Changes the image color depth to 16 grays

`Ctrl` + `↑ Shift` + `2`

All hotkeys for ACDSee

General Tags or untags the image	`\`
General Increases the magnification of the current image (zooms in)	`=`
General Opens or closes the Properties pane	`Alt` + `⤶ Enter`
General Zooms the image to fit the height within View mode window. Does not enlarge, only reduces	`Alt` + `↓`
General Zooms the image to fight the width within View mode window. Does not enlarge, only reduces	`Alt` + `→`
General Toggles the zoom lock on and off	`Alt` + `\`
General to <keybs>5</keybs>: Assigns a color label to the currently selected item. Press ALT + 0 to remove a color label	`Alt` + `0`
General Opens the Edit Caption dialog box	`Alt` + `D`
General Moves the current item to a folder you specify	`Alt` + `M`
General Opens the ACDSee pro Options dialog box	`Alt` + `O`
General Moves the focus in the Properties pane to the next tab	`Alt` + `,`
General Removes currently displayed item from the Burn Basket in Manage mode	`Alt` + `Q`
General Opens the Rename File dialog box	`Alt` + `R`
General Starts or stops the Auto Advance slideshow	`Alt` + `S`
General Restores your desktop wallpaper to the settings you were using before you applied an ACDSee Pro wallpaper	`Alt` + `W`
General Removes currently displayed item from the Image Basket in Manage mode	`Alt` + `X`
General Displays or hides the status bar	`B`
General Displays the previous item in the slideshow, Auto Advance, or View sequence	`⬅ Backspace`
General Displays the previous image	`Ctrl` + `←`
General Displays the next image	`Ctrl` + `→`
General ... to <keybs>5</keybs>: Assigns a rating to the currently selected item. Use only the numeric keypad for these shortcuts. Press <keybs>Ctrl</keybs> + <keybs>0</keybs> to remove a rating	`Ctrl` + `0`
General Displays or hides headers and footers	`Ctrl` + `A`
General Adds currently displayed item to the Image Basket in Manage mode	`Ctrl` + `B`
General Opens the currently selected image in Develop mode	`Ctrl` + `D`
General Opens the currently selected image in Edit mode	`Ctrl` + `E`
General Opens the Batch Convert File Format dialog box	`Ctrl` + `F`
General Closes the current item	`Ctrl` + `F4`
General Copies the selected portion of an image to the clipboard	`Ctrl` + `Insert`
General Opens the Batch Rotate/Flip Images dialog box	`Ctrl` + `J`
General Reduces the magnification of the area inside the Magnifying Glass pane	`Ctrl` + `-`
General Increases the magnification of the area inside the Magnifying Glass pane	`Ctrl` + `+`
General Opens the Open files dialog box, in which you can select one or more images to open in View mode	`Ctrl` + `O`
General Opens the Batch Adjust Time Stamp dialog box	`Ctrl` + `T`
General Closes ACDSee	`Ctrl` + `W`
General Rotates the current image 90° counterclockwise	`Ctrl` + `Alt` + `←`
General Rotates the current image 90° clockwise	`Ctrl` + `Alt` + `→`
General Opens the Batch Edit dialog box	`Ctrl` + `Alt` + `B`
General Opens the Export dialog box	`Ctrl` + `Alt` + `E`
General Opens the previous image	`Ctrl` + `Alt` + `L`
General Sets the selected image as a stretched desktop wallpaper	`Ctrl` + `Alt` + `W`
General Opens the current image in the default eternal editor	`Ctrl` + `Alt` + `X`
General Opens the Windows Explorer context menu	`Ctrl` + `Mouse right click`
General Opens or closes the Magnifying Glass	`Ctrl` + `↑ Shift` + `A`
General Toggles full screen mode	`Ctrl` + `↑ Shift` + `F`
General Closes all images	`Ctrl` + `↑ Shift` + `F4`
General Opens or closes the Histogram pane	`Ctrl` + `↑ Shift` + `H`
General Prints all currently selected images, or all images in the current folder	`Ctrl` + `↑ Shift` + `P`
General Opens the Edit Header/Footer dialog box, in which you can specify the text to display on your images in View mode	`Ctrl` + `↑ Shift` + `Q`
General Opens or closes the Navigator pane	`Ctrl` + `↑ Shift` + `S`
General Displays or hides the Bottom toolbar	`Ctrl` + `↑ Shift` + `T`
General Sets the selected images as a tiled desktop wallpaper	`Ctrl` + `↑ Shift` + `W`
General Sets the selected images as a centered desktop wallpaper	`Ctrl` + `↑ Shift` + `Alt` + `W`
General Changes the image color depth to black and white	`Ctrl` + `↑ Shift` + `1`
General Changes the image color depth to 16 grays	`Ctrl` + `↑ Shift` + `2`
General Changes the image color depth to 256 grays	`Ctrl` + `↑ Shift` + `3`
General Changes the image color depth to 16 colors	`Ctrl` + `↑ Shift` + `4`
General Changes the image color depth to 256 colors	`Ctrl` + `↑ Shift` + `5`
General Changes the image color depth to Hicolor	`Ctrl` + `↑ Shift` + `6`
General Changes the image color depth to Truecolor	`Ctrl` + `↑ Shift` + `7`
General Toggles the exposure warning on and off	`E`
General Displays the last of your selected items, or the last item in the current folder	`End`
General Closes View mode and returns to the previous mode	`⤶ Enter`
General Closes current dialog box, or closes View mode and returns to previous mode	`Esc`
General Toggles full screen mode	`F`
General opens the ACDSee Pro Help file	`F1`
General Opens the Rename file dialog box	`F2`
General Refreshes the View mode window and reloads the current image	`F5`
General Displays the first of your selected items, or the first item in the selected folder	`Home`
General Opens the Open files dialog box, in which you can select one or more images to open in View mode.	`Insert`
General Toggles the pan lock	`L`
General Removes the current item from your hard drive	`↑ Shift` + `Del`
General Opens the current file in the default system application or opens a dialog box where you can select an application	`↑ Shift` + `E`