Analog vs. Digital Resolution – TV Lines (TVL) vs. Pixels

October 19, 2009 by
Filed under: CCTV Articles, Comparisons, General Technology, Guides 

One of the most confusing and difficult topics in the CCTV world is resolution. Most of us have digital cameras or video camcorders and have heard the term megapixel used as the most common comparison in resolution between various makes and models. We are also aware that a larger number means better picture quality, but many people do not know why. In the CCTV security camera world, though, most cameras are still analog and their resolution is measured differently from what we are used to.

When measuring analog resolution, a TV line does not have a defined number of individual pixels. Instead, the term “TV lines” refers to the number of discernable horizontal or vertical lines on the screen. Analog security cameras are measured in Analog TV Lines, and most of them have between 420 and 580. The higher number of TV Lines, the more information captured. These types of cameras connect to a security DVR or CCTV VCR via coaxial video cable.

A pixel is the smallest element of a digital image. We have all zoomed too far into a picture from a website and seen the image go from clear to a bunch of colored squares – each one of those squares is an individual pixel. A megapixel (MP) is 1 million pixels, and is a specific measurement for digital resolution that encompasses the area of the output video.
Example: If a camera outputs a signal that is 1280×1024 pixels, it is shooting at a megapixel resolution of 1280 x 1024 = 1,310,720 pixels = 1.3 Megapixels (MP).

The most common type of digital security cameras are IP Cameras. These, like your digital camera at home, use strictly digital resolution. They utilize a network connection to either act as a standalone device or connect to a network-based DVR (Digital Video Recorder) or NVR (Network Video Recorder). IP Cameras have fixed resolutions and are now approaching, and in several cases exceeding, 1 megapixel in resolution, on average. Many of these cameras also support POE (Power Over Ethernet), which allows them to be powered by the Ethernet cable used for network connectivity, and PTZ (Pan Tilt Zoom), allowing for remote control of the pan, tilt and zoom features, if applicable.

I hope this helped everyone distinguish the differences between Analog (TV Line) and Digital (Pixel) Resolution. We would love to know what you think of our articles, and if you have any further questions, don’t hesitate to leave a comment!

Comments

22 Comments on Analog vs. Digital Resolution – TV Lines (TVL) vs. Pixels

  1. Bradley on Mon, 19th Oct 2009 4:27 pm
  2. Great post! I was looking across the web and came across these different resolutions for Analog and IP Cameras:

    Type Horizontal Vertical Resolution
    ————————————–
    CIF 320 240
    VGA 640 480 VGA
    WVGA 752 480 WVGA
    SXGA 1280 1024 1 Megapixel
    UXGA 1600 1200 2 Megapixel
    QXGA 2048 1536 3 Megapixel
    QSXGA 2560 2048 5 Megapixel

    If these are correct, hopefully, they will assist in helping others learn the difference between Analog and IP resolutions.

  3. Alvis N. on Mon, 19th Oct 2009 5:33 pm
  4. I like your expanation of this information. When is it best to use a megapixal camera over analog type? Is outdoor use ok for megapixal too?

  5. LQ on Tue, 20th Oct 2009 4:56 am
  6. Thanks for the info

  7. ARK_Alum on Tue, 20th Oct 2009 10:34 am
  8. Very interesting.

  9. BKR on Tue, 20th Oct 2009 5:08 pm
  10. would an analog camera with 480TVL be similar to 640×480 resolution?

  11. Jon Hough on Wed, 21st Oct 2009 12:46 pm
  12. Alvis N. :I like your expanation of this information. When is it best to use a megapixal camera over analog type? Is outdoor use ok for megapixal too?

    Megapixel and better resolution IP cameras capture more detail in a given image than their analog cousins. This means if you set 1 of each type with the same lense size up to capture an identical view, the megapixel camera will have more image detail in its picture. another advantage to IP cameras is that they use CAT5 network cable and do not have to be directly connected to the DVR, many of them have thier own web server built in and can be viewed independant of a DVR. This is great for locations that just need one camera to purchase a standalone IP camera and connect it to their network and view from any PC on their network, and with just minor network configuration view it from any location on the internet. Some of them even have Software included to turn a PC into a recorder for the video.

    In answer to your outdoor use question, there are some IP megapixel cameras that are designed for outdoor use and are vandal resistant. Others can be placed in weather resistant housings allowing for outdoor use.

  13. jhough on Thu, 22nd Oct 2009 1:14 pm
  14. BKR :would an analog camera with 480TVL be similar to 640×480 resolution?

    BKR :would an analog camera with 480TVL be similar to 640×480 resolution?

    The short answer to your question is yes, but I will give you the more technical answer below.

    In precise technical terms, “lines of resolution” refers to the limit of visually resolvable lines per picture height (i.e. TVL/ph = TV Lines per Picture Height). In other words, it is measured by counting the number of horizontal or vertical black and white lines that can be distinguished on an area that is as wide as the picture is high.

    It is imposible to give an exact correlation between an analog and digital resolution, but in general you can take your digital resolution and devide by 1.33 (for a 4:3 aspect ratio) to get the effective TV Lines you are seeing. for example if you are recording at 640 x 480 (VGA Resolution) you have 640 horizontal lines of pixels by deviding 640 by 1.33 you get 481.2 meaning that to get the best detail possible at VGA resolution you need a camera that captures 480 TV Lines or better.

  15. izeby.com on Thu, 22nd Oct 2009 1:49 pm
  16. Analog vs Digital Resolution – TV Lines – Megapixel | The CCTV Blog…

    This is a great writeup on the differences between Analog & Digital Resolution and their applications. The guys over at ApexCCTV really know what they are doing and have created a fantastic resource for anyone looking to brush up on their knowledge…

  17. Manuel Ortega on Mon, 2nd Nov 2009 5:41 pm
  18. I understand now. Thank you for the commenting on resolution. Very useful information provided.

  19. Steven on Wed, 11th Nov 2009 12:41 am
  20. Thanks for the explanation of this comparison of terms. Until now I really didn’t know how to compare the two. Thanks.

  21. Jimmy on Wed, 11th Nov 2009 11:08 pm
  22. Thanks for this article. I have always had a hard time understanding the difference until now. The formuls for converting pixels to TV lines makes it much easier to get a feel for comparing the two resolutions. Thanks!!!

  23. Walte Call on Sun, 15th Nov 2009 2:34 pm
  24. Thanks a lot for interesting article. But I had difficulty navigating around your web site because I kept getting 502 bad gateway error. Just thought to let you know.

  25. dbk on Sun, 6th Dec 2009 6:13 am
  26. “Confusing and difficult” describes this article as well. Where there were opportunities to provide clear comparisons — which is what the title suggests that the article will do — it just rambles on through other well known facts.

    How does a 520 TVL compare to a 1.3 MP??
    TVL = MP equivalents???
    Obvious questions are obviously NOT answered.

    In your answer above (also Confusing), did you intend to say “HORIZONTAL digital resolution and divide by 1.33″? Not that this either would offer a real comparison or clear understanding.

  27. serdar Demir on Tue, 8th Dec 2009 6:00 pm
  28. Firstly i want to say something about megapixel cameras and their outdoor usage: As far as i know that most of Mgpxl. cameras has low illumination levels so i don’t recommend them for fence security or sort of outdoor applications.At night or low light conditions they are not effective, if you need you should choose IP67 housing+ IR illuminators.

    Another issue : Below information is taken from a white paper from my company, i have some extra information and graphical definitions about comparing TVL and CIF/D1 resolution etc. i’ll share with you if someone needs more info.
    Resolution (TVL – or TV Lines) is a monochrome specification that states how many black and white lines can be seen in a given area. With 480 active scan lines, we can see how the theoretical maximum vertical TVL resolution is directly affected by the number of scan lines. (Note: TVL is not equal to scan lines, but vertical TVL is affected by the number of scan lines.)

  29. Indradevi on Sun, 24th Jul 2011 8:34 pm
  30. I confused with the concept of tvl and pixels but this article gave me clear idea of both terms

  31. Bibhusan Tiwary on Wed, 31st Aug 2011 7:10 am
  32. differancate between the analog camera of cctv

  33. Mau on Thu, 5th Jan 2012 3:19 am
  34. what determines the number of tvlines a sensor (ccd) can support?
    For example I got the IXC404, no, in the specs nowhere it is saying the number of tvlines, Could you tell?

  35. brijesh patel on Sat, 7th Jan 2012 12:46 am
  36. nice article,
    it is rely help full to for me.

  37. kiran on Sun, 11th Mar 2012 10:46 pm
  38. thank you it’s helped me a lot.

  39. kiran on Sun, 11th Mar 2012 10:47 pm
  40. thank you

  41. dave on Wed, 18th Apr 2012 6:34 am
  42. What confuses me is Tiger direct has wired cameras that say analog and wired cameras that say digital. what is the difference?

  43. Harold D.M. Ingris on Sat, 30th Jun 2012 10:38 am
  44. Its like you read my mind! You appear to know so much about this, like you wrote the book in it or something. I think that you can do with a few pics to drive the message home a little bit, but other than that, this is excellent blog. A great read. I’ll definitely be back.

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