Resize Image On Mac Preview. Select tools adjust size to bring up the resize dialog which will allow you to resize the image. Resize an animated gif image in preview to change the size of a animated gif file in preview.
Once you ve opened the image file in preview go to the preview menu on the top left of your screen select tools then adjust size. But we have a better way. Choose percent from the pop up menu next to the width and height fields then enter the percentage in those fields.
If it opens in another application instead you can right click the image using the mouse or two finger click the image on your mac trackpad and choose to open it with the preview application.
You can change the unit that the image is resized in. Enter new values for width and height or click the fit into pop up menu and choose a size. Once preview is open proceed with the following simple directions. It supports many measurement units including pixels.