How do you change the resolution of a Photo?

Question

Level 1

4 points

How do you change the resolution of a Photo?

In iPhoto, how to you reduce the resolution of a photo in order to reduce the file size? This makes it easier to email because of the smaller file size?

21.5" iMac, Mac OS X (10.6.6)

Posted on Feb 1, 2011 6:21 PM

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Answer 1

LarryHN

Level 10

106,142 points

Feb 1, 2011 6:32 PM in response to iQMan

The basic answer - given that you give us no information about what you are doing - is to export the photos and select the size in the export

if you are using Apple mail it is as simple as selecting the size in the lower right hand corner of the message

Moe details would assist in giving a specific answer to your situation

LN

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Answer 2

iQMan Author

Level 1

4 points

Feb 4, 2011 12:09 PM in response to LarryHN

My Bad. My wife is editing the photos to use in a "Make your own book software". The software recommends a certain size or resolution to work with, which is usually smaller than the photos taken by digital cameras. When we had the PC, she would use the picture editor or Photo Shop to reduce the resolution or size of the pictures. We don't know how to do that on the iMac.

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Answer 3

LarryHN

Level 10

106,142 points

Feb 4, 2011 12:33 PM in response to iQMan

Again

export the photos and select the size (the largest pixel dimension) in the export dialogue

And again I now nothing except what you have told us but as a general rule for printing you would like at least 150 DPI and 300 DPI is better so normally using the highest resolution available will give the best prints - unless the photos in the book are very small you probably need the full camera resolution for 300 DPI - for example a full page 8 1/2 x 11" print needs a photo that is 2550 x 3300 pixels for a 300 DPI print

LN

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Answer 4

iQMan Author

Level 1

4 points

Feb 5, 2011 5:16 AM in response to LarryHN

Ok. Let's try this again. Let's say I have a photo with a resolution of of 3264 x 2448 pixels. How do I do the following:
1) I want to edit it and reduce the resolution to 1024 x 768 pixels.
2) Do this within iPhoto without using the export feature thereby keeping the edited photo in iPhoto?
On my PC I use MS Office Picture Manager to open a photo. It shows the current resolution size and the edited resolution size. It allows you to edit by custom width x height. It also allows you to compress file size while showing you original file size vs edited file size (e.g. 1.98MB vs 254KB).

The export feature in iPhoto does the following:
1) Places the edited photo outside of iPhoto. Don't want to do this as I want to keep it in iPhoto.
2) Allows you to choose jpeg quality or but doesn't tell you what the edited resolution or file size will be.
3) Allows you to choose jpeg size by custom but doesn't tell you what the edited resolution or file size will be.

If this is a limitation of iPhoto then I'm ok with that. I just wanted to know if there was another option.

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Answer 5

Yer_Man

Level 10

165,984 points

Feb 5, 2011 5:52 AM in response to iQMan

Let's say I have a photo with a resolution of of 3264 x 2448 pixels.

Tat's not a measurement of resolution, that's the dimensions (length x breadth) of the photo, expressed in pixels.

Resolution is a vague term most used to describe the density of pixels - i.e the pixels per inch.

1) I want to edit it and reduce the resolution to 1024 x 768 pixels.

No, you want to reduce the dimensions of the image to 1024 x 768

2) Do this within iPhoto without using the export feature thereby keeping the edited photo in iPhoto?

You can't. It can only be done on export. Why? When you edit a photo iPhoto preserves the original and makes a copy of the file containing the edit. As most people reduce the dimensions, file size or resolution for a specific purpose (to upload it for instance), it's thought best to export it, upload it nd then trash it.

Of course, you can simply import the export back in, if you have a burning need of it in iPhoto.

Regards

TD

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Answer 6

LarryHN

Level 10

106,142 points

Feb 5, 2011 8:24 AM in response to iQMan

3) Allows you to choose jpeg size by custom but doesn't tell you what the edited resolution or file size will be.

That is what you ask to do - change the maximum pixel dimension to 1024

If you want to change the photo ratio then crop it prior to export - in your case crop to 1024x768 and ten export with a maximum dimension of 1024

LN

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