Changing dpi of photos in iPhoto

[jgreenfield]

I need to send photos of paintings to a curator and she needs 300 dpi. I have no idea how to do that. Usin iPhoto.
Can anyone help?

 

[RadDave]

Hello - now, I don't use iPhoto that much and although there are some basic photo cropping and editing features, not sure if image resizing is an easy option.

However, images can be easily resized in Preview - take a look at the second post in THIS THREAD - in the second image posted 'pixels/inch' (ppi) can be changed to 'dots/inch' which is DPI - the resolution in that pic is 72 ppi which can be increased to 300 (or whatever number).

NOW, you need to understand that 300 dpi is the standard resolution needed for a decent print, and that the size of that print for good quality is dependent on the MP (megapixel) size of the original image; if your curator is planning to 'publish' your images then you'll need to know their maximum dimensions and provide ones w/ enough MPs to match the desired size of the printings - see the attached chart below.

SO, just as an example, an 8" x10" print for excellent printed quality would require a 6 MP image - hope this helps and let us know if the directions are clear. Dave

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[jgreenfield]

Changing DPI

Hi Dave,
Thank you very much. Extremely helpful for now and the future.
Joyce (jgree field)

 

[BMan1245]

Where do I preview and be able to change the PPI? Can not seem to find that in iPhoto.

 

[RadDave]

Where do I preview and be able to change the PPI? Can not seem to find that in iPhoto.

Hello and welcome to the forum!

First, assume that you are using a Mac w/ OS X? If so, Preview is the built-in image (and PDF) viewer w/ editing features - just click on an image on your computer and it should open in the app (i.e. if the default has not been changed and depending on the image format).

Second, please follow the link in my previous post which discusses how to re-size an image; also, there are several subsequent posts that discuss re-sizing in iPhoto. Let us know if this helps. Dave

 

[BMan1245]

Thank you!

 

[BMan1245]

Getting an error message in Preview

I am trying to use Preview to resize a photo to 300 DPI. I am getting an error "This document is on a volume that does not support permanent version storage." Not sure what my next step should be.

 

[RadDave]

I am trying to use Preview to resize a photo to 300 DPI. I am getting an error "This document is on a volume that does not support permanent version storage." Not sure what my next step should be.

Hello again - please provided some information: 1) What Mac computer (model/year) are you using; 2) What OS X is installed; 3) Where is the 'document' located (e.g. your HD or an external device, and if the latter, what kind?); 4) What format is the photo in question is, i.e. JPEG or other; and 5) Did you google the above statement? If not the latter, then check this Apple Support Article - Dave

 

[BMan1245]

iMac (Late 2009), OS X Yosemite ver 10.10.2, I have them on both my hard drive and an 8GB thumb drive. The photos are in JPEG. Yes, I went to the Apple support, but it basically repeats the error message. Maybe I should purchase Photoshop and hope it can covert the photos. The photos I have converted to grayscale for a history booklet. Most I scanned into the iMac not realizing that I could specify 300 DPI when I was scanning them in months ago.

 

[RadDave]

iMac (Late 2009), OS X Yosemite ver 10.10.2, I have them on both my hard drive and an 8GB thumb drive. The photos are in JPEG. Yes, I went to the Apple support, but it basically repeats the error message. Maybe I should purchase Photoshop and hope it can covert the photos. The photos I have converted to grayscale for a history booklet. Most I scanned into the iMac not realizing that I could specify 300 DPI when I was scanning them in months ago.

Thanks for the information above - since these files are on your HD & a thumb drive (assume same issue regardless of trying to view them from either source?) and in JPEG format, Preview should be able to open them easily - not sure if Photoshop will correct the issue (if there is a 'free trial' download then nothing to lose).

You might want to try Adapter, a free app that can convert all sorts of audio, video, & image files - see if the JPEGs can be changed to another format, such as PNG and then be read by Preview - costs nothing and the app is easy to use.

Finally, you mention that you originally wanted images at 300 DPI which is the standard for a printed version, but keep in mind that if you scanned your images at a much lower resolution, such as 72 PPI, taking the latter to the much higher resolution is not going to provide you a satisfactory image for printing. Dave

 

[doobido]

Re changing dpi of photos in iPhoto

Am I missing something here? I use Preview all the time and there is nowhere that I can find to change the ppi to dpi. On my version, I only have the options of pixels/in or pixels/cm. I also have to change the resolution of images for a createspace book and they will not accept anything under 300 dpi but saving the book in word automatically saves at 72 ppi when shown in preview. PPI and DPI are not the same. Is there someplace that is easy to do this. I have specific sizes for my images and I need the resolution to be 300 dpi.

Hello - now, I don't use iPhoto that much and although there are some basic photo cropping and editing features, not sure if image resizing is an easy option.

However, images can be easily resized in Preview - take a look at the second post in THIS THREAD - in the second image posted 'pixels/inch' (ppi) can be changed to 'dots/inch' which is DPI - the resolution in that pic is 72 ppi which can be increased to 300 (or whatever number).

NOW, you need to understand that 300 dpi is the standard resolution needed for a decent print, and that the size of that print for good quality is dependent on the MP (megapixel) size of the original image; if your curator is planning to 'publish' your images then you'll need to know their maximum dimensions and provide ones w/ enough MPs to match the desired size of the printings - see the attached chart below.

SO, just as an example, an 8" x10" print for excellent printed quality would require a 6 MP image - hope this helps and let us know if the directions are clear. Dave

.

 

[RadDave]

Am I missing something here? I use Preview all the time and there is nowhere that I can find to change the ppi to dpi. On my version, I only have the options of pixels/in or pixels/cm. I also have to change the resolution of images for a createspace book and they will not accept anything under 300 dpi but saving the book in word automatically saves at 72 ppi when shown in preview. PPI and DPI are not the same. Is there someplace that is easy to do this. I have specific sizes for my images and I need the resolution to be 300 dpi.

Hello and welcome to the forum! First, Preview does not have a dpi option because digital resolution on a computer monitor deals w/ pixels (and of course RGB colors, kind of like sub-pixels) and 72 ppi is a standard monitor resolution for displaying images (of course this has changed w/ HD monitors/HDTVs depending on their dimensions). So, you will have to deal w/ pixels when using photo imaging software on a computer - please review PPI vs. DPI: what’s the difference? for a more thorough discussion.

Dpi is 'dots per inch' and refers to the density of dots (usually CMYK subtractive colors - kind of 4 sub-dots) on a printed media, such as a photograph. For a good quality 'printed picture', 300 dpi is the usually standard - so a 'pixel' on a monitor is of defined size and consists of using 3 projected colors, i.e. RGB, whereas a 'dot' is a color on a printed page that can vary in size and uses CMYK inks, as in an ink jet printer.

But the bottom line is that 'ppi & dpi' are pretty much transferable from a computer image to a printed one, i.e. you need preferably an image that is 300 ppi AND enough total pixels to provide the size printed picture desired, as shown in the chart that I posted previously. Hope this helps. Dave