Histogram - page 7 - General Discussion and Assistance - CHDK Forum
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Histogram

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Offline pigeonhill

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Re: Histogram
« Reply #60 on: 19 / January / 2013, 23:48:32 »
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Ok I was too intrigued to wait until tomorrow. Just tested and, yes, when you disable Canon RAW you can get  .dng image.

I'm not aware this difference between the S95 and G11 is captured on the CHDK web site. Or is it?

BTW is the EXIF data above sufficient, or do you wish me to upload a .dng from each camera to answer lapser's question?

Cheers

Garry
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Offline philmoz

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Re: Histogram
« Reply #61 on: 20 / January / 2013, 00:07:54 »
Quote from: pigeonhill on 19 / January / 2013, 23:48:32
Ok I was too intrigued to wait until tomorrow. Just tested and, yes, when you disable Canon RAW you can get  .dng image.

I'm not aware this difference between the S95 and G11 is captured on the CHDK web site. Or is it?

It's an obscure bit of code whose purpose is not clear; but I came across an old reference to it doing this on the G10 so thought there was a chance the G11 might behave the same. Like of lot of what's in CHDK it's not well documented.

Quote
BTW is the EXIF data above sufficient, or do you wish me to upload a .dng from each camera to answer lapser's question?

Please upload the DNG files.

Phil.
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Offline pigeonhill

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Re: Histogram
« Reply #62 on: 20 / January / 2013, 09:40:22 »
Phil/Anyone

Hope you can help?

Could you point me someone/somehow I can upload two DNG files to you?

Cheers

Garry
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Offline waterwingz

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Re: Histogram
« Reply #63 on: 20 / January / 2013, 09:49:48 »
Quote from: pigeonhill on 20 / January / 2013, 09:40:22
Could you point me someone/somehow I can upload two DNG files to you?
box.com ?
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Offline pigeonhill

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Re: Histogram
« Reply #64 on: 20 / January / 2013, 10:02:57 »
Phil/Lapser

I hope you can get at these files?

https://www.box.com/signup/collablink/d_597049076/7680152bd449c

Cheers

Garry
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Offline pigeonhill

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Re: Histogram
« Reply #65 on: 20 / January / 2013, 10:06:46 »
Waterwingz

Thanks for the box.com pointer.

Cheers

Garry
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Offline lapser

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Re: Histogram
« Reply #66 on: 20 / January / 2013, 15:16:29 »
Quote from: pigeonhill on 20 / January / 2013, 10:02:57
I hope you can get at these files?
I was able to download the files, and view them. On my viewer, it looks like the G11 has a black line at the top that isn't present on the S95. I'm not sure if this is the problem, but I am sure philmoz will figure it out.

There are a lot of little dots scattered throughout both images that look a little like hot pixels. Was this an ETTR image? I wonder if overexposing with ETTR is producing hot pixels. This might be something to investigate. What was the shutter time for the images?
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Offline waterwingz

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Re: Histogram
« Reply #67 on: 20 / January / 2013, 15:43:50 »
Quote from: lapser on 20 / January / 2013, 15:16:29
On my viewer, it looks like the G11 has a black line at the top that isn't present on the S95. I'm not sure if this is the problem, but I am sure philmoz will figure it out.
It all a question of how careful the person doing the original port was about setting CAM_ACTIVE_AREA parameters.  What you are supposed to do is start with the raw sensor size, take an image, and figure out what part of the sensor area is masked out,  and then reduce the CAM_ACTIVE_AREA appropriately.  Sounds like the G11 port was a few pixels off - or maybe the mask variation from camera to camera is enough to cause differences in the actual active area ?

Quote
There are a lot of little dots scattered throughout both images that look a little like hot pixels. Was this an ETTR image? I wonder if overexposing with ETTR is producing hot pixels. This might be something to investigate. What was the shutter time for the images?
If you are using DNG 1.3 with bad pixels correction off then this makes sense.
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Offline pigeonhill

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Re: Histogram
« Reply #68 on: 20 / January / 2013, 15:59:17 »
All

The two DNG exposures were nominal, at 0Ev.

Cheers

Garry
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Offline lapser

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Re: Histogram
« Reply #69 on: 20 / January / 2013, 16:26:28 »
Quote from: pigeonhill on 20 / January / 2013, 15:59:17
The two DNG exposures were nominal, at 0Ev.
Well, I'm not sure what the dots are. They could be part of the wall pattern, I suppose. Do you have something more uniform and gray you could try a test DNG with?
Quote from: waterwingz on 20 / January / 2013, 15:43:50
It all a question of how careful the person doing the original port was about setting CAM_ACTIVE_AREA parameters.  What you are supposed to do is start with the raw sensor size, take an image, and figure out what part of the sensor area is masked out,  and then reduce the CAM_ACTIVE_AREA appropriately.  Sounds like the G11 port was a few pixels off - or maybe the mask variation from camera to camera is enough to cause differences in the actual active area ?
I should probably assume the active area may be a little off, and shrink my histogram area a little. Maybe Rawdigger is doing that. Did you ever try it with shot_meter_enable(1,1,1,99,99) on the G11 to see if that fixes the problem?
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