REDUC TUTORIAL
|
REDUC TUTORIAL
|
|
| Updates |
| V3.65b Reads FITS 32 bits integer Customizable cameras List False color visualization Mathematical Surface's image New formatted EZReport Last values of Delta, Epsilon & Pre-Orientation automatically reloaded BestOf optimization Bugs correction and optimization Spanish Tutorial |
| Presentation and basic features | |
| Loading | |
| Main window | |
| Files selection | |
| Sorting | |
| Centroiding ! | |
| Calibrating | |
| Measuring | |
| Publishing | |
| Advanced features | |
| Automated reductions | |
| Shift and Add features | |
| Automatic rejection | |
| Drift calibration (single frame) | |
| Drift calibration (multiple frames) | |
| Using QuadPx function | |
| Adjustment of a tridimensional mathematical surface | |
| Dark and Bias preprocessing | |
| Horizontal and Vertical swap | |
| Binning x2 | |
| Others features | |
| Language | |
| Visualisation levels | |
| Saving the images | |
| Save an image series | |
| Crop images | |
| Customizing the camera list | |
| Samples from the real life ! (FAQ) | |
| Useful Shifts and Adds | |
|
Loading frames |
|
| Select all files : Ctrl+A |
|
| Select consecutive files :click on the first file, keep the shift key pressed and click on the last file you want to select. |
|
| Select non consecutive files : click on the files with the control key pressed. |
|
|
|
|
Click Select AVI button in the conversion tool window and select the file to be converted.
|
|
|
Click the Convert button
|
|
|
Choose the library where you want the bmp files to be created and give a generic name for the files.
The generic name will be indexed automatically by Reduc. The conversion tool close automatically after the conversion and you can now select the bmp files as explained in the previous chapter. |
|
| Main Window Most of the work is done on this window, so we take a minute to localize some items
|
|
|
|
Files selection |
|
Sorting the frames In order to adapt to the various configurations of Reduc users, two options are available according to the type of pictures acquired: |
|
|
Cursor Set |
|
Centroiding !
|
| Calibrating Before reducing we need some informations : - Quadrants orientation - Relative pixel size (l x h) - Precise image orientation - Sampling (number of arcsec/pixel) |
From a standard
star : HOW TO PROVIDE
CALIBRATION PARAMETERS |
| Calibration with a calibration star It is the same procedure than a simple reduction. When the reduction is finished : Don't forget to click on Measure before measuring ! NOTE : The second reduction sheet (Reduced tab) can't be displayed when in Calibration mode |
|
|
Reduc recomputes all that is necessary immediately when you type new values. |
|
|
Others calibrations |
| Measuring After calibration we know the precise image orientation and the pixel
sampling. So we can switch to Measurement mode. |
|
| Measurement session is the easiest phase
of Reduc's learning !!!
|
|
Publishing !
|
Automated Reductions Select a good frame in the file list |
|
- In the same way, select the secondary component and adjust if necessary the size of the search box. - Then click on 'comp B' |
|
| - Finally press AutoReduc button and voila ! After a while all the frames are reduced |
|
|
|
|
| Shift and Add Features |
|
When clicking Align or Stack, you can adjust the size of the final
image as well as its centering. The effects of the adjustements are materialized
by the red/white dotted cross.
|
|
| Just after an alignment, the list of files is blue. To optimize the calculations, Reduc uses a special format and create a list of 'virtual' frames which are the result of the last alignment. These frames can be used use as if they were normal image, ie. you can reduce them or to add them (Stack List menu). The only difference is that this list is managed entirely by Reduc and that these files will be erased according to its needs. |
|
| Many possibilities are open with
these options. Look at 'Samples of the real life' section. |
|
| Automatic Rejection You can suppress the image having not enough quality. It's useful when you reduce automatically a great number of frames. In the Reduction Window select Sort>Rejection. The analysis is instantaneous and the pictures are suppressed from the reduction tabs. The criterions are very large and concern only a small amount of the frames. |
|
||||||||
|
|||||||||
|
Drift Calibration Three factors are important, the length of the trail, its duration in time and the intrinsic quality of the picture. |
|
|
CALIBRATION : |
(1)
(2) 
(3)
|
| - Click a point at the other extremity of the trail. Again choose a place where the trace is well established (fig. 4) - Click now the 'B comp' button (fig. 5) |
(4) 
(5)
|
|
- Finally click on the 'Drift Analysis' button to launch the analysis (fig.6) |
(6) 
(7) 
(8) 
(9)
|
|
Drift Calibration on multiple frames |
|
| - Select only the frames showing the movement of the star (fig. 1) |
(1)
|
| - Adjust the size of the detection box so that it includes largely the star (fig. 2) | (2)
|
| - Click on the 'Synthetic Drift' button (fig. 3) | (3)
|
| - The pictures are displayed on the screen as Reduc analys them. It is an opportunity to control that there are not any bad plots. - At the end the analysis a synthetic picture of the movement of the star is displayed and a dialog box of dialogue asks for the orientation of the picture. It is time to give to Reduc the orientation of the quadrants. Click the corresponding button (fig.4) |
(4)
|
| - The calculated value are propagated automatically in the reduction sheet. (fig. 5) - The pre-orientation is put up to date too. (fig.6) |
(5)
(6)
|
| If the curve of regression appears disjointed that is that there are probably incorrect pictures. You can modify to leisure the selection of pictures and can launch again the analysis while clicking the 'Synthetic Drift' button again. It's highly recommended to capture several drift images and to keep the mean value of their reductions as the final calibration value. |
|
|
Using QuadPx Function |
|
After QuadPx |
It is difficult to measure tight stars. QuadPx resamples the displayed image and enlarges it by a factor two while keeping constant the distribution of the light by unit of area. This method of enlarging is perfectly adapted to the measurement by Reduc because it works on this distribution. If needed QuadPx can be applied twice on the same image. Since V3.71, Reduc takes into account the scale change and adjusts the reduction automatically with Quaded images. |
Après un deuxième QuadPx |
|
| SURFACE : Adjustment of a tridimensionnal surface This feature uses the Surface algorithm especially designed to measure the very tight stars. Developed by Guy Morlet and Pierre Bacchus to measure the images acquired on the 50cm refractor of the observatory of Nice, it was until now reserved to private usage of the members of the French Astronomical Society. It is integrated in Reduc with the authorization and the courtesy of the authors. |
|
||||||||||||||||||||||||||||||||||||
|
Surface is at full power on images with a high signal to noise ratio. Therefore it is not usable in the automatic reductions. After having shift-and-added the image, the measure is made in four stages:
|
|||||||||||||||||||||||||||||||||||||
|
Dark and Bias preprocessing Recall and basic principles:
|
|
| Preprocessing activation : 1/ Clic on the Dark button |
|
| 2/ Select the dark frames |
|
|
3/ Dark appears at the right of button |
|
| Stop preprocessing : 1/ Clic on the Dark button |
|
| 2/ Choose Cancel in the dialog box |
|
|
3/ Preprocessing is stopped
|
|
|
Horizontal and Vertical Swap
|
| Langage I thank very much Edgardo Ruben Masa Martin
for the spanish translation. |
|
| Visualisation levels The visualisation levels are computed automatically by Reduc when it loads each frame. When unchecking Auto you keep the same tuning from one image to another. You can otherwise change them at any moment by moving the trackbars.
A false color visualisation can be obtained with the colored checkbox. 
|
| Saving the images Reduc is not an image treatment software but it can be useful to record an image. Two formats are possible: Bitmap and FITS ( BITPIX=16).
When saving a BMP file, the image is saved as it is seen on the screen. That is to say that the visualization settings influence the recorded picture. Therefore it won't be possible to make future measurements on this picture since the information of origin is definitively lost.
|
| Align and Crop Images | |
|
This features allows you to easily crop images :
|
|
| Customizing the camera List | |
|
Click on [...] button to customize the list. Delete a camera : blank all information about it. ABOUT THE PIXEL SIZE |
|
| Useful Shifts and Adds | ||
| When the signal of each components is sufficient for an individual reduction, I recommend to use it. Unfortunately the frames don't have always the required qualities for an individual reduction: not enough signal, too much noise ... Here are some cases where 'shift and add' can bring a solution. | ||
|
||
|
||
|
||
|
|
This chapter and the corresponding features of Reduc are dedicated the users of speckle interferometry technics. |
|
|
Reduc allows to activate / hide the Interferometry menu as needed.
|
|
|
Obtaining autocorrelogram with Reduc is extremely simple. Just click on Autocorrelation!
|
|
|
The algorithms use the fast Fourier transform (FFT). It requires square images whose dimensions are a power of 2. If your images do not follow this agreement, Reduc handles resizing before creating the autocorrelogram. Click OK on the error message and then choose a size compatible with your pictures in the next dialog box and then Ok Reduc then generates the autocorrelogram. |
|
|
In the final calculation, the filelist shows the content of the interferometry folder where you find 10 solution files named S0_xxx to S9_xxx. S0 is the straight autocorrelogram. Autocorrelation peaks generally are embedded in noise and difficult to measure.
|
|
|
In order to highlight the peaks clearly, the autocorrelogram is processed by subtracting a median mask using growing kernel (3x3, 5x5 ....). Files S1 to S9 are the result of this treatment. The problem is that the autocorrelation peaks are strictly symmetrical and there is always a 180° orientation ambiguity. To remove the ambiguity we can try to shift and add some images or use the alternative offered by Reduc: cross-correlation
|
|
|
The crosscorrelation is another way to interpret the images of speckles. It has a main advantage because it allows to remove the ambiguity of 180 ° |
|
|
Transactions are strictly the same as for the autocorrelation described in the previous chapter. Loading the images then click Cross-Correlation. Again the FFT is used and the warning about the dimensions of the images may appear => proceed as in the previous chapter.
|
|
|
In the final calculation, the filelist shows the content of the interferometry folder where there are 10 files solutions (see previous section)
|
|
|
It remains only to measure the peak corresponding to the secondary component. It is the brightest peak (*) (*) Actually the position of the secondary should be designed by the faintest peak. The internal process of Reduc reverse the image by 180° in order to show the secondary as the brightest peak. Just a question of easiness for the user :) |
|
|
The choice of the best solutions among the ten solutions computed must be adapted to your equipment and you'll have to test. However, here is a rule of thumb that can help to begin: Smaller the sampling, greater the number of the solution. Warning: |
|
|
The measurement is the same way that you measure a double star. We can measure the two symmetrical peaks (the distance between peaks is twice the actual distance) however Reduc proposes something simpler! |
|
|
Activating the Fast Measurement Interferometry option, we can now measure the autocorrelogram with a single click!
|
|
|
A red message recalls that the function is active
|
|
|
Select the peak to be measured and then right click Reduc computes immediatly the position angle and distance of the system and inserts them into the measurement window. The measured peak must match the B component Think of deactivating the function if you measure later 'classic' images!
|
|
|
Do not hesitate to adjust the model window (yellow window) described above in the manual. By modifying the height of the horizontal line, we modify the model and the number of pixels which are taken into account during the calculation. It's better to select heights giving a symmetric shape to the model as in the examples below.
Reminder: a right click in the yellow window makes the measure |
|
|
|
|
|
|
A common way to decrease the importance of the autocorrelation central peak is to divide the power spectrum of the target by that of a nearby single star of same magnitude. The technique is powerful but very delicate to implement during the acquisition of the images. To my knowledge only one amateur uses it regularly and the routines were developped specificaly on his demand. I leave however the group of commands in the public version of Reduc. Instructions for use: |
|
(14)
There
is not a general rule, it is necessary to try the two solutions
and to keep the one that gives the best final picture.
