Highlight and shadow control in settings

Quick question

In the camera menu settings there are shadow and highlight correction.

I have both of these turned off so I can control them PP and to speed the camera up as I hear with them on the write times are longer.

Does anyone use them and do they work or does it just grey out highlights rather than retain detail in them?

Hi Gareth, firstly, unless you use PDCU (Pentax Software), then these correction settings are only relevant for JPEG output. RAW files opened in other software will not have any way of acting on these settings. PDCU will apply them to it's opening image default, and then you can make further adjustments with the equivalent sliders in the software.

I have found the corrections to be of good quality, but avoid the highest setting. Then you can get grey looking whites and washed out backs. Generally the lower and mid settings compress the DR nicely while retaining reasonable contrast at the ends of the curve, and for JPEG use then I think they are a good thing to use instead of similar work on a computer later.

Thanks Nigel, I don't use that software so I'm guessing for me, the best thing is to not bother with them then and carry on as I have been!

Cheers

Yes, for your RAW files then they don't mean anything. I do sometimes switch to jpegs when I'm shooting loads of similar shots and don't want to bother with RAW processing, and I keep my shadow and highlight corrections on all the time. I don't think they affect the burst speed or writing speeds, I think it is only the distortion corrections and noise reduction that slow things down.

Actually, the highlight correction does affect RAW files. The shadow correction doesn't.

That is what I thought; highlight correction raises the minimum usable ISO by 1-stop - eg K5ii from iso 80 to iso160.

Sure, on the K7 it goes from 100 to 200 ..... But I was referring to the actual editing effect, what you can see actually happening to the highlights on the LCD .... That I do not think is reproduced by any other software than PDCU,, so unless you use PDCU then it does 'not apply' to RAW files (ie its 'not applied') .... Is that a logical way to see it?

But what is happening by increasing the minimum sensitivity? My guess is that it allows a localised gain/ sensitivity reduction (down from 200 to 100 on the K7) to be applied somehow to the areas that are detected as being in danger of burning out. And so it is in the RAW file for LR or any other programme to detect. Just my 2p worth!

That sounds feasible of course .... so by changing the actual exposure values that are recorded this will therefore be apparent no matter what programme is used ... ?

But I thought that Highlight Correction was a software process applied to the RAW data in the camera after the actual capture ..... ?

There is something about it in the K30 review on DPR and how it is used to expand the DR of the camera/ sensor

Thanks Andy, I'll take a look at that ..... It seems counter-intuitive don't you think? .....a higher ISO gives more dynamic range .... .... Maybe its another strange, mysterious process like dark frame subtraction!

The highlight correction is basically a digital fiddle - the camera underexposes by one stop (shoots at ISO one stop lower than set) and then does a 'histogram shift' so that the highlights are just under the clip limits. When I'd looked at the RAW histograms with RawDigger it seemed to be a straight linear multiply (on a K-5ii) - I suspect that the DPR K-30 curves are plotted from JPEGs after gamma mapping.

The shadow correction did not appear to do anything to the RAW values, again on a K-5ii.

I keep the highlight correction on all the time - it does what it is supposed to do - as long as you realise that it has only one stop range, any highlights brighter that that will still get clipped.

Thanks for that Karel. So yes Nigel it seems counter-intuitive, but you are increasing DR by applying lower ISO to the highlight areas. If you look at the graph on DPR you will see how the curve without the correction just goes linearly off scale at the top; apply the correction and it tapers off gradually.

Thanks for the explanations and extra points there guys, it's valuable knowledge for using the highlight correction feature, which seems to be good default choice, unless you specifically need the lowest ISO your camera has ....

I admit I mostly use ISO 200 unless working with flash or on a tripod. There doesn't seem to be much extra noise and the extra stop of 'speed' is worthwhile for steadiness. And now also the highlight correction is another good reason.