Sunday, 23 November 2014

HDR photographs (2)

Continued from HDR photographs (1)

Against the Light
If you are stood inside a dark building with a bright light shining into and dazzling your eyes. If you look around and shade your eyes you will be able to make out some of the details. Your eyes adapt to the prevailing conditions. However, if you try to take a photograph nothing will turn out. The problem is not with your camera.  The issue is that the dynamic range (tonal values) of the scene exceeds what the camera is capable of capturing. 

Yet photography against the light can create some very evocative and mood rich images.  Here is one image looking directly at the sun. this creates deep shadows and plenty of reflections.
Shaded Sun

However, it is possible to improve the tonal range of your camera using HDR techniques. To take HDR images (High Dynamic Range) you need a camera set up on a tripod so that the images taken stay in register. Later, when the images are combined together, each overlays over the top of the other. If the images are slightly different the images may be blurred. (more on this later) 

Here is an image where the sun is shaded out by the trees and clouds. Thereby creating a rich strong sunset image where the reflections also play a big part.

However, some DSLR cameras (digital single lens reflex) can take, two, three or more images at different exposures almost instantaneously. My Canon 550D has an option where three photographs are automatically taken, at three different exposure settings. Some modern smart-phones such as the Samsung S4 also have HDR built in to the camera.

There are a number of bits of software that you can download for HDR combining and editing of digital photographic images. Some of the software can also correct images that are out of register. (often called ghosting for obvious reasons)

Fusion-HDR: This program allows you to enhance and combine multiple images. It is also able to separately align and correct hand held images. Best results were obtained using SUM operator rather than HDR operator.

Luminance HDRLuminance HDR is an open source graphical user interface application that aims to provide a workflow for HDR imaging. This software has built in automatic anti-ghosting.
Picturenaut: Picturenaut was born in the German photo community. It has been in the works for four years, with consistent improvements according to user feedback. It has always been freeware, thus setting the standard for making high quality HDR Imaging accessible and easy.

Continued from HDR photographs (3)

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