Auto color adjustment (Ctrl+K)

For best results, adjust image horizontal and vertical alignment before using 'Auto color adjustment'

When taking separate left/right images for a stereo-pair, the exposures may not be matched for a variety of reasons.
SPM's 'Auto color adjustment' uses histogram-matching to try to adjust the color/brightness of the images.
By default, the left image is taken as reference but there is a menu option to make the right image reference.

Simply click the toolbar button, press Ctrl+K (for 'Kolor' adjust) or choose 'Adjust/Auto color adjustment' from the menu.
If you are not satisfied with the result, you may choose 'Edit/Undo' from the menu.