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How do I take 300 dpi photos with my iPhone 4s? And how do I export them to my MacBook Pro at 300 dpi to use as I want to print photos.

How do I take 300 dpi photos with my iPhone 4s?

And how do I export them to my MacBook Pro at 300 dpi to use as I want to print photos.


I have been using the standard camera on the iPhone and require 300 dpi to create photo books as the photos are resized according the layout.


Your time and assistance in appreciated.

Thanks

iPhone 4S, iOS 6.1.3

Posted on Apr 8, 2013 5:04 AM

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Posted on Apr 8, 2013 5:18 AM

Your iPhone 4S takes photos that are 3264 x 2448 pixels. This is not negotiable. The 300dpi you want is a function of whether you are going to crop the picture, and whatever output device you are using.


Have a browse amongst this lot:


Pixels versus dpi

8 replies

Apr 8, 2013 8:22 AM in response to tonefox

Thanks Tonefox!


After looking at a few of the links I found a mathematical equation that assisted me.


Inches = Pixels/DPI

eg: 3 inches = 300 pixels/100 DPI


Using this equation and the fact that iPhone 4s takes photos that are 3264 x 2448 I was able to work out the largest print I could make with 300 DPI.


Width 3264 pix/ 300 DPI = 10.88 inches

Height 2448 pix/ 300 DPI = 8.16 inches


Therefore, the largest print (with 300DPI) I can make of these photos is 10.88 inches x 8.16 inches.


Which is great!


So is it critical for me to change the dpi in say photoshop or does it not matter as long as I don't go above the 10.88 inches x 8.16 inches?


From what I can gather the smaller I resize the photo the higher the DPI and the bigger I stretch the photo the lower the DPI?


Further clarification will be much appreciated. Thanks

Apr 8, 2013 8:48 AM in response to Munzie Magic

So is it critical for me to change the dpi in say photoshop or does it not matter as long as I don't go above the 10.88 inches x 8.16 inches?


From what I can gather the smaller I resize the photo the higher the DPI and the bigger I stretch the photo the lower the DPI?

You got it.


Photoshop gives you total control, as you might expect from a piece of software that costs about a week's income. If you define the required image size, the dpi will be adjusted to suit. If you define a required dpi, the image will be resized to suit. If you define an image size and a dpi, then Photoshop will resample the image to give you both.

Apr 8, 2013 9:08 AM in response to tonefox

Thanks again Tonefox! You have been a huge help!


I just want to confirm that it doesn't matter where you resize the photo that the same principals apply.

For instance if I resize a photo in word or in a photobook software, simply by zooming in or stretching/shrinking the image the dpi always changes when the size (inches) change. It's the number of total pixels that always stay the same?


Can I resize a photo in any software (even without measurements, just using the drag to resize feature) and know that as long as I keep in under those specific 10.88 inches x 8.16 inches it will always be above 300dpi?


Eagerly awaiting your response.

Apr 8, 2013 9:20 AM in response to Munzie Magic

For instance if I resize a photo in word or in a photobook software, simply by zooming in or stretching/shrinking the image the dpi always changes when the size (inches) change. It's the number of total pixels that always stay the same?

Unless you crop the photo, the pixel size is indeed constant. You have to hang on to the idea that"dpi" is only a relevant figure when outputting or viewing the image in some way. It is easy enough to zoom into an image in Photoshop to the degree that each pixel is a few millimetres square on your screen, and the dpi of your view is maybe only 10dpi or so. But you have done nothing to the image, you are only taking a different view of it.


Pixel is a measurement relevant to the image. Dpi is only a measurement relevant to the output medium of the image.

Apr 8, 2013 9:11 PM in response to tonefox

So irrelivant of how I change the size of the photo as long as I keep a 3264 x 2448 smaller than 10.88 x 8.16 inches it will still be 300 dpi?


Eg. Currently when I open a photo it opens at 72 dpi and a size of 45.33 x 34 inches but even if I drag and drop the corner of the image to resize the photo to 10.88 x 8.16 inches the dpi still changes to 300dpi. Is this correct?


I'm making a photo book that is 8 inches by 8 inches, the printer is telling me they require 300dpi.


So it doesn't matter how I get it to 10.88 x 8.16 inches (excluding croping) it will be 300dpi.

OR

Do I need to resize each photo in photoship before importing them?

Apr 9, 2013 1:33 AM in response to Munzie Magic

Everything you are saying is fine, including your maths.


I am probably being pedantic, and a lot of software will describe your resized image as "300dpi", whereas I am pedantically saying if you are looking at that image on a monitor which displays 72dpi, then what you are lookijng at is 72dpi. If you had a monitor with a 300dpi resolution, you would be looking at 300dpi. If you send that image to a printer which prints 300dpi, the printout will have 300dpi on it. The number of pixels in the photo (file) is not affected by any of this.


To be honest, I would expect a printer to receive your photo files straight from the camera, and do whatever is necessary to give you what you want.


By the way, if you do resize images by dragging a corner, for goodness sake do whatever you need to do to make sure you preserve the aspect ratio. There is nothing worse than images which have been squished either horizontally or vertically. Most software achieves the preservation if you hold down the shift key whilst dragging. It is far easier if you use software within which you can simpply define what you want numerically.

How do I take 300 dpi photos with my iPhone 4s? And how do I export them to my MacBook Pro at 300 dpi to use as I want to print photos.

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