Where does 14400 come from, and why doesn't it change? - General Help and Assistance on using CHDK stable releases - CHDK Forum

Where does 14400 come from, and why doesn't it change?

  • 4 Replies
  • 177 Views
Where does 14400 come from, and why doesn't it change?
« on: 11 / May / 2022, 02:57:11 »
Advertisements
@reyalp

In playing around with get_live_histo() I've noticed, and am confused, by the the fact that the returned total count is always 14400, no matter what the exposure, ie highly under or over.

I've looked at the histogram.c source and I just don't get it.

Can you throw any light on the 'CHDK constant' ;-)

*

Offline reyalp

  • ******
  • 13668
Re: Where does 14400 come from, and why doesn't it change?
« Reply #1 on: 11 / May / 2022, 03:00:20 »
@reyalp

In playing around with get_live_histo() I've noticed, and am confused, by the the fact that the returned total count is always 14400, no matter what the exposure, ie highly under or over.
That's the total number of pixels sampled, so it should only change if the viewport dimensions are changed. It's returned so you can convert bins to percent without adding them all up yourself first.
Don't forget what the H stands for.

Re: Where does 14400 come from, and why doesn't it change?
« Reply #2 on: 11 / May / 2022, 03:04:20 »
OK.

But on a camera specific basis, why would the viewport change? Aspect ratio change, maybe?

*

Offline reyalp

  • ******
  • 13668
Re: Where does 14400 come from, and why doesn't it change?
« Reply #3 on: 11 / May / 2022, 03:24:56 »
But on a camera specific basis, why would the viewport change? Aspect ratio change, maybe?
Yes, aspect ratio is one reason. Can also vary by display device (LCD/EVF/HDMI/analog video), shooting mode (video vs still, some special scene modes), digital zoom...
Don't forget what the H stands for.


Re: Where does 14400 come from, and why doesn't it change?
« Reply #4 on: 11 / May / 2022, 03:29:42 »
Just checked the EVF, which reports 14706, as opposed to the LCD 14400.
Thanks for the insight.

 

Related Topics