How can I change image value to inches from pixels

It shouldn't be a problem.

Load the crop tool > select 'Custom' in the Crop HUD 'Aspect Ratio' drop-down > type '5' in both the 'Width' & 'Height' fields > drag crop tool to select area to crop > press 'Enter' or close the Crop HUD.

You can then export the version using the Size To: menu in the export preset dialog set to 'Fit Within (Inches)' and set the DPI to '100'. This should give you both a 5 inch x 5 inch on screen image size after export, as well as a 5 inch x 5 inch image during print or in a layout program (Pages, Word, InDesign - even in Illustrator).

Note - the '100' DPI setting can be tweaked if you know the absolute pixels per inch of your monitor screen (otherwise, 100 is a good general rule of thumb for a majority of monitors).

I hope that helps. 😉

Hi. The crop aspect ratio _has no units_. All it has are dimensions. The dimensions must be (it seems) positive integers. So if you want (for example) 4.75 x 8 1/8, you'll have to enter 4750 x 8125.

What silly about it? The aspect ratio has no units -- it's just a ratio: there is no measurement unit. It is widely accepted practice to express ratios by specifying two integers. (The other widely accepted practice is to normalize one of the intergers to "1").

One of the things many people have trouble with is that computer images _have no physical dimensions_. They are measured in pixels. Each pixel has different dimensions (and, in same cases, different aspect ratios) depending on the machine being used to display the image.

The crop aspect ratio has no dimensions at all. If you want an Image to be square, select "square" from the drop-down, or set the aspect ratio to 1 x 1. All that does is make the Image square -- it does not give it a size. You can view it (and print it) at any size you want, from very very tiny to bigger than a house (Aperture applies some limitations, because no-one uses the extremes.)