This is a quick summary of image window/level (brightness/contrast) adjustment changes introduced in recent Slicer Preview (formerly known as “Nightly”) releases.
- Improved automatic window/level algorithm
Images that do not contain preferred window/level information are displayed with automatically computed values. The complex automatic computation algorithm that had been used in Slicer worked marginally better for some images, but sometimes generated too bright images and overall the results were somewhat unpredictable.
The algorithm is replaced by a simpler one, which adjust the window to display intensity values between 0.1 and 99.9 percentiles.
- Improved manual window/level adjustment
New mouse mode is added for window/level adjustment. This prevents accidental modification of window/level when interacting in slice views and allows new window/level adjustment methods. Click on the corresponding icon on the toolbar to activate the new mode. The icon consists of color and grayscale gradients and a mouse pointer:
Window/level setting options:
- Click-and-drag adjusts window/level (same as before)
- Ctrl + left-click-and-drag sets optimal window/level for the selected region. Pressing Escape or right-click during the drag cancels the operation.
- Double-click resets window/level (using automatic window/level algorithm, for the entire image)
Region-based auto window/level example: