The resolution of SECAM (Séquentiel couleur à mémoire) is 720x576 pixels, sharing the same video specifications as the PAL television standard for picture dimensions.
Understanding SECAM Resolution
The 720x576 resolution defines the standard picture dimensions for the SECAM analog television broadcasting system. This specification means that an image is composed of 720 pixels horizontally and 576 pixels vertically. This resolution is a cornerstone of standard definition (SD) television in regions that historically adopted SECAM or PAL.
While the total number of lines in the SECAM system is 625, 576 of these lines are visible to the viewer, contributing to the vertical resolution. The 720 horizontal pixels represent the digital sampling equivalent for a traditional 4:3 aspect ratio video signal. This common resolution allowed for some compatibility and easier equipment manufacturing across different regions using PAL or SECAM. For more details on this global standard, you can explore information on Standard-definition television.
How SECAM Transmits Color Information
Despite sharing the same resolution, SECAM distinguishes itself from PAL in how it encodes and transmits color information. Unlike PAL, which uses a phase-alternating line system, SECAM transmits the two color difference signals (red minus luminance and blue minus luminance) sequentially, one line after the other. It uses frequency modulation for these color signals.
This unique sequential transmission method, developed in France, was designed to mitigate the color shifts or hue errors that could occasionally occur in PAL, although it introduced its own set of potential artifacts. Learn more about the technical specifics of SECAM encoding.
SECAM's Historical Context and Product Support
SECAM was primarily adopted in France, Eastern Europe, Russia, and various parts of Africa and the Middle East. It stood as one of the three major analog television color standards worldwide, alongside PAL and NTSC.
- Practical Insight: With the global transition to digital broadcasting standards such as DVB-T, ATSC, and ISDB-T, SECAM has largely become obsolete for general consumer use. Consequently, only a handful of products support SECAM today. Its continued relevance is primarily found in legacy equipment, archival systems, or in the historical study of broadcast technology.
Comparing Major Analog Color Television Standards
Understanding SECAM's resolution is often best done in the context of its contemporaries:
| Feature | SECAM | PAL | NTSC |
|---|---|---|---|
| Resolution | 720x576 | 720x576 | 720x480 |
| Vertical Lines | 625 (576 visible) | 625 (576 visible) | 525 (480 visible) |
| Field Rate | 50 Hz | 50 Hz | 60 Hz |
| Color Encoding | Sequential FM | Phase Alternating | Quadrature Amplitude Modulation |
| Common Regions | France, Russia, parts of Africa & Middle East | Western Europe, Australia, parts of Asia | North America, Japan, parts of South America |
Transition to Digital and Legacy Relevance
The 720x576 resolution characteristic of SECAM (and PAL) defined standard definition television for many parts of the world for several decades. However, with the advent and widespread adoption of high-definition (HD) and ultra-high-definition (UHD) television, analog standards like SECAM have been phased out in favor of digital formats.
- Legacy Relevance: For professionals involved in historical video archives, media preservation, or the conversion of old analog content, understanding SECAM's specific resolution is crucial. It helps in accurately digitizing and preparing these materials for modern playback and storage.
- Solution: When converting SECAM-encoded content to contemporary digital formats, the material is often either preserved at its native 720x576 resolution for archival purposes or upscaled to higher resolutions like 1280x720 (720p HD) or 1920x1080 (1080p Full HD) for improved viewing on modern displays, depending on the project's requirements.
