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ADV7183B Gain operation

KevinL
  •  Analog Employees 
on May 31, 2012

Please confirm or comment on these ADV7183B questions:

  1. the manual luma gain scales the whole signal from sync tip to peak white?
  2. the brightness only adds a DC offset on top of black?
  3. the contrast only scales the video above black?
  4. If I have my RANGE set to 16-235, and have a gain/brightness/contrast combo that is too high, it will clip the whites and saturate at 235, but everything else is normal and linear from black to the clipping point

Thank!!

  • 0 on Jun 5, 2012 2:55 PM over 8 years ago

    Hi KevinL,

    Firstly, we do not recommend the ADV7183B for new designs, Depending on the application, we would recommend the ADV7181C or ADV7401 or ADV7180.

    1. Yes -it scales the full signal

    2. Yes the brightness is an offset applied to the active video.

    3. Yes - only scales active video range.

    4. RANGE control is applied after the Gain/ brightness/contrast etc and scales the video to 16-235.

    Rgds,

    Ray

  • 0 on Jun 5, 2012 7:46 PM over 8 years ago

    Hi Kevin,

    RANGE bit scales to make the data fit into 16-235 range. It means that no output value will be above 235 or less than 16.

    So a x2 will be scaled to fit into 16-235.

    Rgds,

    Ray

  • 0
    •  Analog Employees 
    on Jun 5, 2012 8:05 PM over 8 years ago

    Hi, Ray,

    on the range control, how does it set the scale factor to scale to the 16-235 range? Is this an automatic scaling over a line or over a field or frame?

    response from my customer:

    "If I have a signal that maxes out at 235, RANGE leaves it alone. If I now apply x2 gain, RANGE will scale it to 235 (ie. divide by 2), or clip it to 235 (remove the top half)?

    Does this scaling/clipping apply to just the sample that exceeds 235, or the whole video line, or the whole field or frame containing this sample?"

    thanks!

  • 0
    •  Analog Employees 
    on Aug 2, 2018 4:37 PM over 2 years ago
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin