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03-13-2010, 09:55 AM   #1
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K7 - colour settings for accurate RAW histogram?

I know the best method to get an accurate histogram would be to use UniWB, but I hate the green tint

So... I was wondering if anyone could suggest some colour settings (colour style, saturation,contrast, etc) for K7, that would help in getting a histogram close to what that of the RAW file is.
(right now I have the camera set to Natural with -1 Sat, -2 Contrast, -1 Highlight and Shadow Contrast)


While we're at it, even if this might be better fit for the PP subforums, I'll ask anyway:

Any recommended settings for Lightroom, to replace the default values it gives? (with Sony DSLRs, I had to make a lot of changes to get a... 'truer' default rendition of RAWs)

03-13-2010, 12:36 PM   #2
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Well, for those shots that really need accurate histograms, I set my USER mode to UniWB with Av mode... So the green tint does not invade my everyday shots (and the videos too! what a dumb idea to share pics and videos settings!!!)

Otherwise, everyday I use my slightly desaturated AWB Av mode, knowing that the only channel remotely accurate is the Green one in daylight, that under Tungsten the Red is pretty accurate too, and Blue for shadows...
03-13-2010, 04:30 PM   #3
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Settings for an Accurate Histogram
03-13-2010, 05:49 PM   #4
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cezar, I've asked this question (for the K100D and now the K20) several different ways on this and other forums, and it's really just a crap shoot. Because no manufacturer will divulge the inner workings of its camera settings and algorithms, the general response is that it's almost impossible to get the in-camera jpeg rendering to match the RAW output. It seems obvious that every dslr owner would expect/demand this, but apparently not... or at least not enough to force manufacturers to give the information up. You can experiment, and try and come as close as possible, build custom settings in RAW that approximate it, but that's about it. By the way, I'd love to be proved wrong on this. Good luck,
Brian

03-14-2010, 12:04 AM   #5
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Many thanks!

I guess I'll go ahead and bring the contrast to a minium, and then try out the other colour settings and see what I get

I wasn't really expecting to get settings for an 'exact' histogram reading in-camera, but something that wouldn't be too far off, without using UniWB.
03-15-2010, 08:12 AM   #6
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I just found this forum discussion about the article I linked to above:
"Settings for an Accurate Histogram": WB? - Luminous Landscape Forum
03-15-2010, 03:11 PM   #7
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QuoteOriginally posted by dlacouture Quote
Well, for those shots that really need accurate histograms, I set my USER mode to UniWB with Av mode... So the green tint does not invade my everyday shots (and the videos too! what a dumb idea to share pics and videos settings!!!)
So how do you get the K7 to apply UniWB? did you go through all the pain of shooting charts, filters, etc? or is there a file available like there is for canon and nikon, that you just save as custom WB?

thanks
03-16-2010, 01:36 AM   #8
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Well, that's easy : use a completely overexposed pic as a custom WB...
All the channels will be equals then...

I'm also wondering about using aRGB, as it seems to have an effect on the histogram...

03-16-2010, 01:43 AM   #9
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I've had some... disappointing results from UniWB on a trip to Cornwall last year so now I prefer to not use it at all, hence my original question.

But I'm not saying there's anything wrong with UniWB itself, it was probably just 'user error'
03-16-2010, 02:14 AM   #10
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CezarL, what kind of results?

I'm rather mitigated about UniWB myself, so I'd love to hear others' opinions...

In fact, it's useful for the Red and Blue channels only...
03-16-2010, 03:11 AM   #11
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Well... usually I was getting a histogram that looked underexposed (with a lot of headroom towards highlights, that is). So I would add +0.3 EV hoping to get as far to the right as possible, but with this adjustment I got clipped highlights. Since it wasn't too much compensation added, I thought it might be an error and that I would be able to recover in PP.
As it turned out, I couldn't save most of the shots taken this way, highlight recovery in Lightroom couldn't recover that darn overexposure (it happened mostly in sky areas shot with an ultrawide, but with the sun out of the frame), even if it was in very small regions of the capture. As for those that were originally showing underexposure, the in-camera histogram was accurate enough... as in, they were waaay underexposed (but then again, +0.3EV was giving overexposure!)


Maybe it was because I didn't use any special charts or extensive testing, and relied on the metering of a very bright area, when setting UniWB. Maybe it was something very wrong with both my cameras.
I really don't know what to say... just that I won't be using UniWB again in the near future.
03-16-2010, 03:36 AM   #12
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Well, using UniWB on my K7, I found that pics got indeed clipped before the histograms...
It was shown in the histograms as a peak 3-4 pixels from the extreme right...
03-16-2010, 03:41 AM   #13
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Yep... I was getting about the same amount on A100 and A700, if I remember correctly.

It's up to you if you want to live with that, or not.
I've found that, with good settings for the colour styles (together with tweaks to the default LR settings), I was getting good enough results on my Sony DSLRs, at least for my needs (not perfect histogram reading, but close to what I would see in LR after importing the RAWs).
03-17-2010, 11:48 AM   #14
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cezar, perhaps there is a way to use EXIF data to construct a RAW profile using the data and the RAW+jpeg feature?

I'm only taking a very uninformed guess at this, but in a RAW+jpeg shot on my K20, I see lots of color data (things like the Red/Green/Blue "Matrix Columns") in the jpeg EXIF that would seem to be defining the histogram construct we see on the camera's LCD. If so, there should be a way to extract those numbers, set them as a RAW-profile and end up with a baseline histogram on the RAW image that is very similar to what is seen in the in-camera jpeg histogram.

Again, this is way above my pay grade and I'm just speculating with no real understanding, but it's an idea for somebody with expertise to either pick up, or shoot down,
Brian
03-17-2010, 01:53 PM   #15
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Try this...

This method works for me (K-7 + variety of lens):

I keep all jpg settings at neutral (zero'd out, not +1, -1 or any other choice).

I shoot, then chimp (check the histogram of the recorded pic) to see if the right side of the histogram is just barely touching the Y-axis. If it's close but could use a nudge more, I'll increase by one or two wheel clicks...Since I shoot mostly landscapes and prefer manual mode, I'll decrease the speed to let more light in. I want the aperture and ISO kept constant. The obvious object of my plan is to get the histogram as close to the right side without touching.

When viewed in ACR, I find there's just a tiny amount of overexposure, easily correctable. I'm sure it would be similarly correctable in LR; both ACR and LR use the same raw engine.

I've also started doing blended exposures in Photoshop which requires two pics, to help achieve the best in both highlights and shadows. To do this, I take a second RAW shot, this time attempting to have the histogram barely touch the left side. (Exposing to the left?). It usually takes several tries to get both a best-for-highlights and best-for-shadows pic.

BTW, my favorite tutorial on blending exposures is Adobe Photoshop Tutorials | High Dynamic Range | Adobe Camera Raw | Layers Magazine

Hope this helps.

-Lew
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