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02-03-2014, 08:03 PM   #1
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Another Raw/jpeg

I have my K30 set for raw+.
I just transferred a bunch of pics of the kids snowboarding and could not believe the difference between the raw and the jpeg. Each jpeg appears to by way under exposed.
The raw files seem to be right on, with white snow and good color saturation on everything else.

Had I taken the pics with jpeg only, I would have been wondering what was wrong with the me, or the camera.
Can the processing brains of the camera not be trusted?

02-03-2014, 08:22 PM   #2
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One generally must overexpose one to two stops for snow to be rendered white.

Per that rule your RAW images ought to be underexposed as well as the JPGs. That the RAW images are differently exposed than the JPGs is a bit baffling.
02-03-2014, 08:30 PM   #3
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QuoteOriginally posted by JerD Quote
Can the processing brains of the camera not be trusted?
To some extent yes, as long as the correct brain is chosen. For example, what white balance setting did you have the camera set at? Could that be the reason all the JPG have been darkened?
02-03-2014, 08:42 PM - 1 Like   #4
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Is your raw converter set to 'auto-adjust' or something similar on import?

02-03-2014, 08:45 PM   #5
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QuoteOriginally posted by BrianR Quote
Is your raw converter set to 'auto-adjust' or something similar on import?
That would be another brain at work and possibly at fault. One more question - are you using the same program to view both? For any one image, does the histogram of the JPG look like a shifted version of the RAW image, or does it look like more has been done to modify the image?
02-03-2014, 08:56 PM   #6
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WB was set to cloudy
The first pic is the raw file with no editing, just saved in Picasa as a jpeg. The second image is the unaltered jpeg from the k30

[IMG][/IMG]

[IMG][/IMG]
02-03-2014, 09:00 PM   #7
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What application are you viewing the raw files in? Depending on the application, it could be doing some processing to the raw files before rendering to the screen, or it may even just be displaying the small 'preview' JPEG file that is stored within each raw file and you are not seeing the actual raw data.

Generally, it would be expected that snow photos are underexposed unless some positive exposure compensation is dialled in (as metering wants to achieve a mid grey outcome as an average across the screen, therefore wants to darken a snowy white scene. Unprocessed raw can look a bit darker/flatter that a processed jpeg typically, so your experience is a bit the other way to what I would expect. One thought - the JPEG processing is set to use the sRGB colour space? If Adobe RGB, your computer is probably unable to display the wider gamut correctly. The raw file is independent of the colour space setting and wouldn't be upset by Abobe RGB being set in the camera.
02-03-2014, 09:18 PM   #8
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QuoteOriginally posted by JerD Quote
WB was set to cloudy
I believe that is the source of your problem. If the camera thinks it is a cloudy day, it is expecting average, diffuse lighting, and thus that the average of your background should be close to the 18% grey. But your background is mostly white. I don't know if you have a copy of the Pentax DCU (came with my K-5) but that will let you reprocess the images as if you were using the camera settings. I bet if you used a different white balance; and one that by default brightened images, they would all come out looking okay.

02-04-2014, 11:47 AM   #9
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QuoteOriginally posted by Ole Quote
One generally must overexpose one to two stops for snow to be rendered white.

Per that rule your RAW images ought to be underexposed as well as the JPGs. That the RAW images are differently exposed than the JPGs is a bit baffling.
I agree and the OPs later post shows exactly this
QuoteOriginally posted by MSL Quote
I believe that is the source of your problem. If the camera thinks it is a cloudy day, it is expecting average, diffuse lighting, and thus that the average of your background should be close to the 18% grey. But your background is mostly white. I don't know if you have a copy of the Pentax DCU (came with my K-5) but that will let you reprocess the images as if you were using the camera settings. I bet if you used a different white balance; and one that by default brightened images, they would all come out looking okay.
this is wrong. The WB does not make assumptions about direct vs diffuse light only on the color temperature. The camera exposed correctly for metering white snow. It is important to remember the camera will try to meter for a "middle grey" solution, which is what the op got.


In fact this is nothing to do with raw vs joeg, it is all to do with understanding the camera and metering.
02-04-2014, 12:01 PM   #10
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QuoteOriginally posted by JerD Quote
The first pic is the raw file with no editing, just saved in Picasa as a jpeg.
Are you sure Picasa isn't applying an auto-correction to imported raw files?
02-04-2014, 12:02 PM   #11
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QuoteOriginally posted by Lowell Goudge Quote
In fact this is nothing to do with raw vs joeg, it is all to do with understanding the camera and metering.
Lowell - why are the two images different then? I'll accept that they are underexposed as shot, and so I can only assume that PIcassa automatically brightened them as it developed the RAW and chose a particular white balance or overall histogram setting to target. In other words, my explanation may not be right, but you didn't really answer why the two images are so different.

(typed my message as Parallax posted his)
02-04-2014, 12:58 PM   #12
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I looked around a little and it seems that Picaso does an automatic adjustment. And it seems it can't be turned off.
02-04-2014, 03:27 PM   #13
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QuoteOriginally posted by MSL Quote
Lowell - why are the two images different then? I'll accept that they are underexposed as shot, and so I can only assume that PIcassa automatically brightened them as it developed the RAW and chose a particular white balance or overall histogram setting to target. In other words, my explanation may not be right, but you didn't really answer why the two images are so different.

(typed my message as Parallax posted his)
Note that JPEG is set up based upon the meter readings of the camera and camera settings. When you import RAW the import routines vary from program to program. I use Corel PSP XV which allows for different RAW imports from "use JPEG settings" to others including using a preset conversion to letting the program "interpret" the scene itself and make adjustments based upon scene composition.

Your program is doing this and boosting the levels, it is not because anything was done wrong in the camera, just that the program applied post processing after. You can make the same adjustments to the JPEG image also.
02-04-2014, 03:43 PM   #14
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So the irony of the situation is that his camera isn't processing the JPG files so they are coming out dark, whereas the RAW files are being subjected to Picassa's default and unalterable processing and showing up properly corrected.
02-04-2014, 04:07 PM   #15
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QuoteOriginally posted by MSL Quote
So the irony of the situation is that his camera isn't processing the JPG files so they are coming out dark, whereas the RAW files are being subjected to Picassa's default and unalterable processing and showing up properly corrected.
They are not unalterable, they are the programs starting point. Nothing says you can't adjust down to a point between the two
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