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NWE Help: Graphics: XV: Miscellany
NWE Home :: Help :: Graphics :: XV
Zooming
ctrl + You can Zoom In by a factor of two (or four, or eight, etc.) on any rectangular region of the image by holding down the < Ctrl > key on your keyboard and clicking the Left mouse button in the image window. A rectangle will appear, centered around the cursor position, showing you what portion of the image will be expanded. Move the rectangle as you see fit, release the mouse button, and the region inside the rectangle will be redrawn at twice its previous size. The image window should remain the same size. You can repeat this operation to zoom in by a factor of four, or eight, or whatever, as many times as you wish.
ctrl + While zoomed-in, you can Pan the image around by holding down the < Ctrl > key, clicking the Middle mouse button in the image window, and dragging it around. A rectangle will appear around the mouse, indicating where the currently-displayed portion of the image will be moved to.
ctrl + You can Zoom Out by a factor of two (if possible) by holding down the <Ctrl> key and clicking the Right mouse button inside the image window. You can not zoom out beyond the point where the entire image fills the window.
Multi-Page Documents
XV now has the ability to display multi-page image files, though currently this is only implemented for PostScript files (using the ghostscript interpreter). If you are viewing a multi-page document, a "page n of m" string will be added to the XV image window's title bar.
You can walk through the document by pressing the <PageUp> and <PageDown> keys on your keyboard (they may be labeled 'Prev' and 'Next' instead) while the keyboard focus is on the XV image window. Pressing <shift-Up> and <shift-Down> may also work.
You can also jump directly to any given page by typing ' p ' into the XV image window. This will pop up a dialog window which will ask you what page you'd like to go to.
Image Editing
XV now features a number of rudimentary image-editing tools. While it isn't about to compete with Adobe's PhotoShop anytime soon, you may still find what it does to be of some use. You now have the ability to do pixel-editing, freehand 'scribbling', line drawing, and pixel-level 'smudging'. Also, XV now supports cut, paste, copy, and clear of rectangular selections, as described in "Image Cut and Paste Commands" . Also, XV now has a 'text annotation' tool, described in "Text Annotation" .
The major weakness: the various drawing tools listed above can only draw in colors that already exist in the image. At this time, these tools (and XV) are primarily focused on the 'image editing' job, rather than on the 'arbitrary paint program' job. Needless to say, there's still a way to paint in whatever color you'd like. It's just a matter of getting the desired color(s) into the picture. The best way is probably to use the Pad command (see "The Pad Command" ).
Pixel Editing and Line Drawing
All of the following drawing commands use the concept of the 'current color'. The current color is set by using the Middle mouse button in the image window to 'pick up' the desired color.
You can edit individual pixels by doing a shift-middle-click with the mouse. (Hold a < Shift > key, and Middle-click somewhere in the image window.) The selected pixel will change to the desired color. It will probably help to zoom in on the relevant section of the image first. Anyway, if you drag the mouse around, you will be able to draw arbitrary 'scribbles' all over the image. This probably isn't desirable, so be careful!
You can also draw straight lines by holding down the < Ctrl > key along with the shift-middle combination.
Pixel Smudging
You can 'smudge' specific areas of the image by doing a shift-right-click with the mouse, in the image window. The clicked-on pixel will be replaced with the average color of the 9 pixels in the 3x3 square centered on said pixel. This can be used to manual edit out 'salt and pepper' noise. It can also be used to soften edges. As with the pixel editing tool, you can drag the 'smudger' around.
Note: This only works in '24-bit' mode. If you are viewing an 8-bit image, it will be automatically converted up to a 24-bit version of itself.
Note: While this tool is similar to the Blur and DeSpeckle algorithms, those algorithms operate on every pixel in a rectangular region, whereas this tool operates only on those pixels that you click or drag on.