What is HDR and why it’s used?

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Even after years of it’s being used, HDR is still not properly known and understood between photographers. So to make it at least easier for some of you, in this post I will be going exactly what it is and why it is used. I will also go through few additional questions, that are close to the subject.

I will avoid being too technical, and try to explain things as simple as possible.

What is HDR?

HDR stands for Hight Dynamic Range. It’s used to describe photos, where different techniques have been used, to expand the dynamic range ,to cover the whole available range of the scene.

For instance in photos like these two:

Foreground would be black without HDR
The sky would be white without HDR

What is Dynamic range?

In simplest terms, the dynamic range is the difference between the brightest and the darkest point. In a scene, it’s the difference between the brightest light and the darkest shadow. In a camera, it the difference it can capture in a single photo.

When you look at something, your eye moves rapidly, and adopts to all light sources very quickly. Like that you can see a very high dynamic range, as you don’t see it all at once. In comparison, a camera has to get the whole range in one shot.

What is DRI and EDR?

DRI stands for Dynamic Range Increase and EDR stands for Extended Dynamic Range. Both have the same goal than HDR to increase the dynamic range of a photo, but the names are commonly used when using different techniques than tone-mapping software. Mostly when using luminance masks, one talks about DRI or EDR.

Why is HDR used?

Again, in simplest terms, it’s because a camera cannot capture the whole dynamic range of a scene in one photo. But to get a better understanding, let’s look at an example.

Here are two photos from scenes with different dynamic ranges. The first one has a very small dynamic range (the difference between the dark and bright spot is very small), the second one has a big dynamic range (the difference is huge).

Scene with a small dynamic range
Scene with a big dynamic range

 
To visualize this, lets look at the dynamic ranges as bars, going from the darkest to brightest point. The sizes are just as illustration, so the proportions are not exact.

Like this you can visualize, what everything one needs to capture in a photo. As the one with the small difference is easy to capture in one photo, lets continue only with the second one.

Now let’s compares what we get when capturing the scene with a dynamic range of a 8-bit jpeg and with a RAW file, which is usually 14-bit. You can see, that the dynamic range of the scene can be much bigger. Even with the bigger range of the RAW, you loose a lot of information. Everything that is cut off, on the sides, turns to complete black or white.

If we looked at a JPEG photo and a RAW photo in comparison, it looks like this (the dark parts in the RAW photo have been brightened, the bright parts darkened, so it can be shown on an 8-bit screen)

JPEG photo
RAW photo

 
So how to capture the whole dynamic range of a scene? This is where bracketing comes in. One takes multiple exposures, each one capturing a part of the full scene. It can be visualized like this:

 
The brackets are overlapping, and each one covers a different part of the dynamic range of the scene. It can even extend more, but that parts will contain no information.

These photos can then be put together into a 32-bit HDR file, that can contain this whole range at once. This file is used only as a step in photo editing, as it can’t be correctly displayed on a screen. It’s mostly used only in 3D modeling.

What can be normally shown on a screen is a 8-bit file (there are 16-bit screens, but there are not commonly used). Most JPG files are 8-bit. So what is needed, is to use a any of the available techniques, to compress the dynamic range in the 32-bit file, until it fits into a 8-bit one (or a 16-bit one as a middle step). This can be visualized as this:

So what is used to do this? Any number of techniques. Manual blending, HDR tonemapping, just brightening the dark parts and darkening the bright parts and many more. Once this is finished, the dynamic range in the photo is the same of the one that can be shown on a screen.

The goal of all this is to get from a scene with a very high dynamic range, to a photo that can be shown on a normal screen.

Scene with a big dynamic range
Final HDR with few additional edits

Is this the same HDR as available in most phones and modern cameras?

Well, yes it is. All the cameras take multiple exposures, to get the whole dynamic range, and combine them into one shot. Especially mobile phone cameras have a horrible dynamic range, and this can help a lot. Of course the biggest difference between this and doing this on your own, is that this process is fully automated and you have very little or no control of it.

What is HDR look/style?

HDR look, or we can also call it HDR style, is a certain look of a photo, that is quite often mistaken for HDR. It’s usually characterized by very saturated color and very strongly defined details, so called grunge look. But don’t be mistaken. This looks has nothing to do with the photo being a High dynamic range image. It can be done with any image, and is often just created using post-processing filters like Color Efex or Topaz Adjust.

 
It depends all on the photographer, if he wants to go with his editing style into this area or wants to go more towards realistic results.

Here are two of my photos, one with a more stylized HDR style, one with a more natural style. Both are HDRs, and as you can see, the final look has almost nothing to do with it. It’s all depended on the style one wants to create.

More stylized HDR style
More natural HDR style

 
And that’s all for this post. Feel free to ask if you have any questions, and to find out more how to create HDR photos, check out my HDR tutorial and my video tutorial series Master Exposure Blending.

As every Monday, it’s time for a new Before/After processing post. For today I chosen a little more compolicated photo to show you, so this post will include a lot of images. So let’s get started :)

First let’s take a loot at the final photo and the 0Ev raw file I started with. Today it’s a photo of the Dubai fountain.

Dresden
Dubai Fountain

 
As you can see, in the original 0EV there was no fountain. That’s because I taken a separate series of 6 exposures, when the fountain was off, to get the background, and then a long series of shots exposed for the fountain, to blend in. So here you can see the 6 exposures, and the huge amount of the fountain shots.

Dresden
Dubai Fountain

 
From the 6 exposures, I created a HDR in Oloneo photoengine, as my base. I then selected three additional photos, two for the fountain, and one for the people in the foreground. You can see on the photos, that I tweaked them in Lightroom, so they better fit into the Oloneo Photoengine result.

Dresden
Dubai Fountain
Dubai Fountain

 
And here you can see which parts from those photo I ended up using. This are the layers from the final HDR, numbers 4, 5 and 6 in the list bellow. Btw, you probably noticed, that there are nice shots of the fountain I haven’t used, but they are planed for another edit of this photo :)

Dresden
Dubai Fountain
Dubai Fountain

 
So I loaded all the original exposures, the Oloneo Photoengine result and the three additional photos into Photoshop layers, and continued with following edits (numbered from bottom up):

1. Olone Photoengine result
2. -2EV to darken few bright light in the distance
3. 0EV to correct a little ghosting in few trees
4+5+6. Blended in parts of the fountain and the people in the foreground (as seen in the screenshots above)
7. Noise reduction for the whole photo except for the sky, so no color banding is created.
8+9. Added contrast to the whole photo.
10. Color balance to give the photo a little more cooler, bluish look.
11+12. Added glow (check out my tutorial on this)
13. Brightened the dark areas, as they got too dark after the glow was added (check out my video on this)
14. Removed few unwanted objects in the foreground.
Dubai Fountain

And that’s all I did with this image. To find out more on how I edit, check out the guides and before after categories on this blog, or check out my video tutorial series here:
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The bastion stairs

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Behind the scenesContinuing with the Budapest theme, as that’s the only place I took photos in the last month :). Today, it’s a shot of the stairs leading up to the Fisherman’s bastion. I actually tried this shot a year ago, but was not happy with the result. So I tried it again this time, and I’m still not sure if I’m happy with the result, but it’s much better that last time :). It was of course taken early in the morning, right before sunrise, as it’s the only time one can have the area free of people.

I’m including a behind the scenes photo, even that it’s not so good. It’s hard to get a nice photo in the dark with a phone, even with my Lumia 1520, that has a great camera :)

This is a HDR from 4 exposures, created in Oloneo Photoengine, finished in Photoshop.

The bastion stairs

At the Margaret bridge

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Of course while in Budapest I took also few other photos, not just the firework ones. But thanks to the weather I was not able to take many, as it was raining a lot. But luckily, few hours before the fireworks, it stopped raining, and started only few hours after. Usually I have worse luck with weather, so it was nice for a change :)

So for today, I have for you a photo of the Margareth bridge. I managed to stop by it the only evening I had. It’s one of those bridges, that are just so horrible to edit in photos. Yellow lights combined with a yellow bridge, just make for a bad combination. But it still looks nice :)

This is a manual blend from 5 exposures, combined with a HDR created in Oloneo Photoengine.
At the Margaret bridge

Stunning fireworks

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Behind the cameraAs you probably expected, another fireworks photo for today. I have taken quite a few I want to edit and share with you :) The fireworks this year in Budapest were really stunning, and I think quite different that the ones from last year. They just were a little problematic to capture in photos, as they created a lot of smoke, and were not consistent. What I mean, they changed a lot between very bright and not so bright explosions. So I had to change the camera settings very often, and it was very hard to get a nice exposure. But luckily, the RAW files can get a lot of info, and can correct for a lot :)

Same with this photo. It would be probably better with a little shorter exposure time, as it ended up being quite busy, but I still like it. It’s a single exposure edited in Lightroom, Oloneo Photoengine and Photoshop.

I’m also including a behind the scenes photo, so you can see where I was standing while taking this. It was actually in the middle of a hill, so I had to be very careful not to just roll down :)
Stunning fireworks