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Select Menu

Selecting a rectangular region.

The rectangular selection region, or the "image rectangle", is used throughout Lispix to crop images and data cubes, and to select the area for showing image data.  The rectangle can be set with the mouse by dragging (use Draw Rectangle below), or with the keyboard, using one of the Select menu items.

  • Draw rectangle - select a rectangular area of pixels by dragging the mouse from one corner of the rectangle to the other.  (New - 3/05 - rectangle confined within image boundary.)
  • Adjust rectangle (new 12/00) - Turns the new drag feature back on.  The drag feature is turned off by some of the tools that offer their own drag functions.
  • Click single pixel - Select a single pixel by clicking on it.
  • Select ALL - Select entire image, whether it is visible in the window or not.
  • Select all in window - Select all of image visible in window.
  • force to square - Moves lower right corner of rectangle so that it becomes a square with sides equal to the smaller of the rectangle height or width.
  • Set by typing - Set rectangle by typing in coordinates of diagonal corners, or center coordinates and radius.
  • Clear selection - Clears the image rectangle. Clears the :mlx parameter :image-rectangle by making it nil.  Many operations will work on the whole image if the rectangle parameter is nil. Also stops drawing the rectangle on all open images.
  •  -
  • Crop image to rectangle - Makes new image of what is inside the rectangle, copying it to a new window and rescaling.  Use shift key for all images.
  •  -
  • Set Rectangle Color - The rectangle will be drawn in the current color of the Color menu.
  • Show Rectangle - Draws rectangle on the front window - usually some window other than on which the rectangle was selected.
  • Hide Rectangle - Rectangle is no longer shown on front image (shift key for all images).  Does NOT clear the selection - the coordinates remain in the image-rectangle parameter.
  • Show Rectangle Info - Shows rectangle area, size and coordinates in a dialog.
  • image rect overlap - Prints 'and' and 'or' of selected image dimensions. Assuming the upper left corners of all images to be alligned, gives lower right corner coordinates of image that would be contained in all the images, and the lower right corner of image that would contain all the images.
  •  -
  • mask from rectangle - Uses current image rectangle. Makes a mask image the size of the front image with the area designated by the :image-rectangle as white, everything else black. Use Draw rectangle to set the rectangle.
  • Mask from parallelogram - Now incorporated in Make Mask.
    • Uses a parallelogram, which you draw:
    • Draw a parallelogram on an image window.  (Works only on the front image window.)
      (1) Draw a line. (this is first, fixed side of parallelogram.)
      (2) Draw another line out from the first line. (This will draw the other three sides of the parallelogram.)
    • Will make a mask image the size of the image that is all black,
      except for the parallelogram, which will be white.
    • Useful for making masks for '2&3 variable -> scatter plots -> traceback'.
  • Help - masks - Shows documentation page for masks.


New 12/04:  After drawing the rectangle, you can move it by clicking anywhere within the rectangle and dragging.  If at a later time the drag feature does not work, it can be turned on again using Select / Adjust rectangle.  So far, adjustment consists of translation - you cannot yet change the size of the rectangle by dragging one of its sides or corners.

The image rectangle (shown below in red) is a global parameter, that is it can be set using any image, and used on any other image.  It corresponds to pixels, i.e. it zooms on the screen along with the image.


Cropping images is done by setting the image rectangle: Select / Rectangle / Draw (etc.) and then using Select / Rectangle / Crop Image to rectangle, which makes a new image that is the size of the rectangle.

 To make images of a specific size, set the rectangle with one of the Select / Rectangle menus. Use Size! button to move the image into view if the offset (inherited from the parent window) has moved it off the window.

The rectangle can also be set using the circle in the Circle Tool:


Image rectangle in red.

Cropped image.

Rectangle information.



You can also cut and paste the information from the dialog.