HDR photography complete guide - Photography Course - Lesson 28

Photo by Bruno Ciampi Flickr.com/photos/brunociampi/
This article is part of the online digital photography course.

Much has been written on the HDR (High Dynamic Range), above all about the shooting technique and the used software (Photoshop, Photomatix Pro, Easy HDR etc...).

To really create an HDR let's start from the basics.

HDR photography consist in going over the physical limit of the sensor increasing the extended dynamic gamma thanks to the chance of combining in post-production or during the shot three or more pictures with different exposures, this entails that the photographed scenes have to be static and so a tripod becomes essential.

Many are sure that this technique will lead to obtain pretty contrasted pictures with supersaturated colors, there's nothing more wrong; what you see in that kind of pictures is just a horrible post production that sometimes can turn out to be interesting if well realized.

But, what characterizes a real HDR picture? It gives a dynamic gamma superior to sensor’s one, with wide shadows and high light although in presence of strong contrasts. Obtaining a picture impossible to do with a normal sensor, because it would close the shadows or burn the high lights.

From this explanation it can be understood that it isn't possible to obtain an HDR photo from a single shot, because you have no way to go over the dynamic gamma limit of the sensor, you can't have the information of more shots in a single one.

To realize HDR pictures you need:

  • The first picture to expose the high lights
  • The second with a medium exposure
  • The third exposing the shadows 
By merging these three pictures you obtain one with a richness of colors and details higher than the single one.

A curiosity: HDR photographs should appear more realistic than a normal picture, because the human eye is able to recognize more details than a sensor in both light and shadows!

Now I want to tell you about something that you can't usually find in HDR photography tutorials, it was written by a coworker of my blog whose name is Sabrina Campagna.

To obtain images really significant and noteworthy what really counts is the first image, the starting one. To obtain its best, the shot has to be taken in not extreme lIn the third case too pale or gray skies may give you white stains where the program can't find fitting colors for the mapping. That happens mostly on the parts where the color tends to white, so the stain will be a white/gray with irregular borders (as in the image). In the fourth and last case, happens something similar to the previous. The sun on the peak can create unbalance in the original shot, because unless you center perfectly the image the sky will tend to white until completely "burning" during the mapping. The excessive refraction of the UV rays can, in addition, create a discoloration also on other picture areas rendering the HDR useless. The best subjects to photograph in HDR are the architectural subjects or also those rich of details that will be highlighted by the HDR fusion.ight conditions.

The rules of the first shot are the following:

  1. No strong back light.
  2. No to an excessive presence of black in the picture (as night photos taken with short shutter speeds).
  3. No gray skies.
  4. No strong sunlight.
In the first and second case, in fact, cause of the elaboration, the HDR results mostly with a washed-out and noisy black that, to be corrected, will require a high contrast that will bring the pictures more or less to its original tones of silhouette or nocturne.

In the third case too pale or gray skies may give you white stains where the program can't find fitting colors for the mapping. That happens mostly on the parts where the color tends to white, so the stain will be a white/gray with irregular borders (as in the image).

In the fourth and last case, happens something similar to the previous. The sun on the peak can create unbalance in the original shot, because unless you center perfectly the image the sky will tend to white until completely "burning" during the mapping.

The excessive refraction of the UV rays can, in addition, create a discoloration also on other picture areas rendering the HDR useless.

The best subjects to photograph in HDR are the architectural subjects or also those rich of details that will be highlighted by the HDR fusion.

HOW TO REALIZE AN HDR - Post production phase - written by Gianluca Nespoli

In this tutorial we'll study how to create an HDR image through Photomatix and the subsequent optimization through Photoshop, all starting from three pictures done in RAW format.

The shots were done with a reflex Canon 30D and a lens Canon 10-22mm. Aperture f/9 with times of 1/8s, 0.5s and 2s. As you can notice the times are exactly to + and - 2 stops with a reference value of 0.5s.

The pictures have been taken at the science museum in London, ideal environment to use the HDR technique, placing the camera on a backpack because the internal rules of the museum forbid to use a tripod, in bracketing mode and automatic shutter release to avoid any kind of movement of the camera during the shots.

1 - Creation of the HDR




To create the HDR we'll use a good program called Photomatix Pro, easy to use and pretty intuitive (there are many tutorials on the net to delve into its features). Working with TIFF images at 16 bit the result will be similar to the next image (32 bit):


After setting the real engine of Photomatix, that is the "tone mapping", we'll have a TIFF image with 16 bit per channel:


Setting the tone mapping at your pleasure will be pretty easy thanks to the plain interface. The difference between the two pictures is obvious but still not quite satisfying... a yellow dominance a bit faded. What are you going to obtain with Photomatix will be a picture similar to this one:


Details retouch

Let's pass to the finishing phase to render the image a bit more engaging. Mainly we'll work on lights, shadows, tones, contrast and sharpness. Opening the image previously saved with Photomatix, let's duplicate the background level and modify the exposure (image>regulations>exposure)


Let's continue desaturating the yellow (image>regulations>Tone/Saturation)


Let's raise the sharpness of the image by using a contrast mask:


(in this case I preferred to immediately raise the sharpness instead of doing it at the end), let's merge everything and duplicate the level created this way.

Apply the Gaussian blur filter in overlay mode at low opacity (14% may work for our purpose) by doing that we are going to increase the image color making it more full-bodied:


Let's merge the level again and duplicate the resulting level.

image > regulations >lighting/contrast using the following values: lighting -3; contrast: +3 Merge it again and duplicate the level.

Image > regulations > curves


Merge everything and duplicate the level.

It can still be seen a yellow dominance that, personally, I don't think is appropriate. Let's then repeat the yellow desaturation with a value of -65 and setting, for the superior layer (normal mode), a 75% opacity. Merge everything and duplicate again.

Now we have to try to raise the “tridimensionality” of the subject by emphasizing the light dots with the brush tool in overlay mode with an opacity around the 18% and using the white color. The same procedure will have to be used for the dark areas using the black brush (alternatively we can use the burn and dodge tools).

The brush size will have to be varied depending on the area we are going to work on. Let's merge everything one more time and duplicate the level.

Now pass in 8 bit mode and use the effect filter paint daubs.


Now lower the opacity of this level to 30% and in the parts where the effect seems to be too marked (in this case on the car's radiator) use the rubber tool to render visible the inferior layer.

I’d say that our job is finished!


In conclusion

As you may have realized this isn't "THE" method but a method that has to be adapted to the picture we have to work on. For a good result the important thing is to start from a decent picture with the less noise possible, because the HDR tends to emphasize it. Not all subjects are fit for this kind of elaboration, metals and reflecting surfaces, instead, will give remarkable results. Starting from a much contrasted subject the final image will result as much well exposed and pleasant but you will require more shots... 5, 7 or even 9.

A similar although more rough effect, can be obtained from a single shot: developing in different ways the same raw file starting the lighting from time to time.

Experiment, experiment and experiment again. I hope I haven't been too boring or dispersive but somewhat of help in pulling you closer to this photographic technique.

Translation by Nina Kozul

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