Blownout Highlights

Blownout Highlights

In this video I go over a number of my favorite ways of dealing with highlights that are lost and cannot be recovered. I don't go all the way through an edit, but just concentrate on the specific techniques associated with the lost data.

If you'd like to follow along, some of the original files are here and here

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Hi everybody.

Harry with another Darktable screencast.

Today I'm going to be working on blown-out highlights and how to recover them.

I have six different examples here.

I'm going to be using different techniques and showing you my favorite ways of recovering a photo when the highlight is completely blown out and you have no information.

Let's start with this one.

This is a sunrise scene.

I'll turn up the exposure so you can see what we're looking at.

Cows, and a wall, and the sunrise.

This is in northern England, near the border with Scotland.

I'm going to zoom all the way in.

If you hold down the Control key and use the mouse wheel, you can zoom in even further, all the way to 200%.

First thing I'd like to talk about is fringing.

There are a couple of things that I'd like to show you about fringing.

One: be careful of Chromatic Aberration corrections when you're looking at the sun going around an object like a cloud, a tree, a powerline...

You'll get these color fringes here, and if you turn on the correction for Chromatic Aberrations, it can sometimes exacerbate the problem.

I'll take a snapshot, and then I can move this back and forth.

We can look at the difference.

I'll turn on the correction for Chromatic Aberrations.

Now, see, this: we've got cyan and magenta fringing here.

It's gotten way worse.

Without it, and with it.

So, be careful; don't use that without checking first.

Since we're talking about fringing, let's look at the Defringe Module.

The Defringe Module has a default setting that's very useful: the Global Average.

But there are some differences between that and the Local Average.

I'll show you that in just a second.

First, let's turn on the Defringe Module with the Default Settings.

You can see that it has some effect.

For instance, look in this area.

It makes the transition a little smoother.

Over here, it doesn't do much correction.

I can adjust the range of the correction by increasing this Edge Detection Radius.

If I turn it up a little bit I get a little smoother edges.

See how the effect goes all the way into this area here? If I turn down my Threshold, it will include areas for correction that weren't part of the correction before.

But now I'm getting some color cast that I don't want.

A little bit of cyan is showing up in here.

Same thing here: we've got the correct color, but with the Defringing, we've had a color shift.

Now we've got a little bit of cyan.

Let's look at Local Average.

With Local Average I've got the right color.

Bring up our Threshold a little bit, bring down our Edge Detection Radius a little bit.

On the left side is no correction, and on the right side is some correction.

We've gotten rid of some of this fringing here, a little bit over here, down in here a little bit, filled in this area.

All in all, it's an improvement: not a vast improvement, but it's certainly an improvement.

This looks like a problem right in here.

What can I do about that? Well, maybe if I turn up my Threshold so it doesn't include that area...

There we go.

That's the Defringe Module.

This isn't a perfect example of where you'd use it, but it gives you a general idea.

Now, let's talk about this area in here, where it's white.

For instance, if I use my Color Picker tool, and my Eyedropper, and convert the display to RGB instead of LAB, you'll see that in the middle here, I've got nothing: 255 in all channels, no information at all.

What can I do about that? Well, there's a wonderful tool that's been included with Darktable recently called Color Reconstruction.

What this tool does is it looks at adjacent cells, sees what their hue is, and then fills in the blown-out area with the correct hue.

Now you say,"How does it know which color to choose?" Does it choose this color? Does it choose this color? THAT is adjusted by looking at this Spatial Extent.

That tells it how far out to look for the right color.

Do I look right next to the blown-out area, or do I look a little bit farther out? We'll turn that on, and you see that, by the Default Settings, it came up with this hue and filled it in.

If I use my Range Extent and pull it out so that it's looking farther physically, it gets more red.

That's because it's starting to look at this area.

If I pull it in really far, then you'll see it's starting to use the white to fill it in.

If I want the yellow, I can go out a certain distance by slowly moving the Spatial Extent until I get the hue I want.

Now, in this particular instance, I don't want to have it all be the same color.

I'd like for it to still look like the sun is here.

I'm going to do that by applying this effect with a Drawn Mask.

I'll use a Circle Tool and put a circle right where the sun is.

I can tell where the sun is by looking at these rays.

They're going to converge right in the center.

There we are.

Now, let's make our circle smaller using the Mouse Wheel, so that it's approximately the size of the sun, maybe a little bit smaller.

Then I can extend this area of blend by moving the Mouse into this area and using the Mouse Wheel to extend it.

This is the reverse of what we want.

I'm going to use the Minus here to toggle the polarity of the Drawn Mask.

Now we've got the effect, but less of the effect in the middle.

Make the sun a little bit smaller, bring in this a little bit.

There we go.

Now we have our sun where we want it, but the sun is all white.

We don't want the sun to be white; we wanted that nice yellow.

What I'm going to do is I'm going to take all these settings that we used, so we have the same color, same hue: everything.

I am going to Duplicate Instance.

When I do so, I have exactly the same effect I had before.

This time, I'm going to remove the Drawn Mask and change it to Uniform.

So, it's filled in the whole thing.

I can change the Opacity.

Now, that instance combined with the previous instance gives me a nice, smooth transition to the right hue but a lighter version of it.

We'll zoom out and see how that looks.

There we go.

Okay, let's go on to the next one.

Here's another example.

We'll be using Color Reconstruction here also.

Once again, I zoom in, see what I can do with the fringing a little bit.

You're not always going to be able to get excellent results.

It's worth a shot, though.

Usually, you get some improvement.

I've got a little bit of cyan in the middle and over here.

Bring my Threshold down to include those areas.

That's probably about as good as I'm going to do.

Over here at Color Reconstruction, I'll turn that on.

It's grabbing this yellow.

I can adjust which color it's looking for with this tool.

If I bring it down too far, it's looking at these colors close to it.

If I bring it up further, it's looking for colors farther away.

If I bring it up really far, it's looking at these redder colors over here.

Once again, I want to be able to see that there's a sun and not just have it be a large blob.

I will apply this with a Drawn Mask.

Circle for the sun, a little bit smaller, a little bit larger.

Fade, Reverse.

There we are.

Duplicate the instance.

Change it from Drawn Mask to Uniform.

Turn down the Opacity.

I've got a little bit of banding here.

This is a little tricky to get rid of, so I'm going to use a Gaussian Blur, and I'll paint it on.

Indicator.

Blur that Mask.

Increase my Radius.

There we go: nice and smooth.

There we are.

Next one.

On this one, we have a different problem.

If I use the Color Reconstruction, I'll be pulling colors from these edges, and they'll be green.

I don't want the sun to be green; I'd like the sun to be yellow.

I could just paint the middle with yellow, but if I do that, then, off to the sides, the whole thing will be the same color.

I'd like for it to go from yellow to the color of the sky, which is a little bit blue with red in it.

For this instance, I'm going to use Split Toning.

I'll apply the Split Toning with a Parametric Mask.

Let's turn on Split Toning.

Sky, being a little bit blue, I will bring this over to my sky color.

For the sun, I'll find a nice sun color.

a little bit warm, that's nice.

I have a Color Balance here, and I have a Compression.

The Compression tells me, where does it divide the line between the blue and the yellow: how sharp of a dividing line is that? And the Balance says, do I want more yellow or more blue? First off, we don't want to apply the Split Toning to the whole image; we just want to apply it to these bright parts that are blown out.

We're going to use a Parametric Mask for that.

Look at the L Channel.

Turn on the Mask Indicator and turn the sliders until we find the area that we want to isolate.

Now, I'm going to slide out a little bit here so it's got a nice, smooth effect.

I'd like more saturation for the sun.

I'd like it to fade to blue a little bit faster, so I'm going to move my Balance a little bit, turn up my Compression.

Before, and then after.

I'd like more effect, but I'm already maxed out on my Saturation, so I'm just going to Duplicate the instance.

Don't forget to turn it on.

Before, and after.

There we go.

Here's another one.

We have a waterfall.

The waterfall, we're not going to be able to do anything about it; it's blown out in here -- except, it's not all the way blown out; we have a color cast.

I'll show you.

Turn on my Eyedropper Tool.

Go to RGB.

When I look here, I see that it's green.

My Red and my Blue are blown out, but I have Green.

Well, I don't want that; I want it to be white.

How am I going to do that? With the Monochrome Tool.

I go to Color, enable Monochrome.

Now, if I turn this on, it makes everything white, well grayscale.

But now we have nice and white in the waterfall.

See? My values are equal.

But, I don't want to apply that to the entire image.

Once again, I'm going to use a Luminosity Mask.

Turn on the Mask Indicator, turn up my sliders to isolate the areas I want.

I can feather them.

Turn off my Mask Indicator.

Now I have white in these areas.

My values are all equal.

No more color cast in my blown-out areas.

Another one.

This is blown out in here, but once again we have a cast.

Well, we'd like it to be a little bit blue, and right now we've got the wrong color absolutely.

We'll bring down our Tone a little bit so that we've got some opportunity to apply color in there.

In this instance, I'm going to use the Color Channel Mixer and select Hue.

Then I'll come up with the color I want.

I want just a little bit of Red and mostly Blue.

I'll grab an area.

Eyedropper Tool.

Grab an area.

Put it under Live Samples so I can watch.

Once again, A Channel is Green for cooler colors and warmer is Magenta.

Well, we don't want green skies, so I'm going to bring down the Green a little bit.

Now we've got Magenta, and this is warm, so this would be Yellow.

We want it to be a little bit blue, so I'm going to bring up my Blue a little bit.

Now we have a little bit of red and more blue.

I will apply that with a Parametric Mask, once again isolating the blown-out areas with an L Channel.

Pull my sliders over to find the area I want.

I'm going to use Mask Blur this time to give me a little bit smoother transition, and I can change my Opacity for how much of the effect I want.

Before, and after.

It's still blown out, but we have the right color.

We can do other things with it later on to help with that.

Last instance.

In this one, there's not much I can do at all.

I've got color casts surrounding these blown-out areas in the sky.

If I look for adjacent colors, they're going to be neutral because these are grey.

There's magenta here; there's cyan here.

This is terrible.There's only one fix for this, in my opinion, and that's the Spot Removal Tool.

I'm going to grab clouds from another area and put them in this area.

Let's do it.

Spot Removal.

Select the area around the cloud.

Set the Transition Zone to a larger, nice smooth transition by using the Mouse Wheel to make it larger.

Then grab my sample area and move it around until I get the effect I want.

Now, you always have to be careful with things that fade into the horizon that you pick the approximate same size of detail.

If I go way down here, then I've got these fine details surrounded by these large details, so I want the same coarseness.

I also want the same lightness approximately.

Well, let's see what that looks like.

That's quite believable.Let's look at this area down here.

This is a little different; I've got a building in the way.

Let's see how we fix that.

Once again, go to the Spot Removal Tool.

I don't want to use the same settings as my previous Spot Removal Tool, so I'm going to create another instance.

I'll show you why in just a second.

Select the area that's blown out.

I'm going to zoom out and find a nice cloud to put there.

Once again, I'm looking for approximately the same size of detail.

That looks pretty good.

What do we do about the building? We can use a Parametric Mask.

I will apply the Spot Removal with a Parametric Mask, once again going to the L Channel.

I'll pull up these until it excludes the building and the little post here.

I've got a little bit of an uncomfortable transition, so I'm going to take my Mask Blur and increase that to about 1 pixel.

Let's see what we've got.

There we are.

That was a quickie today.

I hope you enjoyed it.

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