The Resizer is used to change the dimensions of an image.  In digital photography size can mean at least three different things: dimension in pixels, dimension in inches when printed, file size (read more about these different concepts of "size" here).  Resizer is used primarily for the first two.  It is used to set the actual number of pixels in the image or adjust the size that an image will print.  The Resizer is used to create smaller images that use less disk space.  The Saver is used to adjust the compression settings (and thus file size) of an image without adjusting its pixel dimensions.  Resizer is a very useful feature for creating thumbnails or smaller images for web pages where download speed is important, or for creating smaller images to send in email.  Resizer uses high-quality bicubic interpolation to produce the highest quality results.

There are two ways to make an image's file size smaller.  One is to reduce the number of pixels in the image (change the resolution).  The other is to compress it more (change the quality).  The Resizer reduces the number of pixels in the image.  To save the file with more compression, use the Saver.  Together these two utilities give control over the file size for the image you will create.

The Resizer allows you to set the size in pixels of the image it will create.  For example, a Nikon Coolpix 990 when taking pictures at its highest resolution generates images that are 2048 x 1536 pixels which is a total of 3,145,728 pixels.  If you have Resizer set to generate a 640  x 480 picture you will create a smaller version of the picture that only uses 307,200 pixels.  That is less than 10% as many pixels as the original.  Of course, this means that the file needed to save the image should also be much smaller.  The Resizer goes to great lengths to create a highest quality image at the desired resolution.

Common Operations

In the case where you want to maintain the original image aspect ratio and just make the image smaller, use either Match Long Side or Match Short Side.  This is a common operation for sending reduced size images in email or saving images to a website.

If you are creating a web page and would like to create thumbnails that are all be of uniform width so that the columns of a table will be properly lined up, try Match Width, Match Height Letterbox (landscape or portrait) or Crop (landscape or portrait).

Aspect Ratio

The aspect ratio of a picture is the number of horizontal pixels divided by the number of vertical pixels.  As it happens, in the example above, both the Nikon 990 high-resolution image format and 640 x 480 have an aspect ratio of 4 x 3.  Resizing between those two sizes is straight forward.  The number of pixels in each dimension is reduced to the desired amount.  However, some cameras, and pictures have different aspect ratios.  For example the Canon D-30 high-resolution JPEG format is 2160 x 1440 pixels.  If you compare this to the Nikon you will see that the D-30 image is wider and shorter.  Its aspect ratio works out to be 3 x 2.  If you try to resize it to be 640 x 480 pixels (an aspect ratio of 4 x 3), what should it do?  digital photo utilities gives you several options.

Note: Most of the options under Aspect Ratio Adjustments will only apply to situations where the source and destination images have different aspect ratios.  If the source aspect ratio matches the desired aspect ratio, many of the options will produce the same result. Match Height and Match Width are exceptions.  When these options are selected only one parameter (height or width respectively) is available so the source aspect ratio is always maintained.

If the "Don't Resize Small Images" button is checked, images that are already smaller than the desired size will not be affected by the Task.  If it is unchecked, smaller images may be made larger to match the desired dimensions.

Click for more details and examples of the Resizer settings.

Resizing for Printing

Resizer allows you to set the size that an image will print.  If you set the Print Size, the image will be printed by a printer at the specified size (in inches).  Notice that it does NOT crop the image, so if you set a normal digital camera image to print at 1 x 8 inches the result will be a very long skinny image.  To crop the image at the same time, set the Aspect Ratio Adjustments to "Aspect Ratio Only," and set the aspect ratio to match the print size.

If you would like to optimize the printer output quality, you may specify a DPI setting to match your printer.  The printed image size will be determined by the number of pixels in the image.

Batch Settings

Use these settings to determine how the Resizer will interact with you as it carries out an action.

Don't Query - use the settings that have been entered for all images

Query Once - for each time this action is invoked (whether for one image or 100 images) allow the user to set the parameters

Query Per Image - for each image, display a dialog box to allow the user to adjust the settings for that particular image