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08-23-2009, 10:47 AM   #1
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Shadow Compensation

Any research into what it actually does? We know what D-Range does (now known as highlight compensation on K-7?), it underexposes and pulls the shadows up to keep the highlights from clipping. Also, it stores the kind of information in the RAW file but of course doesn't edit the raw data.

What does shadow compensation do? Does it simply pull the shadows up without exposing more or less? Does it change the highlight clipping point? How does it work with highlight compensation which already pulls up the shadows? It simply pulls them up higher than what metering thought they should be?

Although it will kill contrast and bring more noise in the shadows, I see it as a bit useful for mid-day shooting with harsh shadows when I want to do less PP - like shooting little league sports at noon. Gotta get a picture of every kid but the quality does not need to be spectacular. Is it that much worse than doing it by hand?

08-24-2009, 03:25 AM   #2
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From my observation, turning on Shadow Compensation does not change the actual exposure one bit.
My guess is the sensor actually captures a fair bit more information in the shadows than the normal JPEG range is able to show. Its the same way you are able to recover shadow details from a RAW file. Shadow Compensation just makes visible the bit in the shadows which would otherwise show as "Black" or nearly so, in the JPEG.
The camera pulls in the histogram at the far left , but leaves most of the rest of the histogram alone. Of course, when that kind of software-based "amplification" is applied, the noise gets amplified as well.
But the noisy bit is still usable, most of the time, and its better than not seeing any details at all.
Whether to use Shadow Compensation all depends on the situation. Sometimes I care about what's in the shadow area, sometimes I don't.

If you use the Pentax Photo Laboratory software which came with the camera, it allows you to apply the exact working of Shadow Correction (but not Highlight Correction) to the RAW file.
So Shadow Correction is purely software work.

Last edited by kittykat46; 08-24-2009 at 03:50 AM.
08-24-2009, 05:32 AM   #3
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QuoteOriginally posted by kittykat46 Quote
So Shadow Correction is purely software work.
I think Olympus does it a lot and most users like the results. Also, when combined with noise reduction, it gives you much better scores in dynamic range tests. So. I wonder if it isn't applied in some green modes

Afterwards, it is easier to undo shadow correction on a JPG later rather than to apply. Did anybody shoot greyscales in the various modes?
08-24-2009, 05:38 AM   #4
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I did some playing with this on my K7

What is seems to do is to modify the conversion to JPEG and increase the dynamic range in the low end.

By this whai I mean is that while it does not change the metering and the greyscale value of the point that is metered on, (these still appear at about 110 greyscale in the histogram) I found it elevated the greyscale value of the shadow detail.

I took a test shot at a lily with a lot of dark green foliage in off the metering spot. The lilly exposure stayed exactly the same in both shots, (shadow detail off vs maximum) but, while shadow detail in the normal shot came up with greyscale of about 15, in the shadow detail set to maximum it came up at about 35.

In this range it represents in my estimate an increase of over 1 full stop in dynamic range

Just a note about JPEG greyscale.

On my K10 and *istD the camera meters to a greyscale value of about 110. with contrast set to normal close to the nominal value each stop is a change in greyscale of about 45, so that in total there is a range of about 25-230 greyscale (4 1/2 stops) which is linear. below 25 and above 230 the next stop has a change og greyscale of 15, (i.e. 10 or 245 respectively) the next stop has a greyscale change of abotu 7-10 of about 5-8 or 248-250 respectively)

The way to test ths function is to take a series of shoits in manual mode, meter at a fairly low shutter speed, (1/50 for example)

Then change shutter speed (increase it ) and plot the greyscale vs shutter speed

Last edited by Lowell Goudge; 08-24-2009 at 05:58 AM.

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