In the world of HDR imagery, Photomatix is the leading application. However, if you only occasionally need to assemble an HDR sequence, you can save your pennies and use the open source application, qtpfsgui. In this post I’ll show you where to find the application and how to get started using it:
If you are starting out in HDR check out my earlier post to see how to capture your bracketed sequence of images to use for the HDR assembly.
Visitand download the appropriate version of qtpfsgui for your system. I’m using a Windows machine so I’ll download version 1.9.3 and I’ll choose the setup.exe version.
When you click the link, you’ll be taken to a download page where things rapidly go from simple to downright confusing. For the Windows install, scroll down to find All Files > qtpfsgui > 1.9.3 > Qtpfsgui-windows-SETUP-v1.9.3.exe and download and install that file.
Launch qtpfsgui and select New HDR > Load Images. Select the images in your HDR sequence. When they appear in the list you’ll see the program has guessed the exposure compensation used for each. If this isn’t correct – and it is seldom so in my experience, select each image and adjust the exposure compensation value manually by typing the value into the dialog. So, because my sequence was captured at 0.5, -1.5 and 2.5 I entered those values.
You can set the program to auto align the images by selecting Auto align images and then select the option to use – HUGI’s Align Image Stack or Medium Threshold Bitmap. My experience is that this fails spectacularly every time I try it – the program crashes and I have to start over, but your mileage may vary. If you have problems, bypass this and you can manually align them yourself shortly.
Click Next and wait as the HDR sequence is assembled. When your image appears, zoom out to see it all. Now you can fix any alignment issues. If you see white haloing around objects in your images you need to fix this. To do this, click each image in the editable images list and see if there is any haloing in that image.
If you see it, adjust the image using the arrows in the Shift Values for Editable Image area of the dialog. Move the image until the haloing disappears or is minimized. Continue to do this for all the images in the Editable list. From the Preview Mode dropdown list you can choose from various preview modes which can help you identify alignment problems. When your sequence is aligned, click Next and then Finish to assemble the HDR image.
This is the assembled image and, at this point, you can select Save HDR As and save the image as an HDR format file. Later you can open this in the program to work on it and you will not have to realign and re-render it.
Before you can actually use the image, you need to tone map it so select the Tonemap the HDR option to open the image ready for tone mapping.
To view one of the tone mapping options, select Fattal as the operator and click Apply. A small version of the image appears tone mapped to the specifications shown.
Change the image size by selecting a different size from the Result Size options and click Apply to create a second version of the tonemapped image.
Each time you click Apply you get another image so the screen can start filling up very quickly. You will find larger size images take more time to render so start with small versions until you find an Operator and settings that work for you then render larger versions as you fine tune your settings. Here the larger size image is showing noise not apparent in the smaller image.
Continue to experiment with options by choosing different settings – sometimes small differences in values can result in sizeable differences in the images and you can also use other Operators if desired.
Render the images you like at a good size and close any smaller versions or any images you do not like. While qtpfsgui has a Levels adjustment option, it is best to save this adjustment and do it in your editing program later on.
To save the images, click the Save or Save All button. Make sure to specify the folder you want the images saved into – on my computer, scarily, it defaulted to one of my Windows system folders – not where you would want to save them! Once saved, you can open the image in your favorite editor and work on it further there.
To learn more about the various operators, how they impact an image and which you might use for what type of image, visit http://osp.wikidot.com/parameters-for-photographers