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9.21.2008

HowTo: HDR Photography for free w/ Qtpfsgui

I've been playing with HDR photography as of late.

If you're not familiar with HDR photography, it is a system to capture the dynamic range of 3 or more differently exposed images into one. This means the new image contains all the good details from three images...so your highlights aren't all blown out and white, and your shadows still have detail in them instead of just being plain black. You're going to use software to merge your multiple exposures into one very detailed HDR file, usually in EXR format. These HDR files have a greater dynamic range than normal monitors or printers can output. Once you have created an HDR file, you use tonemapping to convert it down into a conventional image that our puny earthling monitors and printers can output. The tonemapping plugin or software is going to smoosh all this extra visual data you collected down into a plain old Photoshop or JPEG or other "normal" image file. This is similar to taking a very detailed audio recording and converting it into an MP3.



While playing with HDR it's fun, I'm not making my living on photography. I can't justify going out and buying Photoshop right now. I can get by between my copy of Elements and GIMP.
Last time I checked, Photoshop could create HDR, but didn't have a tonemapping plugin yet. So you'd still have to buy additional software.

I discovered a cool piece of free software (open source) that can do HDR image creation and tonemapping. It's called Qtpfsgui. You can download it here. It's cross platform, so it runs on Mac, Windows, or Linux. I'm using it under Vista Home Premium 32-bit with no problems.

The only glitch I've noticed is that sometimes the progress bars will hang for a long time, and it may seem like the application is frozen, but it's actually still running, HDR imaging is just very processor intensive. You'll notice this more on slower computers or older notebooks. It's not noticable on my Core 2 Duo desktop, but alignment and tonemapping can take several minutes on my 1GHz Pentium M notebook.


I found a very good newbie friendly guide to using Qtpfsgui to create High Dynamic Range images here: http://www.dtgeeks.com/journals/article/hdr_imaging_explained/


Give that a read and then download Qtpfsgui and give it a try.


Remember to save your HDR image as an EXR file before you move on to tonemapping. I recommend doing test tonemaps using the various presets at low resolution to figure out your settings before doing a final tonemap at high resolution.

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