Over at our sister blog petertellone.com, our friend Irving (Yechiel) asked; “What is the difference between a blend and an HDR???” So I thought I would take that opportunity to talk about what blends are and how you can use them and how they relate to HDRs.
First off I would like to dedicate this post to our friend and Photographer Hikin Mike. Mike is a guy that has had some adversity in his life but hasn’t let that stand in his way of doing what he loves. And that is taking photographs in his beautiful area of Northern California including and encompassing the area around Yosemite National Park ( insert jelousy smiley here). Now it isn’t a secret that Mike isn’t a fan of HDR, he instead prefers to do Blends and quite well I may add. But in the end they both are a way to extend dynamic range and really that’s what we want to do and sometimes they do have some benefits over traditional HDRs. Mike is the blending champ so this post is for him.
As I just talked about, our real purpose in all of this is to extend the Dynamic Range that is usable in our Images. Traditionally we may have used a Split or Graduated Neutral Density Filter. These filters allow for a 1-3 stop difference in exposure between the top and the bottom of the filter, allowing you to have a say a darker exposure for the sky than the land beneath. Unfortunately the problem with them is that the transition is a straight line. Great when say you are shooting the ocean with its flat and level horizon. But what if you had a more complicated scene such as a mountain range or shooting through a window to the outdoors… Enter the Blend.
What is a Blend?
A blend is taking 2 or more images and placing them on top of each other and then, through the use of layer masks, revealing parts of each image that have an exposure that is correct for that part of the scene. In essence what you have is a Hand Made HDR. Instead of a software program doing the tone mapping and deciding the tone values for different parts of the scene, you are doing this by hand.
The downside of this is it can be, but most certainly isn’t always, a very time consuming method. But it really depends what you want to do, if it is just blending two values Sky/Earth it can go quite quickly. But if you want to bring out the subtle tonal variation that an HDR has it may take you quite some time.
There are some advantages also, it can be more of a traditional photographic look than HDR can be sometimes…well unless you follow my methods ;), and it can be very good at doing one thing that it seems most HDR p5rograms have a difficult time with and that is handling large areas of white. Scenes that have large areas of white often get turned gray by HDR programs and this is one area that you can get better with a blend than an HDR.
And the fact is, There have been times that I have made and HDR and then used a blend afterwards to bring back detail or the above white areas into an HDR. One of the very cool things about Photomatix 4.1, the latest version, is that in the tone mapping panel you can select areas and replace them with a single exposure. In essence you are both tone mapping and blending at the same time. This is really a great feature. But as I said in the review of that product, there are times I like to have more control over it and do it in post in another application like Photoshop.
So enough talk, let’s actually go through the steps of blending images
Blends in Photoshop
The first thing you need to do is shoot FOR a blend. You may shoot just like you normally do for HDR and use those images. But most people that do blends do so with two images, one exposed for the sky (Highlights), one exposed for the ground (Midtones). The midtone exposure usually has enough latitude to have detail in the shadow area and we are most concerned about not having blowout in the Highlight exposure.
One you have your exposures, open the files you want into Photoshop, You can use, RAW, Tiff, PSD or JPEG images and you can also make adjustments to each of the images if you desire before the blend but you must keep in mind the final product you are going for after the blend that you don’t mess up things for the final product.
In this instance I am going to take two images (exposures) that I shot this past Sunday and use those for this example. Plus I also shot an HDR right afterwards so we can compare. I like using RAW files so I opened the two images in Adobe Camera RAW without making any adjustments to them because they were shot pretty well in Camera. Clicking select all and Open, I opened both images in Photoshop.
Here are the two file we will be working with
I shot two images; both at f/22, ISO 100 with a 3 stop ND filter on to silken the water. The images were shot 45 minutes after sunset so that the dynamic range was wide but not wide enough not to be able to capture in two shots. The exposure times were 1 and 4 seconds respectively
I think it is worth mentioning that an advantage of a blend here over an HDR will be in detail in the clouds. In the subsequent HDR, we have three long exposures of 1, 4 and 15 Seconds. Over that entire time periods the clouds move quite a bit and lead to blurring in the final image. We don’t have that problem with a blend since we only are going to use the 1 second exposure for the sky.
Once we have our two images open we select our Move tool from the toolbar. Holding down the shift key (which allows for perfect alignment of the two images) we drag one image on top of the other. The order really doesn’t matter but we may want the one image that we will use the largest area of on top.
Now that we have the two layers together, we click on the top layer in the layers panel and then go to the bottom of the panel and click add layer mask.
With the layer mask in place on the top layer, I will select a large soft Brush and the color black to reveal the layer below for the sky (Black to reveal, white to conceal, X to switch between them) And begin painting over the sky area to reveal the darker and better exposure of the image below. I use a soft edge brush so that there isn’t a hard transition between the two images but there are times when you may need to use a harder edge brush in smaller detailed areas.
I turned on the quick mask to show you the area I painted over. The result is this:
This is a good first start, but I want to further refine the transition between the two exposures so I will switch my brush color to dark neutral gray. You can do the same thing by keeping the brush black but change the opacity and fill of the brush, but I prefer using different shades of gray between white and black and not change the brush itself.
Using a medium gray brush I work on the transition area of the water in the distance and the trees on the left. I went back and forth until I got the overall image with the balance I wanted.
At this point I added a levels adjustment layer and adjusted the image as a whole, and even on that adjustment layer, used the mask to take away a little brightness in the body of water behind the rocks.
And then as my final steps I will go in to the different layers and dodge and burn certain areas to just get the balance I want as I showed in this Local Adjustment tutorial, and then finally I added a high pass sharpening layer over the whole image.
This is the final finished image.
In comparison here is an HDR shot just minutes later. They are different, both are nice.
The HDR has a little better detail and range of tones in some of the smaller areas, The Blend actually gets the sky better and the water swirl better because they are just one image and not subject to some of the blurring that takes place when three images are combined in the merge tone mapping of HDR.
And like I said, there are times I will do an HDR and then blend in a part of the image I want to get even better
Hope that helps,