Editing Standard-definition television (section)

== Pixel aspect ratio ==
{| class="wikitable"
|+ [[Pixel aspect ratio]]s for the scaling of various kinds of SDTV video lines
! Video format
! Display aspect ratio (DAR)
! Resolution
! Pixel aspect ratio (PAR)
! After horizontal scaling
|-
| rowspan="2" | [[480i]]
| rowspan="2" | 4:3
| {{resx|704×480}} ([[Raster interrupt|horizontal blanking]] cropped)
| rowspan="2" | 10:11
| {{resx|640×480}}
|-
| {{resx|720×480}} (full frame)
| {{resx|655×480}}
|-
| rowspan="2" | [[480i]]
| rowspan="2" | 16:9
| {{resx|704×480}} ([[Raster interrupt|horizontal blanking]] cropped)
| rowspan="2" | 40:33
| {{resx|854×480}}
|-
| {{resx|720×480}} (full frame)
| {{resx|873×480}}
|-
|-
| rowspan="2" | [[576i]]
| rowspan="2" | 4:3
| {{resx|704×576}} ([[Raster interrupt|horizontal blanking]] cropped)
| rowspan="2" | 12:11
| {{resx|768×576}}
|-
| {{resx|720×576}} (full frame)
| {{resx|788×576}}
|-
| rowspan="2" | [[576i]]
| rowspan="2" | 16:9
| {{resx|704×576}} ([[Raster interrupt|horizontal blanking]] cropped)
| rowspan="2" | 16:11
| {{resx|1024×576}}
|-
| {{resx|720×576}} (full frame)
| {{resx|1050×576}}
|}

The pixel aspect ratio is the same for 720- and 704-pixel resolutions because the visible image (be it 4:3 or 16:9) is contained in the center 704 horizontal pixels of the digital frame. In the case of a digital video line having 720 horizontal pixels (including horizontal blanking), only the center 704 pixels contain the actual 4:3 or 16:9 image, and the 8-pixel-wide stripes on either side are called [[nominal analog blanking]] or [[horizontal blanking]] and should be discarded when displaying the image. Nominal analog blanking should not be confused with [[overscan]], as overscan areas are part of the actual 4:3 or 16:9 image.

For [[SMPTE 259M-C]] compliance, an SDTV broadcast image is scaled to 720 pixels wide for every 480 NTSC (or 576 PAL) lines of the image with the amount of non-proportional line scaling dependent on either the display or [[pixel aspect ratio]]. Only 704 center pixels contain the actual image and 16 pixels are reserved for horizontal blanking, though a number of broadcasters fill the whole 720 frames.{{cn|date=April 2024}} The display ratio for broadcast widescreen is commonly 16:9 (pixel aspect ratio of 40:33 for [[anamorphic widescreen|anamorphic]]); the display ratio for a traditional or [[letterboxed]] broadcast is 4:3 (pixel aspect ratio of 10:11).

An SDTV image outside the constraints of the SMPTE standards requires no non-proportional scaling with 640 pixels (defined by the adopted IBM [[VGA]] standard) for every line of the image. The display and pixel aspect ratio is generally not required with the line height defining the aspect. For widescreen 16:9, 360 lines define a widescreen image and for traditional 4:3, 480 lines define an image.