View Menu

The View menu contains items that affect the look of the image, for example by manipulating the colors or cut levels, and items that give you some view of the image data, such as a graph of the pixel distribution.

Colors ... pops up a window to set the colormap, intensity, color scaling algorithm and the number of colors allocated.

Selecting a colormap from the list installs a new colormap from the relevant MIDAS colormap file. Selecting an intensity, modifies the current colormap by applying the given MIDAS intensity file. The number of colors allocated can be set with the scale widget. In this way, you can decide to use more colors for better image quality, or fewer colors, so that other applications will still be able to get enough colors. See RtdImageColors(n) for a description of this widget.

The Cut Levels item pops up a window to set the image cut levels, or the lowest and highest pixel values considered when distributing colors to pixel values.

The graph shows a plot of the pixel value distribution in the image and the scales, arrow buttons and entry widgets allow you to manipulate the cut levels and the graph. The Auto Set buttons allow you to set the cut levels by percent of pixels within the cut levels. The Set button sets the cut levels to the selected values. Reset sets the low and high cut levels to the min and max image values resp. Median Filter applies a median filtering algorithm to the image to set the cut levels. Close removes the window again. See the man page RtdImageCut(n) for more details.

The Cuts... item sets the drawing mode in the canvas to line and changes the cursor to reflect this. After the user drags out a line on the image, a popup window is displayed with a graph of the pixel values along the given line

Once the spectrum graph is displayed, dragging the line or resizing it updates the graph with the image values under the line. See RtdImageSpectrum(n) for a description of this widget.

The Pick Object... item pops up the Pick Object window, allowing you to select an object in the main image. Once an object is selected, statistics are displayed about the object, including the center coordinates in image pixles and world coordinates (if supported by the image), the object size and rotation, calculated using a FWHM algorithm. The selected object is marked by a blinking cross in the image, which also shows the size and rotation of the object. You can also zoom the small image in and out to get a better view of the object.

This widget is described in RtdImagePick(n) .

The FITS Header... item displays the FITS file header information in a text window, in the cases where the image was loaded as a FITS file (For real-time images, the header is normally empty, since the necessary information is received via socket from the rtdServer).

The Pixel Table item pops up a window displaying a table of pixel values while tracking mouse pointer motion events.

The row and column headings are the X and Y coordinates in the raw image and the table items are the image pixel values at the given coordinates. Note that normally, the origin is at lower left in the raw image. This changes when the image is rotated or flipped. The table is constantly updated when the mouse pointer is moved over the image. See RtdImagePixTable(n) for more details.

The Magnification item brings up a new menu which allows the user to select to zoom ratio for the RTD.

The three toggle buttons at the bottom of the View menu are self-explanatory, allowing the user to turn certain components of the RTD on or off.