torsdag 21 juli 2016

The effect of dithering

Some time ago I wrote about how dithering can improve the quality of raw images.
If you control your camera and mount from a computer, you can use software to apply small mount movements between exposures. Some programs use random movements of the RA and DEC axes to avoid patterns in your stacked images.
Unfortunately, almost all camera control software is written for either Canon or Nikon cameras. Since I have an old Pentax camera, which has a quirky usb connector, I can't control it from my computer.
I've written about my ditherbox earlier. Here's an example of how it works.
This short video shows the effect of dithering. M45 was the target, and some 46 images were taken and registered. Before registering, the target is placed on different parts of the sensor according to the dithering pattern. After registering, the target is stationary, and the noise pattern moves against the dithering pattern. This is clearly seen in the video.


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