Shot_histo help

pigeonhill

1155

Shot_histo help

« on: 15 / July / 2020, 03:39:37 »

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UPDATE on an M3

Can anyone suggest the error of my ways in using shot_histo in Lua.
The section of the code looks like this:

Code: [Select]

shot_histo_enable(1)
myshoot()
histo_size=get_histo_range(-1) 
total_samples=get_histo_range(-2)

I get a Lua 'number expected' error.

« Last Edit: 15 / July / 2020, 04:02:04 by pigeonhill »

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c_joerg

1247

Re: Shot_histo help

« Reply #1 on: 15 / July / 2020, 04:23:36 »

The function need to parameters.

Code: [Select]

x=get_histo_range(1020,1023)

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M100 100a, M3 121a, G9x II (1.00c), 2*G1x (101a,100e), S110 (103a), SX50 (100c), SX230 (101a), S45,
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pigeonhill

1155

Re: Shot_histo help

« Reply #2 on: 15 / July / 2020, 04:29:00 »

@c_joerg

Yes I am aware of that, but using -1 etc is meant to give you some additional info, eg bit depth related.

But it doesn’t.

Maybe it’s the M3, ie 14bit depth?

Cheers

Garry

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pigeonhill

1155

Re: Shot_histo help

« Reply #3 on: 15 / July / 2020, 04:55:02 »

...plus just tried getting range info and only seem to get 0 or 100.

I’m thinking this call doesn’t work on the M3?

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c_joerg

1247

Re: Shot_histo help

« Reply #4 on: 15 / July / 2020, 05:15:58 »

Quote from: pigeonhill on 15 / July / 2020, 04:29:00

Maybe it’s the M3, ie 14bit depth?

G1x has also 14bit…And this is not a RAW Hist!!

Quote from: pigeonhill on 15 / July / 2020, 04:55:02

...plus just tried getting range info and only seem to get 0 or 100.

I think the range is independent from the cam 1024 steps.

Quote from: pigeonhill on 15 / July / 2020, 04:29:00

I’m thinking this call doesn’t work on the M3?

I never tried on M3…

« Last Edit: 15 / July / 2020, 05:17:33 by c_joerg »

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M100 100a, M3 121a, G9x II (1.00c), 2*G1x (101a,100e), S110 (103a), SX50 (100c), SX230 (101a), S45,
Flickr https://www.flickr.com/photos/136329431@N06/albums
YouTube https://www.youtube.com/channel/UCrTH0tHy9OYTVDzWIvXEMlw/videos?shelf_id=0&view=0&sort=dd

pigeonhill

1155

Re: Shot_histo help

« Reply #5 on: 15 / July / 2020, 05:29:14 »

@c_joerg

Thanks for the info, I thought the range may vary with bit depth.

Now I’ve got to asses how the 1024 steps correlate to Ev stops.

Cheers

Garry

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c_joerg

1247

Re: Shot_histo help

« Reply #6 on: 15 / July / 2020, 05:43:31 »

Quote from: pigeonhill on 15 / July / 2020, 05:29:14

Now I’ve got to asses how the 1024 steps correlate to Ev stops.

But the get_histo_range is not a RAW histogram.
The RAW Histogram is exactly correlated to Ev stops.
https://chdk.fandom.com/wiki/Lua/Raw_Hook_Operations

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M100 100a, M3 121a, G9x II (1.00c), 2*G1x (101a,100e), S110 (103a), SX50 (100c), SX230 (101a), S45,
Flickr https://www.flickr.com/photos/136329431@N06/albums
YouTube https://www.youtube.com/channel/UCrTH0tHy9OYTVDzWIvXEMlw/videos?shelf_id=0&view=0&sort=dd

pigeonhill

1155

Re: Shot_histo help

« Reply #7 on: 15 / July / 2020, 06:19:13 »

@c_joerg

Quote

But the get_histo_range is not a RAW histogram

Exactly ;-)

Thus I need to know how the data gets distributed from 1024 down.

In other words the top stop is not (likely) covered by 512-1024. It will be x-1024.

But what is x?

Anyway, functionally all working now in my landscape bracketing script, which will have an auto exposure bracketing option, ie: set the exposure for the dark end and the script will get brackets until ETTR condition is meet.

Thanks for your help...as always :-)

Cheers

Garry

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