Blink Comparator






After shooting pictures of stars clusters, nebulae, galaxies and so on, often you would check if there are changes compared to the “normal" appearance of the photographed area.

 To do it, usually you have to search for a picture (or map) of the same area and check brightness and location of each object.

Unless you have a blink comparator,  that, alternating the vision of two shots obtained at different times, allows to detect and highlight changes or transient phenomena (like comets, variable stars, novae and supernovae, asteroids etc.).

Blink Comparator App is dedicated to Amateur Astronomers who like to take pictures of the Night Sky. The app runs on iPhone and iPad and  allows to compare two images of the same area taken at different times: if there are changes, they are highlighted by the blinking of any object (like star, asteroid, comet, etc.) visible in one of the images only, or that  changed position between a shot and the other.

How does it works

In Blink Comparator two pictures o the same area, a sample and a reference, are shown alternately after being loaded and aligned.  If  an object is present in only one of the pictures,  it blinks and can be easily found and marked. Instead, if an object has changed position between two consecutive shots, during the animation it  bounces back and forth, showing the path traveled.

Steps to make a blink animation:

  • Load two pictures, a Sample and a Reference, from the local Photo Gallery or from Dropbox. The sample image is the picture that you want to check. The Reference can be any picture of the same area, if possible taken with the same or similar instruments.

  • Align the two images: just mark the same three stars on each picture and press a button:  the sample image is rotated, resized and moved to overlap the reference picture.

  • Start blinking pictures.  

In addition you can also:

  • set blinking time interval;

  • zoom and pan the animation to frame a specific area or to examine in detail the images;

  • insert a mark to highlight an object;

  • add a label to describe  subject,  date and time of shooting and so on;

  • save animations as short movies  in your local Photo Gallery;

  • save movies converted to negative too.