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04-11-2010, 12:00 AM   #1
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[K10D RAW+]Exposure difference between RAW and JPEG

I'm at the moment shooting RAW+. There seems to be an exposure difference between the JPEG and the RAW (PEF). I'm quite sure that that was not the case a while ago.

Attached the JPEG from the camera. JPEG engine settings set to 0, image tone set to natural. I will post the converted PEF (using UFRAW) in the next post.

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PENTAX K10D  Photo 
04-11-2010, 12:03 AM   #2
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And this is the converted PEF (without additional processing).

Is this indeed exposure or is there another setting that might have caused this.
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04-11-2010, 12:34 AM   #3
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Sterretje, UFRaw usually automatically calculates exposure correction unless you switch that off. Also make sure you have no curves or auto-blackpoint enabled and the color profile is set to "matrix".

It is normal, however, for the in-camera JPEG to differ slightly from a converted raw - be it in exposure, contrast, color or sharpness - every raw processor will have a slightly different "recipe" to cook the raw.

Your images look pretty consistent, I wouldn't worry about it!
04-11-2010, 01:15 AM   #4
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It's just the Pentax in camera processing, the older Pentax DSLRs have a horrible in camera processor that doesn't do any of the photos justice when you convert them in camera or just take JPEGs with it.

04-11-2010, 04:19 AM   #5
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Thanks for the replies. As stated, I'm quite sure that the in camera JPEGs looked the same as the PEFs in UFRAW (a while ago).
I did check UFRAW's settings and they look 'normal' (for a beginner in PP like me).

Below the UFRAW ID file
Code:
<?xml version="1.0" encoding="utf-8"?>
<UFRaw Version='7'>
<InputFilename>/home/fortyfourgalena/Pictures/IMGP7469.PEF</InputFilename>
<OutputFilename>/home/fortyfourgalena/Pictures/IMGP7469.pef2jpg.jpg</OutputFilename>
<Temperature>3811</Temperature>
<Green>1.027631</Green>
<ChannelMultipliers>1.421875 1.000000 1.644531</ChannelMultipliers>
<OutputType>4</OutputType>
<CreateID>1</CreateID>
<Compression>100</Compression>
<BaseLinearCurve Current='yes'>
</BaseLinearCurve>
<LinearCurve Current='yes'>
</LinearCurve>
<sRGBInputProfile Current='yes'>
</sRGBInputProfile>
<sRGBOutputProfile Current='yes'>
</sRGBOutputProfile>
<Make>PENTAX</Make>
<Model>K10D</Model>
<Timestamp>Sat Apr 10 16:04:01 2010</Timestamp>
<Orientation>0</Orientation>
<ISOSpeed>100</ISOSpeed>
<Shutter>1/250 s</Shutter>
<Aperture>F0</Aperture>
<FocalLength>200.0 mm</FocalLength>
<FocalLength35>300.0 mm</FocalLength35>
<EXIFSource>exiv2 0.16</EXIFSource>
<Crop>0 0 3896 2616</Crop>
<Log>
ufraw_open: w:3896 h:2616 curvesize:0
Reseting Exif.Image.Orientation from &apos;1&apos; to &apos;1&apos;
EXIF data read using exiv2, buflen 9148
Warning: Size 8230 of Exif.Pentax.0x0404 exceeds 4096 bytes limit. Not decoded.
Warning: Size 21608 of Exif.Pentax.0x0405 exceeds 4096 bytes limit. Not decoded.

Loading PENTAX K10D image from /home/fortyfourgalena/Pictures/IMGP7469.PEF ...
Black: 0, Maximum: 4095
Scaling with black 0, multipliers 0.864608 0.608076 1.000000 0.608076
Scaling with black 0, multipliers 0.864608 0.608076 1.000000 0.608076
AHD interpolation...
</Log>
</UFRaw>
I know I can adjust, but was a bit shocked that they were not the same; it's between 3/4 and 1 stop difference. Might be the subject that has an effect on how the JPEG engine in the camera works with the brightness.

Last edited by sterretje; 04-13-2010 at 12:29 AM. Reason: Corrected 4/4 to 3/4
04-12-2010, 10:30 PM   #6
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That's nowhere near a 1 stop difference. It's barely different at all, in fact, if you look at the highlights - only the shadows are noticeably darker. Suggesting that uffraw has a higher contrast setting or steeper pre-processing curve by default, but that's about the only real difference I see.
04-12-2010, 10:56 PM   #7
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What I am missing seems to be these three lines:

<ClipHighlights>film</ClipHighlights>
<AutoExposure>1</AutoExposure>
<AutoBlack>1</AutoBlack>

Which UFRaw version are you running? Which distro?
04-13-2010, 12:28 AM   #8
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@marc
I tried in ufraw to adjust to something that looked the same. At around +0.8 ev it started to look the same. There still might be something else that influences the perceived image (and I interprete it as ev. PS: I see I wrote 4/4 instead of 3/4; will correct shortly.

@newmikey
Ubuntu 8.04; not sure about UFRAW version; might be 0.16 but did not check (not behind my machine right now; it's the version that is in the repository)

04-13-2010, 12:35 AM   #9
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QuoteOriginally posted by sterretje Quote
@marc
I tried in ufraw to adjust to something that looked the same. At around +0.8 ev it started to look the same. There still might be something else that influences the perceived image (and I interprete it as ev. PS: I see I wrote 4/4 instead of 3/4; will correct shortly.

@newmikey
Ubuntu 8.04; not sure about UFRAW version; might be 0.16 but did not check (not behind my machine right now; it's the version that is in the repository)
Try adding in the extra lines in an text editor (Kwrite?Gedit?) and double-clicking the *.ufraw file.
04-13-2010, 02:06 AM   #10
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vi

I have a windows version as well (0.17 if I'm not mistaken) and will compare.
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