Playing around with CHDK and HDR imaging

I had stumbled upon the CHDK firmware for Canon cameras through a Wired article some time back, and finally got around to trying it out on my PowerShot A630 today. I also discovered that it is possible to create HDR images by shooting images at different exposures and subsequent manipulation through appropriate software (tutorials: Photoshop / CS2, GIMP / GIMP using a script, Paint.NET or Photomatix).

So, the first thing I did was to download the CHDK build for my camera (I used the AllBest oneusage instructions). Then, I followed the instructions and copied the files to a spare SD card I had, and put it into the camera. I started the camera in play mode and used the menu to activate the CHDK firmware (this is only temporary, and needs to be activated every time the camera is switched on). Once activated, I could switch between the two versions using the Print button. There are a ton of options in the CHDK menu including support for scripts (written in uBasic), enabling additional shutter speeds and indicators among many others.

With the firmware nicely set, I went ahead and started shooting for making HDR images. Initially I tried an HDR bracketing script available to shoot some of the photos. The script seemed to have some problems focusing at times, but I managed to get some shots. I also discovered the ability to do exposure bracketing in the continuous shooting mode, which I also used to shoot a few photos.

I then used the trial version of Photomatix to create the HDR images as I was feeling too lazy to go through all the steps to create HDR images in GIMP (there is a contrast blending script which takes of this though) or Paint.NET. The only drawback of using the trial version is that it inserts a watermark into the end result. This is ok since I was experimenting with HDR imaging, and I’ll switch to GIMP or Paint.NET for serious photos. One of the things I noticed in the resulting HDR images is that they can tend to look a bit cartoonish or unnatural.  Anyway, here are a couple of results.

I have created a collection on flickr for the HDR images (both sources and results are included). I’ll be adding to the collection as and when I get the opportunity. There are quite a few HDR groups on flickr too, and they do have some good looking photos. For something more interesting, have a look at this (not by me).

Update: Just discovered an open source HDR imaging software – Qtpfsgui. The output (sample on this post) appears to be a bit more cartoony due to a different algorithm being used. (via)


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