LAF:Properties Panel

The Properties button at the top of the Load Analyze (LAF) panel calls up the LAF:Properties panel. This panel can be used to reduce the data set to preserve space in shared memory.

File Name

The File Name is the name of the currently selected file. If it is not the file that you wish to load, select a different file using the file list and/or the "Dir" and "File" fields in the main panel.

Slider Control Buttons

The Slider Control buttons control the context of the three sliders -- Start, Increment, and Number -- immediately below it.

Vol Button
The Vol Button allows you to choose which volumes to be loaded.

Z Button
Z Button allows you to choose which slices in a volume to be loaded.

Y Button
The Y Button allows you to choose the length of each slice to be loaded.

X Button
The X Button allows you to choose the width of each slice to be loaded.

Start Slider

The Start slider specifies the first volume, slice, or pixel to be loaded.

Increment Slider

The Increment slider specifies The increment between successively-chosen volumes/slices to be loaded. For instance, if you only wanted to load every third slice, you would select the Z Slider Control button and set the Increment slider to 3.

Number Slider

The Number slider controls specifies the number of volumes, slices, or pixels to be loaded. For instance, if you only wanted to load the first 16 slices of a 32 slice data set, you would select the Z Slider Control button and set the Number slider to 16.

End

The End value tells you the number of the last slice or volume you will be loading.

Bits Per Pixel

The Bits Per Pixel value gives the number of bits per pixel in the image. This number is taken from the image header and is either 8 or 16.

16 to 8 bit Checkbox

If the image to be loaded has 16 bits per pixel (this data will be displayed in the Bits per Pixel value, above), you can load the image as an 8 bit image by clicking on the 16 to 8 bit check-box.

The advantages of loading a 16 bit image in 8 bit format are several. Firstly, an image converted to 8 bit format, when loaded, takes up only half as much space as a similar 16 bit image. Furthermore, the hardware on which VIDA runs can only display 8 bits worth of color, so an 8 bit image will look, on screen, exactly like its 16 bit counterpart.

However, there is some data loss when an image is converted from 16 bit to 8 bit format, so it is often advantageous to leave an image as 16 bit data if you plan to take measurements on its pixel values.

Scale Max and Scale Min Sliders

The Scale Max and Scale Min sliders control the range of the pixel values of the image to be placed into shared memory.

In the image file, the pixels that comprise the slices have values between 0 and 255 (for an 8 bit image) or between -32768 and 32767 (for a 16 bit image). When the slices of the image are displayed, these values are mapped by VIDA to the colors contained in the color scale and are then displayed on the screen in the appropriate colors.

By changing the Scale Max and Scale Min values, you change the value of the pixels in the image, thus changing their color when they are later displayed. Decreasing the Scale Max value causes pixels with values greater than the new Scale Max to be given the maximum pixel value in the image, and the pixels that originally had values in the rest of the range (from the Scale Min to the new Scale Max) to be mapped into the original range.




Copyright 1994-99 Division of Physiologic Imaging, Dept. of Radiology, Univ. of Iowa


VIDA Directory | NLM Homepage | DPI Homepage | Contact Us | Search