Meade Autostar Image Processing For Windows Version 3.
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LIMITED WARRANTY LIMITED WARRANTY. Meade Instruments warrants that (a) the SOFTWARE will perform substantially in accordance with the accompanying written materials for a period of ninety (90) days from the date of receipt, and (b) any hardware accompanying the SOFTWARE will be free from defects in materials and workmanship under normal use and service for a period of one (1) year from the date of receipt.
Autostar IP Contents Introduction ......................................................................................................................................................... 7 A Note on Accuracy ....................................................................................................................................................... 7 System Requirements .................................................................................................................................
Autostar IP Contents Flip Image ....................................................................................................................................................................... 21 Rotate Image.................................................................................................................................................................. 21 Resample ..........................................................................................................................
Autostar IP Contents Image Processing Basics........................................................................................................................................... 39 Bibliography ...................................................................................................................................................... 41 Glossary ....................................................................................................................................................
Autostar IP Introduction Welcome to Meade Autostar IP astronomical image processing software. Now you can perform many of the same image processing tasks that a professional astronomer would do on a large institutional computer. With Meade Autostar IP you can: • Enhance high resolution images using advanced image processing techniques. • Determine stellar magnitudes directly from electronic images, and a number of other powerful features.
Autostar IP 1. Installation Autostar IP is installed as part of Meade’s Autostar Suite. If you have not yet installed the Suite, consult the quickstart instructions for the complete instructions. Typcially, when the Autostar Suite CD ROM is inserted in your computer it will automatically begin the install process. If your system has “autoplay” disabled, click on START, then click on RUN. When the run dialog box appears, type A:SETUP then press Enter.
Autostar IP 2. Features Tool Bar Autostar IP's Tool Bar gives you immediate access to image files to perform complex image processing with the click of a button. Status Bar Autostar IP's "live" Status Bar constantly updates the coordinate display of the image, and the pixel value (Dn.) of the image, as well as the local time. The Status Bar can also be customized under the Preferences command under the File menu. Menu Bar The familiar Windows Menu Bar gives you access to every function of Autostar IP.
Autostar IP 3. File The file menu contains a number of commands for opening and closing image files, and printing images.
Autostar IP Regardless of the file type, the image data will be converted to 16 bit integer data. This assures that high precession is maintained throughout image processing. If the image is an RGB color image, you will be prompted as to which color plane you wish to load. The following dialog will appear: If you select Load As Color Image, the program will load all three color planes and display the image.
Autostar IP Although the display shows only 256 levels, all of the image data are retained and processed by the program. Whenever you perform a processing step, you are given an opportunity to rescale the display data. The scale command, also allows you to rescale the image any time you desire. When prescaling an image, a histogram is constructed that shows the distribution of the data contained in the image.
Autostar IP Save As Fits Image Displays the Save As dialog box and allows saving the current image data in a floating point FITS formatted file. This method of saving insures that all of the information in the image is maintained. This is the format recommended for keeping archival copies of your image data. To save a file: - Select the directory and filename from the list boxes OR - Enter the desired filename in the Edit box.
Autostar IP To alter the print setting on a printer, highlight the printer in the Installed Printers window and select the Setup button. The printer’s control dialog will open an allow you to modify its settings. Finally, if the desired printer is not the systems Default Printer, user the Set Default Printer button to assign it as the system default. Remember this change will also affect any other program started after the change has been made.
Autostar IP 4.View The View formatting section allows you to modify how the image data is presented on the display in a number of ways. You can lighten or darken an image, change its contrast, or run a number of sophisticated image processing functions to bring out or suppress subtle details contained in the image. You can change the size of the image, tint its display palette or annotate it. All of the functions in the View menu affect only the image display, not the actual image data.
Autostar IP Setting the Brightness control to values greater than zero brightens the image, while values less than zero will darken it. Generally, you must use both the contrast and brightness controls together to achieve the desired results. The Linear function sets a straight line transformation that resets the contrast and brightness values to 1.0 and 0.0 respectively.
Autostar IP useful for delineating areas of similar brightness to enhance the overall shape of an object such as a comet or nebula. Before committing to the scaling function that you have selected, you can Preview the image by pressing the Preview button, you then have the option to select OK , Cancel , or try another scaling function.
Autostar IP The Pseudo button constructs a pallet that contains red, green, and blue values for a generic 8 bit color image. There are two scroll bars on either side of the palette display. The uppermost scroll bar changes the starting color of the palette, while the lower one changes the width of the palette. Moving the upper scroll bar to the right has the effect of shifting the colors to the right, moving to the left moves the colors to the left.
Autostar IP 5.Tools The Tools section allows you to examine the image data a number of ways. You can examine the image header information, magnify close up sections of the image, view brightness distribution or examine individual pixels. All of the functions in the Tool menu are for analysis and do not affect only the image display, or image data.
Autostar IP Information Displays general data about the current image, such as, size, scale factors, date of image, location, etc.. Most of this data is a permanent part of the image and can be found in the headers of the various formats. Only the size and bits per pixel values are saved in the BMP format. The FITS and TIFF formats save all of the information. The Scale Factor and Zero Offset fields contain the factors used to convert the image from the orignal data to an 8 bit image.
Autostar IP 6.Process The Processing section allows you to modify the actual image a number of ways using advanced image processing commands. Since the commands change the actual image data, this menu section features an UNDO command that will allow you to restore the image data to the its state prior to the previous command.
Autostar IP function properly. To preclude these problems, the contents of the buffers are destroyed before the rotation takes place. You should then copy the rotated image into the desired buffer(s). After the command is complete, the newly rotated image is automatically copied into Buffer A. Resample The Resample command changes the actual size of the image. This allows you to make an image larger or smaller.
Autostar IP The Normal button constructs a filter that does not alter the original image when the convolution process is started. This allows you to reset the kernel to a normal starting point when you are constructing your own kernels. The Smooth button builds a kernel that subtly blurs the image, reducing the effect of any noise that may be present in the image. Lowering the value of the center number in the kernel increases the smoothing effect. While increasing the value reduces the effect.
Autostar IP remove them. When you select this command, a dialog box will appear. This dialog allows you to set how aggressively the program hunts for bad pixels. The smaller the threshold number you supply, the more aggressively, the filter will act. Add Noise This command can be used to make cosmetic improvement to an image’s appearance. Adding a small amount of noise can cover up minor defects.
Autostar IP Linear scaling performs the following transformation: Final Pixel = (Pixel – Min.Value) * Scale Factor If the Final Pixel is greater than Max. Value, the Final Pixel is assigned the Max. Value.
Autostar IP When the command is complete, the number of colors that were found and the number of colors used in the resulting image are displayed. You should modify the number of Quantum Levels (in the RGB Merge dialog box) so that the two values are fairly close together. Generally, finding 300 to 400 colors results in the best image.
Autostar IP 7. Image Utilities The Image Utilities dialog box can be displayed by moving the cursor over the desired area of the current image and either clicking the left mouse button or by depressing the left mouse button, drawing a rectangle, then releasing the button. Clicking on a point in the image will enable the Set Distance Ref. function, drawing a rectangle enables the Rescale Size and Crop Image functions.
Autostar IP Set Reference Magnitude To calculate the magnitude of any object in the current image, you must first select an object whose magnitude is already known. Draw a selection box around the object. Then select the Set Reference Magnitude function. The following dialog will appear. All magnitude calculations in Meade Autostar IP are based on a technique called Aperture Photometry.
Autostar IP Photometry Cursor Profile Line Pixel List Area Mag/Centroid Area The Utilities Box is displayed when the left button is released. Now choose the Determine Magnitude function. You should pick a well defined object, such as a star, whose values are below the maximum set by the size of the data format. A warning message will be displayed if the selected region contains any pixels that are at the maximum.
Autostar IP This dialog show the result of your magnitude determination. Not only is the magnitude displayed, but the error of the measurement and other pertenant information is displayed. If Auto Log Magnitudes is not set, you can still write the results to the log file by clicking on the Log button. Image Statistics The Image Statistics function is similar to the magnitude functions except that it displays only the the statistical information about the selected region.
Autostar IP If the Line Profile button is selects, the diagonal line drawn through the Photometry Cursor indicates which pixels will be graphed by the Draw Profile command. Other choices are the summation of the rows, average of the rows, summation of the columns or average of the columns. If the Scaled Values box is checked, the screen’s display values are used, otherwise the image pixel values are used to generate the profile.
Autostar IP Edit Log File The Edit Log File command opens the current log file for editing with either wordpad or notepad. This allows you to add annotations to you log file as you work though and image, or to remove unwanted data that may accidentally have been written to the file. The sample below shows what a typical log file might look like.
Autostar IP 8. Group Operations The Group Operations menu contains commands that will allow you to process groups of files simulaneously. There are many tasks such as calibration, image combination, alignment and filtering where the same task may need to be done to a whole collection of images. The ability to operate on groups of images is one of the keys to making Autostar Image Processing the most convenient Windows image processing system.
Autostar IP Copy The Copy command will duplicate all of the files in the list. The new file have named that begin with the phrase "Copy_Of_”. Often, you do not want to operate on your original data, this makes it easy to create backup copies to work on. Copy will also change your group list to point to the copies as a side effect of this operation. Examine The Examine command allows you to quickly flip through, inspect and analyze a group of images.
Autostar IP The program will go through all of the images an shift them so that they will be aligned on the select star. After the the images have been aligned, a proof image will be created by averaging together all of the images in your group and displaying the results. It may take a couple of interrations to get all the images to line up if you are working in a crowded star field. The technique will work best if the alignment star is in a relatively isolated portion of the image.
Autostar IP The center coordinates of the locator boxes are shown in the window at the top of the dialog. Additionally, you can change the aperture and annulus of measurement. If you check the Recenter and Track box, each object will be recentered in each succeeding image. This allows you compensate for slight shifts of the telescope between measurements,. Additionally, for aligned images, it will allow you to track a comet or asteroid as it moves through the field of view.
Autostar IP 9. Options The Options menu contains a variety of commands that are useful in setting up or optimizing your display for the current task at hand. Night Vision The Night Vision command changes all of the standard system colors to shades of red to help maintain your eyes adaptation to the dark. This is useful if you are using the program during actual observing session in the observatory or in the field. After selecting this option you should also lower the brightness on your monitor.
Autostar IP Grayscale Palette and Standard Palette The Grayscale Palette and Standard Palette commands are used together to optimize your systems' ability to display gray scale images. If you are running in a standard VGA display mode, these commands will be enabled. Since these commands are not required in other display modes, they will appear disabled.
Autostar IP Appendix 39 Appendix A Image Processing Basics Image processing allows you to modify the appearance of an image by applying various types of filters, scaling options or transformations. The simplest type of processing is linear scaling. With linear scaling, one pixel from the source image is multiplied by a scale factor, then an offset term is added. The original pixel value is then replaced with the resulting value. This process is repeated on each pixel in the image.
Autostar IP Appendix 40 center pixel value is replaced with the new result. This process is then repeated for every pixel in the image. There are many different kernels that you can create that give various results. Meade Autostar IP provides several basic kernels that provide the most common functions, but feel free to experiment. There are a number of image processing books available that will describe other types of kernels.
Autostar IP Appendix Bibliography William K. Pratt, Digital Image Processing, second edition, John Wiley & Sons, Inc.
Index 42 Glossary absolute magnitude - the apparent magnitude an object would have if it were moved to a distance of 10 parsecs. angular diameter - the apparent diameter of an object expressed in angular measure i.e., deg, min, sec. aperture - the diameter of the objective lens or primary mirror of a telescope. apparent magnitude - the observed brightness of an object without any correction for distance.
