PHOTOGRAPHY

HDR Photography Tutorial

HDR Tutorial Part 1: The HDR Photography Process

The part 1 of this HDR tutorial describes the workflow of HDR photography and processing. The path from photography to the final image is pretty complicated. The whole process can be divided to the following steps:

• Photographing for an HDR image
• Merging the photos
• Processing the HDR image
• Tone Mapping (Converting the HDR image to a normal photo)

Photographing for an HDR Photo

The first step is to take the same photo several times with varying exposures. This process is explained in detail in my other HDR tutorial.

Merging the Photos to an HDR Photo

When the photos are taken, they are merged to form one HDR Photo. There are several HDRI software for this purpose such as Photoshop and Photomatix. They both have automatic tools for merging several photos to form an HDR image.

Processing the HDR Photo

The third step is the processing of the HDR photo. Unfortunately several Photoshop tools, such as Curves or Color Balance, are not available (in CS3) when working with an HDR photo. HDR photos are processed with the same basic digital image processing operations (cleanup, color correction, cropping, sharpening) as normal photos are. (This process is described in more detail in my Photoshop HDR tutorial).

Tone Mapping

The last stage in an HDR photography and processing workflow is tone mapping. Tone mapping is the process where the 32-bit HDR photo is converted to a normal 8- or 16-bit photo. In this process the color values of the HDR photo are mapped into the color space of a normal photo. This step is necessary because neither photo paper nor today's monitors can display the dynamic range of an HDR photo. One might wonder what is the point of HDR photography if the end result is just a normal photo. The benefit of HDR photography is the possibility to create higher quality photo with noise free details in both the brightest highlights and the darkest shadows. (Tone Mapping is described in detail in my other HDR tutorial)

HDR Tutorial Part 2: Problems in HDR Photography

The second part of this HDR tutorial concentrates on the downsides of HDR photography:

• The Process of Creating an HDR photo is pretty laborious and complicated
• HDR photography is suited well only for immovable subjects
• HDR Processing requires a lot of computer resources
• Normal photos are often little sharper than HDR photos

The Process of Creating an HDR Photo is Pretty Complicated

Its pretty laborious task to create and process an HDR photo. It starts from the photography and ends with the tone mapping. A photographer who is accustomed to RAW processing and combining several photos, can feel quite at home when creating HDR photos, but for a beginner there is a lot to learn. The process can be made easier by using a digital camera and software that are well suited for HDR photography and HDR image processing.

HDR Photography Is Suited Well Only for Immovable Subjects

In HDR photography one takes several photos from the same scene, with varying exposures. Therefore HDR photography isn't suited well for moving subjects. Moving subjects are at different locations in different shots which causes serious problems in post processing (ghosting). Common moving subjects that one should be aware of are for example people, cars, birds and vegetation and clouds moved by wind. (Read Mike Savad's HDR tutorial to see how he deals with moving subjects).

HDR Processing requires lot of Disk Space, RAM and Processing Power

HDR photography aims to go around limitations of a digital cameras and to produce higher quality photos. Therefore it's logical to use the highest resolution and the best image file format available. For example I use Nikon 300D for my HDR photography and often take nine 14-bit raw photos. They consume a lot of disk space and the process of merging the photos to one HDR photo takes a lot of time.

Normal Photos Are Often Little Sharper than HDR Photos

Its logical that HDR photos might be little softer than normal photos. There might be some camera or subject movement between photos which might cause some softness to the HDR image. But I don't see that as a real problem. Firstly, the difference in sharpness is small in properly created HDR photo. And more importantly, properly created HDR photos can be practically noise free which means they respond extremely well to sharpening.