Images

An image is a two-dimensional array of pixels. The value of each pixel represents the intensity and/or color of that position in the array. Images of this form are known as sampled or raster images, because they consist of a discrete grid of samples. Such images come from many sources and are a common way of representing scientific and medical data.

Working with Images

The following routines are used to display and control images.

TV Procedure—Displays images on the image display.

TVSCL Procedure—Scales the intensity values of the image into the range of the display device, and then displays the result.

TVRD Function—Reads image pixels back from the display device.

TVCRS Procedure—Manipulates the image device cursor. TVCRS allows the cursor to be enabled and disabled, and allows it to be positioned.

TVLCT Procedure—Loads user-defined color table into display device.

LOADCT Procedure—Loads predefined color table into device.

These routines are described further in this chapter, and also in the PV‑WAVE Reference. Many other routines that are useful in viewing and processing images are also introduced in this chapter, such as REBIN, CONGRID, SMOOTH, HIST_EQUAL, MEDIAN, CONVOL and many others.

In addition, most plotting and graphics routines can be used with images. These routines are described in Displaying 2D Data and Displaying 3D Data. For example, you can overlay an image on a contour plot by combining the output of the CONTOUR and TV procedures. Or, the CURSOR routine, which is ordinarily used to read the position of the interactive pointer device, can be used to determine the location of image pixels.

Version 2017.1