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5.5 Image

This menu groups operations which apply only to images.

`New Image`
  Makes a new image. `New Region` makes a new region, arrow, guide or mark on an image. It's usually easier to open a viewer on an image and Ctrl-drag.

`Number Format`
  Changes the bit depth of the image.

`Band`
  Extract, insert and delete bands from an image.

`Crop`
  Crops an image. It's often easier to drag out a region. This menu item is only really useful for cropping large groups of images.

`Insert`
  This takes two images and pastes the smaller into the centre of the larger. The two images have to have the same number of bands. If you open an image viewer on the large image, you'll see an area which you can drag around to set the exact insert point.

`Select`
  Draw elipses and polygons on an image. Useful for selecting defined areas.

`Join`
  Use to join two images together left/right or up/down. `Array` joins a list of lists of images together into a single large image.

`Tile`
  Repeat an image horizontally and vertically to make a larger image.

`Levels`
  Various tools that change the levels in an image. `Tone Curve` is the only complex one: it lets you adjust the image levels with a set of sliders.

`Transform`
  Various tools that change the geometry of an image.

  To use `Rotate` / `Straighten`, mark an arrow on an image (Ctrl-drag up and left in an image view window) along a near-horizontal or near-vertical edge. When you click on `Rotate` / `Straighten`, `nip2` will rotate the image by the smallest amount that makes that edge exactly horizontal or vertical.

  `Linear Match` takes two images and rotates and scales the second so that the images can be superimposed. Drag the tie-=points to mark common features. Use `Filter` / `Overlay` or `Filter` / `Colourize` to actually superimpose them.

  `Rubber Sheet` is useful for fixing things like lens distortion. You give `Find` two images, a reference and a distorted version of that reference, and it automatically finds a transform which will map the distorted image back on to the reference image. Use `Apply` to apply the discovered transform to another image.

`Change Header`
  This lets you change the various `informational' fields in the VIPS image header, such as origin, type and resolution.

`Make Patterns`
  These items all make useful images for you, from checkerboards to gaussian masks. `XY Image` is the most useful: you can use it to build other patterns.

`Make Test Images`
  These items make a variety of useful testcharts for evaluating spatial response and colour.

Next: 5.6 Math Up: 5. Image processing menus Previous: 5.4 Histogram Contents