receiver combines 432 visible lines plus 144 helper lines into 576 new visible lines.

In Film mode (progressive), the operation is performed on a per-frame basis, while in Camera mode (interlaced) the operation is performed per-field.

2. Colour-plus (or Clean PAL)

The PAL colour carrier is modulated making use of correlation between 2 fields, in order to give a cleaner Y/C separation in the PAL-plus receiver. Colour pictures on both standard and PAL Plus receivers are enhanced.

Read more at Wikipedia.org