Exporting a specific size

fishnof

Welcome to the Apple user discussion forums

You do not - digital photos do not have a physical size in inches - they contain dots (or pixels)

If you want to print a 100 DPI print 2.25" x 1.875" then you would need to export a 225 x 187 pixel photo - if you want to print a 300 DPI print 2.25" x 1.875" then you would need to export a 675 x 562 pixel photo

I recommend reading this article on digital photos - especially the link mid page on +the myth of DPI+.

LN

Hi there. Professional applications like Photoshop make this much easier as iPhoto uses only pixel dimensions for its custom settings.

You will have to crop the image first using the crop tool and a custom setting of 162x135 (pixels). Then, choose File/Export and in the pop up window and then File Export from it's button bar. Choose Kind: Current and then it will export at the correct size.

As the other article explains in a convoluted manner, DPI is related to the print size - and therefore is a printer setting. An actual digital image size is measured in pixels - and Pixels Per Inch.

You can find out the pixel dimensions in iPhoto by highlighting a particular image and then pressing the 'i' button in the bottom left corner under the albums list. (Command i shows all of the metadata for the image if you want even more info)

It will show you image as, for example, 3000 x 4000 pixels. At Mac screen 'native' resolution, this image will be at 72PPI. So, you can divide the pixel dimensions by the native resolution, ie: 3000 divided by 72, gives you about 41 inches.

If you choose to print an image at 144PPI, the image natively reduces to half its size and will therefore print the 3000 pixels to fit into approximately 20 inches.

It is commonly recommended that if you are printing an image that the PPI should be at least 144PPI for reasonable quality. Magazines and professional printed items tend to require 300PPI and above for higher quality output. High quality photographic plates can often be huge files at 2880PPI for best possible print quality.

I am not quite sure what you are trying to achieve. You cannot improve an image by artificially increasing the PPI as most applications will simply double up the pixels. You need to either photograph or scan at the highest possible resolution and size down for best image quality.

I'm not sure why you cannot export at a custom size from iPhoto. You do ideally need a professional product for this sort of work. iPhoto is brilliant, but this isn't really its strong point or it's main function. In other words, you are probably trying to use the wrong tool for the job.

My advice is that if the publication IS professional, then send them the original file and let THEM resize it. It isn't really your job to do that.

I am not sure if I am supposed to make recommendations like this here, but you could try the brilliant Pixelmator software - it does many of the things Photoshop can do (and you can download a demo to try), or try http://www.pixlr.com

Forum administrators - I am not in anyway affiliated with those items, I am just trying to help!

If you want to print a 100 DPI print 2.25" x 1.875" then you would need to export a 225 x 187 pixel photo - if you want to print a 300 DPI print 2.25" x 1.875" then *you would need to export a 675 x 562 pixel photo*

iPhoto is all you need - crop to 675:563 (note - this is actually a ratio not a size even though the ratio numbers are the same as the size numbers) using the cropping tool and then export the photo as a jpeg using the size option to set the pixel size exported

LN