Experiments in sharpening

[kye]

I've gradually worked my way "up" from cameras that applied too much sharpening to less and less.  Typically they applied too much and so I got a bit familiar with blurring the image to soften it to get it to a good look.  

Now I own cameras that shoot in 1080p RAW and look completely silly without sharpening, and I realise I know very little about how to do that.  Interestingly, there aren't many tutorials around going through how to do it, even the basics aren't covered well.  Unlike topics such as how to apply a LUT, but I digress.

So, this thread is about me learning to apply sharpening, sharing what I find, and maybe getting some hints from others.

I've been taking screen captures from TV shows and movies as references for a long time (always a good thing to have when colour grading) and I thought I'd start by analysing these images first, then seeing what levels of sharpening come with the various cameras I have.  I've compiled a bunch of source footage from my projects over the years as references.

So, here's how it works..   I put a bunch of images onto a 1080p timeline, and then by some Resolve trickery, we can highlight areas of strong edges in red, medium strength edges in blue, and weak edges in green.

Happy to describe the node tree if anyone is curious, but it turns images like this:

Into outputs like this:

I've looked at a range of images from Peaky Blinders, Chefs Table, S.W.A.T. and Unabom and they all appear to have similar levels of sharpening.  For images where there is very harsh lighting and/or strong detail on faces (such as facial hair) the face texture just dips into the blue, but is green.  For images that are softly lit and are of female leads who are meant to appear with smoother skin those areas of skin don't get any green highlighting, such as this:

or this:

but other than those things, people tend to get green highlights on the lighter areas of skin and not in the shadow areas, and blue on specular highlights:

Now to analyse my images.  I'm looking at footage shot on XC10 in 4K, GH5 in 1080 120p, 4k60, 4k25, and 5k25, iPhone 4k60 and 4k25, Sony X3000 4k25, and BMMCC/BMPCC 1080p RAW or Prores HQ.

More to come.

[MrSMW]

Interesting…

Prior to Fuji XH1 shooting 1080 50p, I had no idea what I was doing.

I probably still don’t but used the default.

Moving to the XT3 and 4K, I went -3.

Panny S5 and S1H, I think I am at -4 but am away right now on vacation so can’t check.

Zero sharpening in post but used to use unsharp masking for 1080 as I found it a little soft.

Might have a play when I get back myself but otherwise pretty much there with my ‘look’ based on the combo of; tweaked Natural profile, specific Sigma lenses and focal lengths, 1/8th mist filter, zero grade as such in post other than some basic stuff and then a single ‘like analogue film’ finish I had Aditya Varma make for me as a one off.

Sharpening and skin tones are the only areas where I could maybe improve even further.

Anyway, interested to see what you do @kye

 

[kye]

I've gone through and reviewed the shots I pulled from my back catalog and got some interesting results.

Let's start with the GH5 in UHD 24p, on a 1080p timeline.  

(In order to sharpen you have to have something to work with, so I'll be talking about how good the codec is, you'll see why later on...)

Take a shot like this, SOOC:

Apply a CST and maybe some level adjustments if it needs it, and we get:

and this is what the analysis looks like:

This looks very similar to what we saw from the streamed reference images.  The stubble but softened light gives a bit of green but not a strong amount.

We can apply some sharpening and get this:

and a 100% crop of the 1080p timeline:

But that's in relatively good lighting conditions, how about under tricky situations?

This is an image of dark skin tones, on a boat with no lighting on a river perhaps 50-70m from shore where the floodlights are lighting up the festivities.  It was taken with the Voigtlander 17.5mm wide open (these lenses are known for being soft wide open) and the GH5 in auto-ISO mode, so who knows what the ISO was...  

This was my first trip with the GH5 and the Voigtlander and I had no idea what I was doing, and if memory serves, I think I was exposing to protect the highlights in the background!!

Image SOOC:

The standard CST does this, which is radically underexposed:

But if we apply a ridiculous exposure adjustment we get this, which doesn't look good but will serve our purposes to look at sharpening:

and this is the analysis:

Note the green areas on the face are not just random noise - there is detail there.  I reviewed successive frames and it is indeed detail.

This is a 100% crop without any sharpening, just so you can see what detail is there:

and with the sharpening I applied before, we get:

It's worth pointing out at this point that these are from the 150Mbps Long-GOP UHD mode, not the 400Mbps ALL-I one.

The GH5 earns its reputation once again.

Now, let's change gear and talk about the XC10.  Remember I said that we'd be talking about codecs for a reason?  Well......

 

[kye]

The XC10 - the bane of my introduction to colour grading.  I could never get the footage to look good, and now I finally realise why.  

Long story short, it's a cinema camera with a slow zoom lens, so you have to use it fully-manual, and I didn't.  What that means is that if you put a scene in front of it that is within a few stops of correct exposure then it will look fine, but if not then it will either drown the image in ISO noise, or will hit its fastest shutter-speed (which being a cine camera isn't that fast) and will then stop down the lens, which was slow to begin with, and introduce diffraction.

These are why most of the images I have from it look like poor quality JPG images, and sharpening them just makes them look awful, not sharper.

OK, I'll move past that and let's move on to what it looks like from the few shots I have that look good.....

This is a test shot from when I first got the camera, it's SOOC so I suspect it's a 709 profile:

and here's the analysis:

Seems reasonable.

What about C-Log?  This is SOOC:

As usual, the CST created a neon abstract painting out of the skin tones, but with saturation at 60%, we get something reasonable:

and the analysis:

All good too. Soft skin, but close-up and with direct sunlight, gives some green.

<long sections complaining about the camera deleted lol>