Each program allows the operator to get a quick look at the data and do some processing. The ST-4 and ST-6 have the same basic tools, so only the ST-6 tools will be described here. Most of the tools are under the display menu. When an image is displayed in analysis mode, data can be roughly analyzed. Any process done under display will only alter the display and not the image itself.
The operator can use the X-Hairs to find the pixel coordinates and value. The average value of all pixels in a square area can be determined with the smooth command. This program will also give a relative magnitude of the star. An accurate magnitude can be determined if the telescope parameters are modified. If the object is a diffuse object such as a nebula, the diffuse magnitude is expressed in units of mag/square arcsecond. The separation in arcseconds and degrees can be determined between two stars.
Other operations include flipping the image horizontally and vertically, and a zoom that enlarges a section of the image by a factor of four. The image can also be cropped. If the image is not at a contrast that is desirable, the contrast can be manipulated by the operator. The image can be smoothed. This is a process that removes the effects of rapidly varying pixels values. This is accomplished by replacing each pixel by the weighted average of a 3 by 3 square centered on the pixel. This can blur the details of an image, but can help bring out faint objects. A histogram can be displayed in either a text or graphical format for the ST-6. The ST-4 can only display a graphical histogram.
The ST-6 has a utilities menu that alters the image. The image should be saved before any processing is done to it. Several functions can be done here including dark subtracting, co-adding frames, smoothing, sharpening, and flat fielding. The dark subtract will remove the dark current and bias from the image. This removes background noise that is intrinsic to the chip. The co-add command allows two images to be added. This produces a third image with a better signal to noise ratio. Smoothing the image will have the same effect that it did before except now the image is permanently altered. Another form of filtering is the sharpening. This is a process called unsharp masking that brings out the details of the image. Flat fielding will remove the flat field from the image. This corrects for differences in gain from pixel to pixel and variations from the telescope. The tracklists must have been saved earlier if this tool is to be used in a track and accumulate image. Also under the utilities menu, the image can be rescaled. Cool and warm pixels can be removed.
The ST-4 allows some of these processes, but not all. Before using these commands, consult the manuals for these cameras.