How to export images at 5x7 at 72dpi for sure?

It is very unlikely that your monitor is displaying 72 pixels per inch, so the image will appear smaller. 3.75 inches for 360 pixels coresponds to 96 pixels per inch which is much more likely.

If you chose the JPEG - Original Size preset, Aperture does not change the pixel dimensions from the original - that is unless you edited that preset to change the Size To: setting from Original Size to something else.

If you create an export preset and set the Size To: setting to Fit Within (Inches), then a combination of the Width and Height and DPI settings control the pixel dimensions. If this is what you did, then you did not really use the JPEG - Original Size preset as it was delivered by Apple.

BTW, the pixel dimensions you stated above are indeed a 5x7 image at 72DPI.

5 x 72 = 360

7 x 72 = 504

I agree with Jeffrey that you cannot determine the size on screen unless your display is also set to 72DPI. Or in Photoshop there is a View Print Size command that would do it if you properly tell Photoshop your display's true DPI ahead of time. Preview doesn't have that capability.

In fact, when using a ruler to measure on-screen dimensions, the resized images are about 5.5 inches wide, 3.75 inches tall, and 6.5 inches diagonally.

If the image has 360 x 504 pixels and the resolution is set to 72 dpi, then all should be well. Try to print your image, and measure the dimension on the paper. Or import it to PhotoShop and display the rulers, set to inches. PhotoShop will display an image with the correct physical dimensions.

Perhaps some of your images have been cropped with custom dimensions, so that it is impossible to achieve 7 by 5 inches without scaling the width and height differently. Then Aperture will export the image scaled to fit the smaller dimension, and the image will not fill the larger dimension completely. if you want exact 7 by 5 images you must take care to crop them with an aspect ratio of 7 to 5.

Regards

Léonie

Here is a screen shot of the jpeg "Original Size" edited to 7 by 5 inches, set to 72 dpi.

This will only result in 7 by 5 inches imes, if the aspect ratio (width to height in pixel) of the image really is 7 to 5. If the image has been cropped to custom dimensions the original proportions will be preserved on export.

To keep things clean, the OP should not be editing the JPEG - Original size preset. Instead a new preset should be made and named something like JPEG - 5x7_72DPI. Otherwise things will get really confusing when problems like this arise and help is requested.

You are perfectly right 🙂 - I just tried to redo what I think what demasoni has done, to reproduce the results, to understand the question, and to point out what might have gone wrong.

Your post was spot on. I should have replied to the original post as that is where my response was directed.