Sunday, November 14, 2010

IPhoto sets all photos at 72dpi but I am entering a contest where I need to send 300dpi images. How do I ...?

do this? iPhoto seems to offer no option for changing the dpi. Also, doesn't 72dpi lower my print quality?IPhoto sets all photos at 72dpi but I am entering a contest where I need to send 300dpi images. How do I ...?
72dpi is screen resolution. I got rid of iPhoto years ago I hated the way it keeps making copies. iPhoto stores the images at 72dpi, but when it sends them to your printer it will alter the resolution to get the print size.



If you have Photoshop you can demonstrate this quite easily, go into Image%26gt;Image Size. In the dialogue box that opens make sure the 'resample' box is UNchecked, now play around with the resolution numbers and you will see the print size (Height and Width) alter. If you check the 'resample' box it will keep the original dimensions but interpolate the Image and the file size will alter.



You will hear a lot about 'the minimum resolution for print is 300dpi' what nonsense! It's something to aim for, but is definitely not a minimum. It shows that even some 'professionals' often don't fully understand the relationship of resolution with print size.



The best resolution you will get from film printer paper for instance (the epitome of quality) is 200dpi, scan them at higher resolution you will get a bigger file size, but importantly no more detail. Most DSLR's (including Canon, Nikon etc) native resolution is 240dpi. This is just what the images are stored as, and can (and probably will) be altered when you come to print.



ChrisIPhoto sets all photos at 72dpi but I am entering a contest where I need to send 300dpi images. How do I ...?
Buy a ';camera';
It actually doesn't matter. It depends on your camera's resolution, while iPhoto can specify Dots-Per-Inch (DPI) it is ultimately your image's resolution that will take into account. Check the contest's submission guidelines, when they are talking DPI they should specify print size, so if they want an 8X10 print at 300dpi make sure that your image is at least 2400X3000 pixels (you obtain image resolution by multiplying size times DPI)

Other resolutions common are:

4X6 = 1200X1800 pixels

5X7 = 1500X2100 pixels

In a nutsell, if you took your image with a digital camera with enough megapixel resolution you should be able to provide sufficient DPI for those print sizes, if not there are image upsize methods that do not diminish image quality such as interpolation that will enable you to meet those DPI requirements. If you use Adobe Photoshop, you can look programs such as Genuine Fractals or Extensis pxl SmartScale.
Yes, 72 DPI is the default for image resolution on computer monitors.



300 DPI is the minimum setting for making photographic prints.



I got rid of my Mac's over four years ago, so cannot comment on iPhoto with any accuracy.



I suggest you start by downloading Adobe Photoshop Elements v. 4 and use it to modify your images instead of iPhoto.



You didn't mention what camera you are using. Depending upon the camera, JPEG images are saved as 72 DPI, 150 DPI and 300 DPI .. on the camera.
Send your original file, not something you pull off of IPhoto.

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