Adjusting Image Brightness and Contrast

MultiTracer automatically adjusts the brightness of images when files are loaded. However, it is often helpful to manually adjust the image brightness and contrast for optimal viewing. It should be noted that adjustments to image intensity have no effect whatsoever on the brightness or contrast of image volumes saved from MultiTracer using the "Save First Volume" or "Save First Volume As ..." menu items; they simply modify the display. for your convenience.

Brightness and contrast can be adjusted using the "Image Intensity" window. This is a tabbed window with a "Master" tab and numbered tabs for each loaded image. By default, this window is originally positioned at the lower right hand corner of the main image window after the first image volume is loaded.

• To brighten or darken an image, select the image's tab in the "Image Intensity" window and adjust the slider. Alternatively, you can enter a new scaling factor into the field labelled "Scale". Entering a new scale factor also adjusts the range of values accessible by the slider.
• To alter image contrast, enter a pixel value into the field "Unscaled values < __ are black". This value is subtracted from the raw input voxel intensity value before scaling. As the field label implies, voxels less than this value are displayed as black. Setting this value too high can cause the entire image to appear black. You may need to increase the brightness of the image when entering larger values in this field.
• To link the brightness and contrast settings of two or more images, select the tab for each image and click the "Use Master" checkbox. Select the "Master" tab and use the controls on this tab to adjust the brightness and contrast of all the images. You can use the "Add All" button on the "Master" tab to put all currently loaded images under the "Master" tab control. The "Remove All" tab returns control to the individual image tabs.

Modified: August 26, 2012