Main Window - Options | Viewing - Editing                    Ctrl+J

View Window - View | Preferences - Editing                    F9



Click on the links above to view extended information on each dialog tab.



Delete the file when pressing DELETE with no selected area. Check this option to delete the file is the delete key is pressed and there is no area selected.


Automatically adjust non-square aspect ratios. If checked, images with stored resolutions having different horizontal and vertical values will be automatically scaled to reflect the non-square resolution aspect.


Show file format options when overwriting (File | Save). Check this option to make ThumbsPlus display the file format options dialog (if applicable) when overwriting an existing file via File | Save from the view window menu.


Use original JPEG quality when overwriting JPEG files (File | Save). If checked, ThumbsPlus will use the JPEG image's original quality value when saving the new JPEG file.


Disable Undo (saves memory and speeds editing). If you select this option, ThumbsPlus will not save the information necessary to undo image operations. This will speed up edit time and require less memory and temporary disk space.


Maximum memory for image undo buffers. If Undo is enabled, you can limit the amount of memory that ThumbsPlus will use for the image undo buffers. The memory buffer size entered is in kilobytes.


Autocrop tolerance. Enter a value between 0 and 250 for RGB color range matching while autocropping.



Background color for delete and cut. Click this button to select the color that will be used to fill deleted or cut areas.


Use white for bi-level images. Check this option to use white instead of black to fill deleted or cut areas in bi-level images.



Channels & Alpha


Checkerboard. Check this option to display a checkerboard pattern as the image background when viewing images which contain an alpha channel. Use the two adjacent color buttons to control the colors used to draw the checkerboard.


Solid. Check this option to display a solid single color for alpha channel image background display.


Use background color if available. Check this option to display the background color specified in the image (if it's image format supports a stored background color).


Show single channels in color. Check this option to render single color channels in the channel color rather than in grayscale. See: View Window - Ver | Canales | (Rojo, Verde, Azul) for more information about color channel display.


Disable initial alpha channel display. Check this option to disable alpha channel display when viewing images containing an alpha channel.

Note: The alpha channel display can always be toggled by selecting View | Channels | Alpha from the view window menu.



Selection Rectangle Size. (The options apply to the Keyboard Selection Rectangle command [F11])


Default. Default selection size - 1/3 image width x 1/3 image height.


Specific Size. If checked ThumbsPlus will set the selection rectangle to the specified width and height.