Archive for June, 2008

HDR images for fun and profit

no responses

Well, fun anyway…

HDR stands for High Dynamic Range. Often explained as “seeing more like the human eye”, HDR imaging combines several shots of a single subject (usually static ones for obvious reasons) in order to overcome the exposure range limitations of traditional single-shot photography. The resulting images have much more detail from shadows to highlights, and everywhere in between.

Take the second shot below – Sycamore Street, Newcastle Emlyn. When standing in the street, with the sun from the left casting a shadow across the street, My “high dynamic range” eyes could see into the shadow while also seeing the sun-drenched right-hand side, however every attempt at a single shot of the scene was either too dark in the shadow or too light in the sunshine. So I set my Lumix L1 to autobracket two shots “under exposed”, two shots “over exposed” and one in the middle. I put the camera on a tripod and risked life and limb standing in the road.

Back at my computer I would normally import my RAW images into Adobe Lightroom, choose the best one or two then adjust the exposure, fill light etc etc in an attempt to create an image as close as possible to what I had seen. To create my HDR image, I imported the RAW files directly into Photomatix HDR, which automatically aligns them and combines the multiple shots (some people take as many as 12 of single scene) into a single HDR file or “HDR negative”.

This file looks aweful on your monitor and would print badly too, because nether can deal with the huge 32 bit colour depth (a JPG file is 8 bit) of the HDR image. Enter the “tone mapping” tool in Photomatix. Remember our HDR negative contains all the information from 5 shots at different exposures. Each shot will contain optimal infomation about a particular part of the subject. The tone mapping tool allows me to adjust how that information is combined and get the best Low Dynamic Range (LDR) image for screen or print.

Whan I’ve finished moving the 20 or so sliders and controls and over-worked my computer’s cooling system (processing 32 bit images takes a lot of oomph!), I click the button for Photomatix to produce the finished image which I can then save in PSD, TIFF or JPG format.

My aim with HDR is to create an image as close as possible to what I saw when taking the photo. Many people create “super realistic” photos with grossly exaggerated colours and effects. I personally don’t like them, but then I don’t like figs, beef or margarine, but somebody must….

The images below are 1,500 pixels wide. Too see them full size, click on them thumbnail, then click “full size” at the bottom. Your browser might then shrink the pic to fit your screen, so you may need to do another click to overcome this.

I’ll be adding more to this collection as I create them, so come back again!

↑ Back to top ↑