These file extensions are recognizable as graphics files and therefore Graphics Quick View is used : jpg, jpe,gif,bmp,ico,tif,tiff,png.

Zooming in/out with Numpad + and Numpad -. Numpad * - fits to the window, Numpad / - sets the original size. Also F3 zooms out, F4 fits to the window.

Tools : magnify tool – ‘z’ or F2, selector – ‘s’, hand – ‘h’.

Zooming out and in with mouse : select an area with right mouse button to enlarge it. Press rigth mouse button once to zoom out. Do rigth-left click to show the context menu.
You can also use wheels, to zoom in\out. Note, that when zooming in, then ACB tries to show the part of the image over which is the mouse pointer, so point the mouse over the area you want to zoom in, then scroll back.

Browsing – you can view next (Page Down) or previous (Page Up) image in current list. Also you can go to the first one (home) and last one (end). You can also turn on Slideshow – such a small car icon in the toolbar, or hit space. Also, in the view menu you can turn on Tile mode.

Converting. You can change light and contrast, size, type, number of colors. Note that Viewer will not prompt you to save the file. Press C.

Saving. After conversion you can save the image. Ctrl+S.

Saving as... You can convert and save image in one step. Press Alt+Shift+A, conversion dialog will appear, you can use it, you can also change the image format (jpg, tif etc...) and change the file name. After pressing OK button, or pressing Enter the image will be saved.
Note, than since version 2.0 of ACB, you can convert the image simpler, directly from the list window. Select the image file, then press Alt+Shift+A, then the conversion dialog box from the Image Quick Viewer appears, and you can change the image properties now.

Copying to the clipboard. With CTRL+C you can copy the image to the clipboard. Also you can copy just a selection – make the selection, and copy. Note that after copying, or refreshing the window the selection is no longer valid.

Pasting from the clipboard. With CTRL+V you can paste the image from the clipboard. Then you can convert it, and then save it, or copy back to the clipboard.

File operations. You can set a comment to the currently showed image (Alt+C), delete the image (Delete key), copy (F5) and move (F6) to… When you select copy to or move to you have a choice of all currently open browse windows in the main ACB window.

Notes.

You can also convert an image directly from the file window, pres Shift+Alt+A, or simply rename the file - if you'll change the extension, ACB will try to handle that (more: Smart renaming - however you'll have then less options).