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12-11-2014, 12:46 PM   #1
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contrast highlight/shadow adjustment

Moved from the K-5 to K-3 and while playing with the camera and the manual noticed "contrast highlight/shadow adjustment" I don't remember if it was on the K-5 (which I traded in).
any thought what might be the improvement changing these settings? I already noticed the changes in the metering between the 2 models.

Thanks
and thanks stevebrot for the great explanation about the high ISO noise reduction
https://www.pentaxforums.com/forums/172-pentax-k-3/282200-k-3-high-iso-noise-...-pictures.html


Ofer

12-11-2014, 12:56 PM   #2
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Shadow/highlight correction has been around for a while, but the K-3 introduces an "auto" mode as well as the ability to use ISO 100 even when highlight correction is enabled.

If you shoot in RAW, you get comparable results by underexposing by a stop then boosting the exposure by +1 (to fix highlights) and lifting shadows manually.

Adam
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12-11-2014, 01:00 PM   #3
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QuoteOriginally posted by Adam Quote
Shadow/highlight correction has been around for a while, but the K-3 introduces an "auto" mode as well as the ability to use ISO 100 even when highlight correction is enabled.

If you shoot in RAW, you get comparable results by underexposing by a stop then boosting the exposure by +1 (to fix highlights) and lifting shadows manually.
So is your recommendation to turn it off when shooting RAW? I have always kept both off on my K-5, and if in doubt underexpose then bring it up in LR.
12-11-2014, 02:33 PM - 1 Like   #4
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First of all to clarify, auto highlight compensation (HC) has been around for quite some time - and its implementation has been similar starting with the K-01 and K-30. Auto HC allows 100 ISO - and always has; turning on HC (forcing the implementation) increases ISO to 200 (dating to the K20D if not even further back). On the K-01 and K-30, the implementation of when Auto HC kicks in seemed perfect - triggering only when there is danger of blowout. Pretty much everyone who has given the Auto HC a full trial with those two cameras has it implemented all the time - as it triggers only when really needed (saving images). And there's no penalty because you still will be able to use ISO 100 most of the time. Also, the curve applied has no practical impact on shadow noise - because it is a very sophisticated curve implementation (not as simple as some have characterized it). In fact, the HC dynamic range curves (RAW and JPEG) look a lot like what Nikon implements as status quo with NO highlight compensation applied.

Unfortunately (IMHO), it appears that Pentax has implemented a more-conservative Auto HC approach with the K-3, and the potential for some blow-out before HC kicks in appears to be greater with this camera. I haven't tested it extensively with this camera (just got it about 10 days ago). You might need to underexpose slightly even with Auto HC set. Bottom line, Auto HC on the K-3 is highly unlikely to correct before you absolutely need it, or degrade the image in any way compared to the off setting. However, if you like steep roll offs into blow outs (a chronic Pentax problem in the CMOS era, frankly), or want to try to figure out exactly how much you want to underexpose and figure out how to post-process to compensate (but never quite as good as the camera does it, honestly) - feel free to go that route.

As has been reported quite often here - highlight comp applies to both RAW and JPEG, shadow comp applies only to JPEG.

12-12-2014, 12:06 AM   #5
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Thanks guys for the prompt reply. I've been using shadows compensation for long on my K-5 that really "enhanced" the dynamic range of the lighting option in JPG.
My question was aimed to the (I thought new) feature that appears when you set your overall contrast setting. in this option (page 55 in the English manual ) you can change the Shadows / Highlight Contrast . In my k200 and k-5 I've added 2 steps to the contrast set-point and in the new K-3 I saw additional break to shadow / highlight contrast adjustment
12-12-2014, 02:29 PM   #6
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Yes, that's a new function. Even the Prime processor cameras (K-30 etc.) didn't have that control. I shoot RAW mostly, but like to have my JPEGs get close to where I like the finished product. I tend to want less contrast than most. I worry about blowout, and artifacts in the JPEGs (especially if for some reason the job calls for JPEGs). So I set both the High and Low contrast down one notch - but guarding against blowout should be a higher priority. Then again, I also set JPEG down somewhat in contrast.

Those are settings worth playing with, and finding what pleases you. I like that level of adjustability. Not many people like the way Pentax sets up JPEG defaults, but it sure is possible to get exactly what you want in the adjustments.
12-12-2014, 02:59 PM - 5 Likes   #7
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Those two supplementary sliders affect the extremes of the jpeg tone curve. I struggled to understand what they did at first. Since they are called "contrast", I assumed they adjusted the tone curve steepness in the dark and bright ends. But that's not it.

It's a bit simpler:
Shadow contrast +/- makes the dark parts of the image brighter/darker respectively.
Highlight contrast +/- makes the bright parts of the image brighter/darker respectively.

You know how the "reversal film" custom image makes all dark parts go black? You can make the other custom images do the same thing by setting shadow contrast to -4. I think it's called "crushing the blacks" in some parts of the world.

Here's how to experiment:
1. Take a normally exposed shot of an average scene with suitable contrast. Nothing blown, nothing too dark. Save as RAW.
2. Use in-camera RAW development to develop that RAW file in 5 different ways, namely (A) neutral, (B) highlight contrast -4,
(C) highlight contrast +4, (D) shadow contrast -4, (E) shadow contrast +4.
3. Flick between these 5 different images in playback and study how the dark and bright parts differ.

It's a subtle effect. I don't use it much. I've set shadow contrast to -3 on my "Bright" custom image for extra dark blacks when the scene really needs some punch to work.

Regards,
--Anders.
12-12-2014, 04:18 PM   #8
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Asp1880,

That's a terrific explanation, and a fine recommendation on how to measure the impact of these settings.

Bad on Pentax for implementation, though. Adding shadow contrast to make the dark areas black should be done with a +, don't you think? Less contrast is more midtones by definition. I guess its due to the naming convention related to monitors. The term "contrast" really refers to "brightness." This also makes me wonder if the control for regular "contrast" really applies to the amount of brightness.

12-13-2014, 02:54 AM   #9
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Anders , Thank you for the explanation !!
Jim I agree with you - you know I am training engineers and technicians for years and most of the time I identify the RTFM problem (Read The F.cked Manual)
I will follows the steps to try out and maybe will save a setting in a user profile for quick change between them.
Again thanks for the time/attention answering me
Ofer
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