Nominal analogue blanking is the outermost part of the overscan of a standard definition digital television image.
The exact width is determined by taking the definition of the time required for an active line in PAL or NTSC, and multiplying it by the pixel clock of 13.5 MHz of Digital SDTV.
[citation needed] Notably, screen shapes and aspect ratios were defined in an era of purely analogue broadcasting for TV.
In fact, a purely digitally sourced SDTV image, with no analogue blanking, will be close to 788 × 576 or 655 × 480 once stretched to square pixels.
This means that a purely digitally sourced widescreen SDTV image, with no analogue blanking, will be close to 1050 × 576 or 873 × 480.