This menu groups operations which apply only to
images.
New
Makes a new image. Region on Image 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.
Convert to Image
Try to make an image out of anything.
Format
Switch between the various precisions.
Header
Try to change or examine the image header in
various ways.
Cache
This caches an image in RAM. Use this to save
the results of a long computation.
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.
Band
Extract/insert/delete image bands. Use ToDimension to change image bands into a horizontal
or vertical dimension. Use To Bands to compress the
horizontal or vertical dimension into bands (small
images only!).
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 bandwise,
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, or chop an image into a set of
tiles.
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.
Test Images
These items make a variety of useful
testcharts for evaluating spatial response and
colour.