Compressing images: Difference between revisions

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This article suggests several ways to convert your image files to smaller sizes that are still good enough to use in presentations, etc.  
Keeping high resolution photos is fine if you have plenty of hard disk space, but if you are going to send a bunch of them by email, you will want to shrink them first.  Likewise, when you include them in a presentation, it will slow down your work and result in a huge file.  


Keeping high resolution photos is fine if you have plenty of hard disk space, but if you include lots of them in a presentation, it will slow down your work and result in a huge file.
In the past it was often necessary to use a specialist image manipulation program first, to save smaller copies, before working with them in your application program. Nowadays, however, various programs can shrink the files in more convenient ways.  


=Image and photo programs=
=Image and photo programs=
Specialist programs like Pixelmator or Graphic Converter are often included in special-offer software bundles.  These can do what is needed and a great deal more.  
Specialist programs like '''Graphic Converter''' or '''Pixelmator''' are often included in special-offer software bundles.  These can do what is needed and a great deal more.  


However, you can also simply open each image in Apple's wonderful Preview program, then choose File: Save As, and choose a smaller resolution/ file size.  
However, you can also simply open each image in Apple's wonderful '''Preview''' program, then choose File > Save As or File > Export, and choose a smaller resolution. In Preview it is also easy to cut out parts of the image ([[:File:Mail Rules Edit Header List.png|click here]] for an example), and to annotate the image e.g. with additional text.


iPhoto is another easy program that you could use.  A quick tip is to select multiple hi-res images in iPhoto, then Share: Email, and choose from the simple list of small, medium or large size. This creates an email with lower resolution images attached.  Don't send it, just drag the images out and into whatever other program needs them.   
=Emailing from iPhoto=
'''iPhoto''' is another easy program that you could use.  Select one or more hi-res images in iPhoto, then Share > Email, and choose from the simple list of small, medium or large size. This creates an email with lower resolution images attached.   


=Powerpoint=
A quick tip is to use the steps above even when you don't want to send the photos by email. You can then just drag the images out of the draft email into whatever other program needs them.   
In PowerPoint 2004 and 2008, there is an option in Preferences to compress graphic files[http://facultysupport.ucdavis.edu/techtips/pdf_dl/Compressing%20Images%20in%20PowerPoint%20for%20Mac.pdf This pdf] from UC Davis, California, explains where to find it.


In PowerPoint 2011, you can click on a graphic/picture, and one option in the toolbar will be "compress".
=Keynote=
In '''Keynote''', to reduce the file size of an individual image that you’ve masked or resized, select the image and choose Format > Image > Reduce Image File Size. (You must save the Keynote document first.)
 
To reduce the sizes of all masked and resized (shrunk) images, and shortened videos, choose File > Reduce File Size.
 
=PowerPoint=
In '''PowerPoint''' 2004 and 2008, there is an option in Preferences to compress graphic files.  [http://facultysupport.ucdavis.edu/techtips/pdf_dl/Compressing%20Images%20in%20PowerPoint%20for%20Mac.pdf This pdf] from UC Davis, California, explains where to find it. This affects all your photos in all your presentations.
 
PowerPoint 2011 is more flexible (like Keynote) as it helps you shrink individual images, or all images in a particular presentation. You can click on a graphic/picture, and one option in the toolbar will be "compress".
Alternatively, the File > Reduce File Size option will resize all photos within the presentation. It lets you choose the picture quality and you can crop the non-visible portions of any images.
 
=Automator=
Automator, which is included in OS X, can be used to rename and resize a batch of images.  [http://www.tuaw.com/2012/12/03/preparing-blog-images-with-automator/ This article] at The Unofficial Apple Weblog teaches you how to build a workflow for this.  


=Credits=
=Credits=
Contributed by several people in a discussion on the [[Mac Ministry List]] in February 2011.
Contributed by several people in discussions on the [[Mac Ministry List]] in February 2011 and December 2012.


[[Category:How-to guides]]
[[Category:How-to guides]]

Latest revision as of 23:12, 2 January 2013

Keeping high resolution photos is fine if you have plenty of hard disk space, but if you are going to send a bunch of them by email, you will want to shrink them first. Likewise, when you include them in a presentation, it will slow down your work and result in a huge file.

In the past it was often necessary to use a specialist image manipulation program first, to save smaller copies, before working with them in your application program. Nowadays, however, various programs can shrink the files in more convenient ways.

Image and photo programs

Specialist programs like Graphic Converter or Pixelmator are often included in special-offer software bundles. These can do what is needed and a great deal more.

However, you can also simply open each image in Apple's wonderful Preview program, then choose File > Save As or File > Export, and choose a smaller resolution. In Preview it is also easy to cut out parts of the image (click here for an example), and to annotate the image e.g. with additional text.

Emailing from iPhoto

iPhoto is another easy program that you could use. Select one or more hi-res images in iPhoto, then Share > Email, and choose from the simple list of small, medium or large size. This creates an email with lower resolution images attached.

A quick tip is to use the steps above even when you don't want to send the photos by email. You can then just drag the images out of the draft email into whatever other program needs them.

Keynote

In Keynote, to reduce the file size of an individual image that you’ve masked or resized, select the image and choose Format > Image > Reduce Image File Size. (You must save the Keynote document first.)

To reduce the sizes of all masked and resized (shrunk) images, and shortened videos, choose File > Reduce File Size.

PowerPoint

In PowerPoint 2004 and 2008, there is an option in Preferences to compress graphic files. This pdf from UC Davis, California, explains where to find it. This affects all your photos in all your presentations.

PowerPoint 2011 is more flexible (like Keynote) as it helps you shrink individual images, or all images in a particular presentation. You can click on a graphic/picture, and one option in the toolbar will be "compress". Alternatively, the File > Reduce File Size option will resize all photos within the presentation. It lets you choose the picture quality and you can crop the non-visible portions of any images.

Automator

Automator, which is included in OS X, can be used to rename and resize a batch of images. This article at The Unofficial Apple Weblog teaches you how to build a workflow for this.

Credits

Contributed by several people in discussions on the Mac Ministry List in February 2011 and December 2012.