What is High Dynamic Range (HDR) photography?

At times people ask me what HDR pictures is. This photo-blog site provides an overview so that you can choose the to start with ways in exploring this wonderful earth.

Only set, a scene has a large dynamic vary if there is a large contrast among the darkest place and the brightest place on the scene. HDR pictures attempts to capture the dynamic vary in entire, then decreases the dynamic vary of the impression for exhibit.

There are two use scenarios for HDR pictures:

      one. Seize a scene that has a large dynamic vary the way our human eyes can see it, and then exhibit the scene on a monitor or printout that has a decreased dynamic vary. In other words and phrases, we can use HDR to do the job all around the limitation of existing exhibit technologies. Architects and authentic estate brokers like to use HDR processing to deliver images that show rooms and vivid landscapes with nicely balanced brightness. This can be accomplished by compressing the dynamic vary.

      two. Use HDR processing for artwork. Superior HDR software program has a lot of sliders to adjust the appear of a photo. An artist can use that and allow his or her creative imagination soar to build creative images. The HDR guru in this area is Trey Ratcliff of Stuck In Customs – his do the job is only awesome. He also gives very good HDR tutorials, go examine them out (with this website link you get ten% price cut).

Individually I like both use scenarios. I strive to build HDR images that are creative, and at the identical time do not appear way too unrealistic.

Let us dive into details. So what is “dynamic vary”? It is the distinction among the darkest place and the brightest place on a scene. The brightest place in this example scene is someplace in the glass ceiling, the darkest place is likely the black cooling grid on the fish tank on the suitable side. The dynamic vary is a relative measure. For illumination it is normally measured in “f-stops”, also named just “stops”. 1 f-halt represents two occasions distinction in illumination, two f-stops is four occasions distinction, 3 f-stops is 8 occasions distinction, etc. As you can see, f-stops are on a logarithmic scale.

To give you an concept, the dynamic vary on a cloudy day is about 8:one, or 3 f-stops. A photo on a foggy day can be even decreased. On the other excessive, a scene that features a somewhat dim place and vivid landscape outdoors can address a large dynamic vary of fifty,000:one, or sixteen f-stops.

No technologies can at present match the ability of the human eye in phrases of dynamic vary. The human eye can see objects in starlight, as very well as in vivid daylight, which usually means we can see a dynamic vary of up to one,000,000,000:one or thirty stops if we choose the iris into account! As you know, it normally takes time for the iris to regulate to various a brightness stage all around us. Taken the iris out of the equation, the retina can address a dynamic vary of all around a hundred:one, or about 6.five f-stops. Specified a few seconds time, the human eye can address a substantially larger sized dynamic vary if you choose the aperture of the iris into account.

The ideal CMOS impression sensors these days have a measured dynamic ranges of about eleven,000:one, or 13.five f-stops. Having said that, a JPEG impression of an common level and shoot digicam covers no additional than a hundred:one (6.five f-stops).

A very good excellent Lcd exhibit has a contrast ratio (dynamic vary) of about one thousand:one, or ten f-stops. A printout on paper can attain a dynamic vary of about a hundred:one, or 6.five f-stops.

Okay, now how is it attainable to capture ten or additional f-stops of a scene, and then print it out on a media that has just 6.five f-stops? This is wherever HDR processing will come into participate in.

The to start with action is to capture the finish dynamic vary. DSLRs and morror-much less cameras can keep images in Uncooked structure in addition to JPEG structure. Uncooked images can address a increased dynamic vary, usually 8 or additional f-stops. This is ample in a lot of scenarios to address the finish dynamic vary of a scene. I normally shoot in Uncooked + JPEG, which provides me the simplicity of use of JPEG and the flexibility of Uncooked documents.

What can you do if the dynamic vary of the impression sensor or the Uncooked file is not ample to capture a scene? In this circumstance you can choose a number of exposures at various brightness levels. DSLRs and mirror-much less cameras offer a so named bracket manner that does that. You pick out how a lot of exposures you want to choose, and what the gap in f-stops is among the exposures. I normally shoot 3 exposures with two f-stops gap. Bracketed exposures really should be taken in aperture manner so that the depth of area does not adjust among the exposures.

To get superior final results in the HDR put up-processing it is very good to shoot with a reduced ISO. I normally shoot in a hundred ISO when I do HDR pictures. In a natural way, a tripod aids in holding the bracketed images aligned and the digicam additional steady – a aspect to think about when capturing in reduced ISO thanks to greater exposure time.

The following action is to build an HDR photo from one particular or a number of impression documents, preferably in Uncooked structure. This can be accomplished in Lightroom, Photoshop and other impression software program that supports HDR. Having said that, if you are serious about HDR pictures I recommend acquiring specialised HDR software program for the reason that it gives substantially additional flexibility, and you have substantially additional control more than the appear of the closing impression. I use Photomatix Pro and I am incredibly delighted with it. This is also the software program of option for Trey Ratcliff.

There are two techniques to blend a number of exposures into a solitary impression: Exposure fusion and HDR tone mapping. Using exposure fusion, each and every pixel is picked from on of the resource images dependent on the most proper exposure values. With HDR tone mapping, the large dynamic vary is compressed to a usable vary. Both of those techniques outcome in an impression that can be shown conveniently on a media (Lcd exhibit or printout) that has a substantially decreased dynamic vary than the full vary of the resource images.

Now on to a concrete example proven in this photo. I took 3 exposures making use of a tripod inside the Ferry Terminal shortly just before the shops opened. The to start with one particular is overexposed by two f-stops, the next one particular has regular exposure, and the 3rd one particular is underexposed by two f-stops. The impression underneath is the HDR photo immediately after tone mapping. You can see that the somewhat dim shutters are taken from the below-uncovered impression, the floor and ceilings are taken from the next exposure, and the incredibly vivid glass ceiling is taken from the underexposed impression. The outcome is a very well-balanced impression that displays all the details, no matter of the first brightness.

With very good HDR software program there are a lot of options to adjust the appear of the resulting HDR impression. Photomatix Pro has 15 sliders to determine the appear of a tone mapped impression, this kind of as HDR strength, tone compression, white balance, gamma, micro-smoothing, and additional. To make it less difficult for consumers they offer presets with expressive names, this kind of as “balanced”, “normal”, “paintery”, “enhanced”, “deep”, “surreal”, “tender”, etc. I normally pick out a preset I like, then fine-tune the appear of the impression making use of the sliders.

Most of the time I create additional than one particular HDR edition from a established of resource images. I then cycle by them on a major watch and pick out the one particular I like most. Extra normally than not I like one particular segment of an impression in one particular HDR edition, and an additional segment in an additional HDR edition. For example, wood seems to be incredibly nice in paintery HDR, but the sky seems to be kind of crappy. The sky seems to be nice in tender HDR, but wood seems to be bland and boring. In scenarios like this I selectively copy more than some elements of one particular HDR impression edition into an additional.

Right after HDR processing I do some closing touches, this kind of as cutting down the coloration saturation, adding some highlights and shadows, or straightening out the impression.

As you can think about, there is a great deal of do the job in all of this processing. Every photo I put up on Flickr normally normally takes one particular hour or additional to method right up until I can give it thumbs up.

Smartphones also have an HDR manner, and there are specialised HDR photo apps for smartphones. I attempted out a selection of them. None appear even shut to the flexibility of specialised HDR software program – you just click and get the outcome. I are likely to stay away from HDR on smartphones, and only use it if I do not have my Sony NEX-6 with me.

Let us appear at the excellent of HDR pictures. Some people have a adverse bias toward HDR pictures for the reason that there are a lot of HDR images that are “overcooked”. Primarily when starting to take a look at HDR it is straightforward to apply way too substantially HDR for coolness aspect. Shots processed in a surrealistic or unnatural way may well appear appealing at to start with, but are likely to get boring very immediately. So I recommend that you don’t go overboard with HDR processing.

There is a next excellent aspect to think about. HDR processing decreases the dynamic vary, by definition. The minimized dynamic vary may well outcome in images that appear bland or “flat”. When you do HDR processing it is very good to pay out awareness to the highlights and shadows, and tune them so that the impression seems to be normal. My personalized requirements in common is to make an impression seems to be creative, while at the identical time holding it as normal as attainable. When you start off with HDR pictures I recommend to participate in all around to find your own design and style.

Some people do not like any kind of impression manipulation – they say, if it is not straight out of the digicam it is phony. Artistic HDR processing absolutely manipulates images, so HDR images are not to everybody’s style. I am great with that, artwork is a incredibly subjective make any difference. Think about this if you are in the “photo have to be as reasonable as attainable” camp:

      one. The human eye and mind method visible info in a non-linear and unpredictable way. You likely have observed optical illusions that astonished and fooled you. That is, items are not normally as they seem. With creative HDR processing it is attainable to build imagery that is less difficult for the mind to method, or that seems to be additional satisfying than the true scene. Artwork is a incredibly subjective make any difference however – what one particular human being considers a masterpiece, may well be an uninteresting piece of do the job for an additional human being.

      two. A electronic digicam converts impression sensor data into a JPEG file. A great deal of processing is accomplished at that stage – the digicam maker helps make a decision on white balance, gamma, saturation and a lot of other aspects that determine the appear of the JPEG impression. There is no this kind of matter as a “authentic photo”.

With this blog site I am just scratching the floor of HDR processing. Allow me know if it served you recognize the earth of HDR pictures. Allow me also know if you have any queries, I will reply and I may build follow-up posts.

— Peter Thoeny, Good quality HDR Photography

– Text: Copyright 2014, Peter Thoeny, CC BY-NC-SA two.
– Photo: HDR, 3 Uncooked exposures, NEX-6, DSC07422_3_four_hdr3pai3howto2

Posted by PeterThoeny on 2014-03-26 01:44:fifty seven

Tagged: , HDR , HDR tutorial , HDR introduction , blog site , photo blog site , Higher Dynamic Range , HDR pictures , fav30 , tutorial