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9. Image display

9.1 Colors and grey levels

When the image is loaded into memory, it is also displayed in an X window. Before or after loading you can choose either grey level or color coded intensity display. You choose the pallete by pressing either Grey or Color button in the image window. If you want to save this setting as the default mode for the next time when you invoke fitsblink, go to the Astrometry menu and choose the Settings item. Although white stars on black background are ``natural'', you may prefer to set the inverse mode (black stars on white background) or color mode in which you spot nebulosities more easily. If you have only an 8-bit display and you already run some colorful program when you invoke fitsblink, the color pallete may be limited and you may see images displayed in some funny colors.

9.2 Moving the cursor

You can move the cursor over the image either by mouse or by using cursor keys. The latter way is useful when the original image has more pixels than the window where it is displayed. If you use mouse to move the cursor, some of the pixels will be skipped. You can get around this by using cursor keys on your keyboard. In this way you can examine the values of individual pixels.

9.3 Adjusting grey level mapping

If you are not happy with the color or grey level settings which were set automatically when the image was loaded, you may want to adjust them manually. You can do this by holding the left mouse button on one of the points in the Grey level correction window and dragging it to a desired position. Typically, the two points between which the curve jumps from zero to the maximum value are very close together. For fine adjustment you should zoom the curve by clicking on arrow buttons below the window. Press the right mouse button for quick zoom, middle mouse button for moderately quick zoom and left mouse button for slow zoom. Pressing the right mouse button on the third arrow is what you usually need.

There is also a possibility to change one parameter for auto-level routine. You can find the input field for this parameter in the Display folder of the Settings window.

9.4 Resizing the blinker window

You can resize the blinker window to some limit in the usual way as it is done in X-Windows. If you want to set the new window size as a default value for the future invocations of fitsblink, just open the Settings window and press Save. Note that you also save all other parameters when you do this.

9.5 Zooming and panning

For images much larger than the image window it is sometimes desired to enlarge the view so that a smaller portion of image will occupy the image window. It is very easy to enlarge the image. Just press the middle mouse button and extend the rubber band to contain the area you want to see enlarged. All other images with the same dimensions which may be loaded at that time will also be enlarged so that the blinking may be performed also at this level of magnification. You will see a bright rectangle inside the darker rectangle which is located just below the image. You can move the bright rectangle inside the small one to display different parts of image.

If you want to enlarge the view to the whole image, just press the Full button.

next up previous contents
Next: 10. Markers Up: Fitsblink 3.13 user manual Previous: 8. Erasing an image
Jure Skvarc