Tasks

5.8 Tasks

This menu repeats many items from other menus, but tries to group them by tasks they are useful for, rather than by function.

5.8.1 Capture

This menu groups operations which are useful in capturing images, or for the initial processing you might want to do to an image captured from another program.

Capture Video Frame: This menu item will currently only work on Linux machines with a compatible video4linux capture card. See §3.1.1 for notes on how it works.
Smooth: Use this to remove texture from images. It’s handy in conjunction with Flatfield.
Flatfield: Use this to correct homogeneity. Select an image of a piece of white (or mid-grey) card, then select the image to correct, then click Flatfield. Use Smooth to renmove texture from the white card if necessary.
You can select a single white and a group of images to correct a large set in one step
White Balance: Use this to move the white point to make an area of the image you know to be white, white. Mark a region on an image, enclosing a patch you know to be white. Select the region and the image and click on White Balance.
Find Colour Calibration: Use this to colour calibrate an image. Drag a region enclosing an image of a Macbeth Color Checker Chart and click Find Colour Calibration.
Apply Colour Calibration: Use this to apply the transform calculated by the previous item to another image. Select the calibration object, select the RGB image you want calibrated, and click Apply Colour Calibration.

5.8.2 Mosaic

The items in this menu are discussed in appalling detail in Chapter 3.

One Point

Join two images left-right or top-bottom with a simple translation. Mark a point on each image to be joined (open image view window, Ctrl-left-click, drag to position), then click on the mosaic button. The operation performs elaborate tie-point adjustment, so your he RGB ch direction; hold down Shift as well to move a screenful at a time; hold down Ctrl as well to jump to the extreme edges of the image.

You can also drag with the middle mouse button to pan around the image. Use the mousewheel to pan up and down, hold down Shift and the mousewheel to pan left and right. Use Ctrl and the mousewheel to zoom in and out.

Use the View menu to add extra elements to the window. You can turn the status bar on and off, and you can add a display control bar, a paintbox and a set of rulers to the window.

Figure 4.1:

The display control bar

If you select View / Toolbar / Display Control, nip2 will add a bar to the top of the window which you can use to change the contrast and brightness of the image you are viewing. The left-hand slider and text box set the gain for the image: each pixel is multiplied by this amount before display. The right-hand slider and text box set the offset: each pixel has this value added to it before display. This is useful for boosting the brightness in dark areas of images.

Figure 4.2:

The display control bar menu

If you click the left mouse button on the arrow to the left of the display control bar, nip2 pops up a menu of useful display functions — see Figure 4.2.

Scale searches the area of the imag