Published on 26th January 2014
HDR Landscapes 2 - Basic Blending
This series of tutorials has come a long way, to put it lightly. Ever since I first encountered Tony Kuyper's tutorials on luminosity masks people made it apparent to me that I understand it better than most. I'm certainly no prodigy and there are hundreds of other photographers who understand it as well and better than I do, but everyone isn't willing to share. My first photography workshop was organized by other people so that I can try to give them an introduction to this amazing technique for combining and editing landscape photos. A few years later I did a series of free tutorials on my website and up until today it is still the backbone of good traffic to my site. I have however been wanting to update them as the gap has grown significantly between what those tutorials teach and what I know. I also think that after about 50 workshops I have a much better understanding of how to teach and what the problems are that people get stuck on. What I attempt to do in these new tutorials is to give you an understanding of HDR instead of giving you a list of steps to follow. This is the first of a few and if you can grasp what I explain in this one then you should be fine with the ones to follow. One of the biggest problems are that people don't always have the ideal images to practice on, then it feels like they're getting nowhere so they just give up. While the tutorial is free, I now offer you the opportunity to buy a set of ideal images to practice on for only $5. Please click here to continue to the products page.
Before you start, please read the following tutorial. This one builds on the primary exposure system explained in the previous tutorial.
There is a lot of confusion about what exactly it means when you say an image is ‘HDR’. As I explained in the first article, it’s an image that is made up of differently exposed, but otherwise identical images. Because the images are differently exposed they collectively contain a much higher dynamic range than the camera can capture in a single exposure. When combined, the images create a single High-Dynamic-Range photo. How you combine the images should be irrelevant to the title there-of, but that is not the case for lingo in the photographic community.
‘HDR’ has become the word associated with software that automatically combines the different exposures. The best-known example is of course Photomatix and as with anything in life, the easiest route doesn’t produce the best results. Photomatix has improved a lot over the years, but its results are still far from what can be achieved if doing things manually.
‘Blending’ or ‘Luminosity Blending’ has become the term associated with manually combining the images and that is what I will attempt to teach you. The most important thing you need to know is that the theory may be simple, but the practice isn’t. There’s no step-by-step guide that can solve any problem, you simply have to experiment and learn from the experience. Every single image (or sequence of images) you blend will be different and will teach you new things. Some clouds, trees and colours just blend better than others. I have HDR sequences in my Archives of amazing scenes with amazing light, but I’ve just never been successful at blending them together. The good news is that with experience you will improve and as long as you captured all the tones in the scene you can go back to the image at any stage in the future. The two images below show an automated HDR and a manually blended HDR. You can guess which is which.
The greatest mistake that people make is to think that HDR is some sort of wonder drug that makes bad photos good and good photos amazing. If you are one of those people then you need to change your mindset very quickly. If you don’t then you’ll be swearing behind the computer because your photography isn’t improving when you should be out in the landscape with your camera. HDR is simply a solution to a limitation of the camera; it is not a way of taking better photos. Yes, good editing skills are necessary, but there is much more to be learnt in the field than behind the computer. Strong composition and good light are what make amazing photos, not HDR skills.
So if you have a bracketed sequence of a scenic landscape in good light, then you’re ready to learn blending. If not, you can purchase my one of my example image packs to practice on.
The first concept you have to familiarize yourself with is layers. It’s Photoshop’s secret to success and probably the most powerful tool in its arsenal. The layers function allows you to stack any number of images on each other like sheets of paper. You can then combine select areas of each layer to create a final image and you can apply an endless amount of effects to select areas in select layers. This probably just sounds confusing, but once you apply it you'll see what makes it so brilliant.
Your workspace (layout of palettes and toolbars in PS) should have the channels and layers palettes readily available and the histogram clearly visible. Below is what my workspace looks like for blending.
The first step is to stack the images on top of each other as layers. As with most things in PS, there are many different ways of doing this. The easiest method is directly from Bridge or Lightroom.
LIGHTROOM – While in grid or loupe view, simply right-click on any of the selected images, go to edit and then at the bottom you will see ‘Open as Layers in Photoshop…’ Click that and Photoshop will load them as a layer stack. (As in the image below)
BRIDGE – Go to Tools > Photoshop > Load files into Photoshop Layers…
PHOTOSHOP - You can also manually stack the images once they are all in Photoshop as individual images, but it’s a lot more effort. For the sake of those who don’t have Bridge or LR, I’ll explain how. In order to stack all the images, you have to be able to see them all within PS. If you open multiple images, PS will put them all in tabs within the program and you'll only be looking at the top one. Please don't mistake the main Photoshop window for the image tabs. The red, yellow and green buttons are the main PS window and the multiple tabs with image names are the image windows.
Go to Window > Arrange > Tile All Vertically. This will put all the open images in tabs next to each other.
Now select the move tool (V), decide which image you want at the bottom and simply drag the others onto that one. There are four things you need to keep in mind when stacking manually.
- The images need to be stacked in order. Whether you stack them with the brightest one at the bottom or the darkest one at the bottom doesn’t really matter for now.
- To drag an image, it first has to be selected. When doing blending you'll be switching between various images and layers all the time and it will cause a lot of confusion when you're trying to do something and Photoshop isn't responding as it should. Make a habit of always clicking on an image/layer once before you want to do anything with it.
- If you drag and drop one image onto another, it will just be dropped in where ever you release the mouse button. You’ll then have to align it in the frame afterwards, which is unnecessary effort. You can simply hold shift while clicking and dragging it over and it will snap perfectly in place.
- Once an image has been dragged into the stack, you can close that image. That tab will have to be selected first, so the habit of clicking on an image once before doing anything with it helps.
Once your images are stacked, your layers palette should look something like the image below. For those who have been wondering – any and all RAW changes should be made before stacking. You can make different RAW changes to the images in your sequences, as long as they still fit on each other perfectly. So remember that if you crop or do lens corrections to do it on all of the images in the sequence.
I used to stack my images from dark to bright (dark at the bottom), but Lightroom and Bridge’s auto-stack feature does it the other way around. Neither is better than the other, but I've found that being able to work both ways around gives one a greater understanding of blending. To start simple I’ll do a blend of only two images, stacked with the darker image at the bottom.
This is the very common p+h1 situation where you have a primary exposure with blown highlights and a secondary highlight exposure that contains those highlights. In this sequence the highlight exposure also has a slightly blown area where the sun is about to pop out, but that highlight is practically unrecoverable. I have stacked the primary exposure on top of the highlight exposure, so the detail for the sky is in the layer below, the question is now simply how do you bring it through to the top one? It's very simple - take the eraser tool (E) and erase a hole in the top layer. The result should look something like my image below.
Please refer to to HDR landscapes 1 if you don't understand what p+h1 means.
If you hide the bottom layer by clicking the little eye to the left of it in the layers palette, you should see a checkered background where you erased. That means that there is no more data there. This is the first of two problems when using the eraser tool, you are throwing valuable data away. You can hit undo or just go back in the history palette, but only for so many steps. There is a solution that provides the same effect as the eraser tool, but in a non-destructive way.
The Layer Mask
Without their masks, layers wouldn’t be that great. The concept can be a little confusing at first, but you'll never regret the effort of learning it. The simplest explanation of what a layer mask does is it controls the transparency of a layer. You can also control the transparency of the layer by using the opacity slider in the top right corner of the layers palette, but that is a universal control. If you slide down the opacity of a layer then the effect will be applied to the whole layer. A mask can give you amazing localized control of a layer's transparency. The golden rule for masks is the following.
Black Reveals, White Conceals.
If a layer's mask is white then it will conceal what is below the layer. If a layer's mask is black then it will reveal what is below the layer.
To add a mask to a layer, simply click on the little rectangle with the circle in that you will find at the bottom of the layers palette. Always make sure that you’re adding the mask to the correct layer by just clicking once on your chosen layer in the layers palette.
As you will see when clicking the button, a white mask appears next to your chosen layer and because it conceals everything below the layer, nothing has happened to the image you are looking at. If you hold down ALT while clicking the add layer mask button, it will add a black mask to your chosen layer. This will reveal everything below the layer. I won't touch on black masks in this tutorial, but it will become a crucial part of the workflow in the next one.
Rookie Mistake #1 - Using the Wrong Brush Colour
Now that you know how to add a white or black mask to a layer, we can get back to why a layer mask solves the eraser’s destruction. If your two layers are stacked and you’ve added a white mask to it then select the brush tool, for which the shortcut is B. Your brush colour should always be the opposite of your mask colour, so if you have a white mask then make sure that your brush is black. Two very handy shortcuts are D and X. If you press D it will set the brush colours back to their default, which is black on white. If you press X it will swop the brush colours regardless of what they are.
Once your brush is set to black, you can do exactly the same as you did with the eraser. Just drag any brush stroke through the image and it will reveal what is in the layer below. Where the eraser was making a hole in the actual image, you are now simply creating a hole in the mask by painting black into it. If you hold ALT while clicking on the mask (the mask in the layer palette) then it will show you the mask as in the image below. To get rid of it just ALT+Click again.
Exactly as with the eraser tool, if you don’t like what you did you can just go back using the history, but that is again limited to only a certain number of steps. The magic of a layer mask is that if you don’t like what you did, you can undo it by simply painting white over the black again. The black brush revealed the layer below and the white brush can conceal it again. Instead of erasing data from the images, you are now simply painting in the mask. This solves problem number one of the eraser's destruction.
Problem number two is getting an even transition between two layers. Even if you're using a drawing tablet, a brush remains a relatively sloppy tool. You can do your best to blend two images together using the brush without leaving any evidence of HDR, but there are better ways. Fortunately there's a very simple solution; the gradient tool.
If your layers are stacked and you've added a mask, you can select the gradient tool from the toolbar or hit G to select it. It shares it's spot in the toolbar with the paintbucket, so if you've ever used that you'll have to right-click on the paint bucket and select the gradient tool. Hit D to make sure your colours are black on white. Before I start explaining, take the tool and click a short distance above the horizon. Now drag the mouse perpendicularly down across the horizon to the same distance below and release the button. Below are three images, the first showing how I dragged my gradient. The second shows the effect it has had on the image and the 3rd shows the gradient that has been created on the mask.
I've always hesitated whether I should explain what the gradient tool does technically in context of the whole mask and 'black reveals, white conceals' rule. I think it is often more confusing than if people just play with it to see it's effect. Luckily a lot of people are much more familiar with the gradient tool since Adobe introduced it to the RAW editor. The one in Photoshop is the stoneage version of the one you find in Lightroom and ACR so if you can operate that one, you'll be fine with this one.
As you can see in the last image, the gradient does the following; From the top of the frame to where I clicked it created solid black on the mask, thus revealing everything from the layer below. From where I clicked and dragged to where I released, it created a perfectly linear black to white transition. This ensures that you're getting the smoothest possible transition between your two layers. From where I released to the bottom of the frame it created solid white, which conceals the layer below and thus has no effect on the top layer.
While the gradient is a very simple tool, it is a very versatile one with a lot of variables. It doesn't have to be dragged from top to bottom and it doesn't have to be dragged straight down. It can be dragged in any direction, for any distance. The shorter the distance, the 'harder' the transition between the two layers. The longer the distance, the 'softer' the transition. For each image it's different and only experience will teach you what the ideal is. Below are a few tips for using the gradient tool.
- Drag perpendicular to the horizon - If the horizon is slanted then your gradient shouldn't go straight down. Keep it 90 degrees to the horizon.
- Drag drag drag - If you don't like the gradient you dragged, just drag again. A mask can only ever have one gradient applied to it so you don't have to undo your step to drag again.
- Experiment - Never drag the gradient only once and allow yourself to be satisfied with it. Start with a short/hard gradient and drag softer and softer until you're happy.
- Hold Shift - If you hold down shift while dragging, the tool will snap to the nearest 8-way axis.
The gradient tool solves the even transition problem, but it is still limited to the same situations as graduated filters. As soon as something protrudes above or below the horizon, you've got problems. That is where luminosity selections come in handy. You can't continue if you don't know how to get highlight and shadow selections, as explained in the contrast tutorial. Luminosity selections and masks are major challenges for people that are unfamiliar with it, so I've split it into separate tutorials to try and make things easier. Refresh your mind on luminosity selections as the next part of the tutorial will be available in a few days!