How do I change the DPI to 300 for a photo to be mailed

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jeanne
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How do I change the DPI to 300 for a photo to be mailed

Post by jeanne » Fri Jan 09, 2015 5:46 pm

The title pretty much says it - I'm dealing with someone who needs 300 dpi or higher for the photos I send her and I have
no idea how to do it.
Thank you,

Jean

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Jay Cline
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Re: How do I change the DPI to 300 for a photo to be mailed

Post by Jay Cline » Fri Jan 09, 2015 6:15 pm

If you don't have an image editing application such as Photoshop you can open your image in Preview, go to the Tools menu and drop down to Adjust Size. See the image below and uncheck where is says resample image. Change the resolution to 300 and save.
Be sure to use original, full-size images and don't try to make a small image larger by increasing the dpi, it'll look really bad. Any reputable print/graphics shop should be able to do this for you.
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jeanne
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Re: How do I change the DPI to 300 for a photo to be mailed

Post by jeanne » Fri Jan 09, 2015 7:53 pm

I'm afraid I don't even know where Preview is and I can't find the tools menu either. What application are you in?

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Jay Cline
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Re: How do I change the DPI to 300 for a photo to be mailed

Post by Jay Cline » Fri Jan 09, 2015 10:00 pm

Look in your applications folder. You'll find an application called Preview.
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JerryFreilich
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Re: How do I change the DPI to 300 for a photo to be mailed

Post by JerryFreilich » Sat Jan 10, 2015 9:13 am

The question also raises the point that some photos may not have been taken at 300 dpi, which is a pretty high resolution image. For someone new to the whole issue of scaling and photo resolution, this may be introducing more complication than you want to hear right now. If the whole goal of the 300 dpi was to send someone a very high quality image... you can do that, as Jay says, in Preview. If you are emailing that image, it can also be done by choosing the little size selector pull downs in Mail. Using the "Actual Size" or "Large" tabs would send such a higher-quality image.

The more complicated explanation here is that if a photo was taken at lower resolution than 300 dpi, you cannot make it be 300 dpi by using software settings. If the fine level detail was not in the original image, you cannot add extra pixels to make it more detailed. Hope this hasn't merely confused matters.
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Stephen Hart
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Re: How do I change the DPI to 300 for a photo to be mailed

Post by Stephen Hart » Sat Jan 10, 2015 9:44 am

There are many complex explanations of this issue you can find on the web if you want to really dive in.

Dpi means dots per inch, and it's a measure of what a printer can do, not what's in a digital image file. The original file is measured in pixels in each dimension, or megapixels (length times width). For example, 3888 × 2592 (10.1 MP) or 5472 × 3648 (20.0 MP) from my current camera and 2816 × 2112 (5.9 MP) from my older camera.
All inkjet printers, from home models through "photo" models to professional ones do their own calculation. 300 dip is just a standard for inkjet. 600 dpi is a standard for black and white laser printers.

Everything depends on how large you are printing. Even low-resolution files can produce good 4x6 prints.
But the result also depends on the processing in the printer. I've gotten superb 20" x 30" prints from Apple from a 2816 × 2112 (5.9 MP) image. That's because they use a very high-end printer.
"Design is not just what it looks like and feels like. Design is how it works."
Steve Jobs

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Stephen Hart
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Re: How do I change the DPI to 300 for a photo to be mailed

Post by Stephen Hart » Sat Jan 10, 2015 9:45 am

Jay Cline wrote:Look in your applications folder. You'll find an application called Preview.
Or hit command space and start typing "preview." Spotlight will find the app.
"Design is not just what it looks like and feels like. Design is how it works."
Steve Jobs

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