Blinking and animation
The BLINK command can be used for compares two images by displaying them successively and cyclically on the
screen. The syntax is
BLINK [NAME1] [NAME2] [DELAY]
The names of the two images are in the parameters [name1] and [name2]. The images may have different sizes. It is recommended to adjust the dynamic and offset of images to minimize flickering effects between the images. The blinking time may be adjusted with the [delay] parameter that contains the visualization time of an image in milliseconds.
During blinking it is possible to adjust visualisation threshold, color palette, use some processing command like TRANS for register dynamicaly the two images... Processing concern the image [name1]. Example
>BLINK M51_1 M51_2 200
To stopping the blink enter the command:
The BLINK command is a powerful tool to bring out any difference between two images. It can be used for many kinds of investigations: detection of supernovae, novae, variable stars, comets, asteroids, etc.
The BLINK2 command
is similar to BLINK command
but for 3 images instead 2 (that allows sometimes better identification of
moving objects). The syntax is
BLINK2 [NAME1] [NAME2] [NAME3] [DELAY]
>BLINK2 ASTER1 ASTER2 ASTER3 200
For animate a large number of image, invoque the Animate dialog box (View menu):
Push the Stop buttom for stopping the animation.
Animation d'une séquence avec interpollation
PIC_ANIM is a powewful command for improve fluidity of the animation of a sequence. For that of the intermediate images are calculated by linear interpolation starting from the acquired images.
The syntax is: PIC_ANIM [INPUT] [OUTPUT]
The parameter [INPUT] indicate the name of a text file which respectively contains on two columns, the name of the acquired images, and date of acquisition of these images (or all other identifying function of time, for example an index value which goes increasing).
The parameter [OUTPUT] indicate the name of a text which respectively contains on two columns, the name of the interpolated images, and dates for which the interpolation is calculated (or an identifier function of time, in conformity with that used in the input file).
Here an application example application on the trace of a bright Leonid meteor. The observation was carried out by Franck Vaissière by using a modified webcam Vesta Pro on November 19 2002. The lens is the origin objective of the webcam. Here 3 images extracted from a sequence of the event:
Suppose 5 images to be interpolated with the names MET1, MET2, MET3, MET4 and MET5. We create in the working directory a text file of name IN.LST containing:
We create the output file OUT.LST:
The images R1 and R5 for example will be identical to images MET1 and MET2 (correspondence of the dates). But moreover, between the two images observed, command PIC_ANIM will generate the intermediate images R2, R3 and R4, and so on for the whole of the sequence.
Note: file OUT.LST can be creates automatically with the assistance of command GEN_OUT, which is quite practical for long sequences. In the example one will make:
>GEN_OUT OUT R 1 5 0.25
After having saved the file IN.LST and OUT.LST, we produce the interpolated sequence:
>PIC_ANIM IN OUT
The sequence R1... R17 synthesized can be visualized with the Animation command from View menu. You can also save the sequence in the form of BMP images for produce an animated GIF or a AVI film for example with the assistance of an adequate software:
>PIC2BMP R RR 17
You have now on the disc a sequence RR1.BMP..., RR17.BMP.
Here the animated sequence of 27 images of the object which shows the trail well distorted by high altitude differential winds velocity:
Click on the image for display an enlarged version (750 Kb)