All About Digital Photos
 
Changing the Size of Digital Photos

At some point or other you're likely going to want to change the size of a digital photo. This will usually be to serve an intended purpose such as emailing a smaller sized version of your original photo. In most instances you will be reducing the size of the image. Several topics are discussed on this page including enlarging photos, reducing digital photos, the aspect ratio of digital photos, cropping digital photos and emailing digital photos.

Original Photos
Your original digital photos, whether they be from your digital camera or from a scanner are your "negatives" and should never be touched. Keep them in a safe place and always work on copies of your originals. See the Storage Page for details about how to properly save and archive your originals.

Enlarging Digital Photos
Digital photos do not take well to being overly enlarged and this is generally to be avoided. If you want to print an image it is usually best to first try printing using the original size and quality of your digital photo. Your printer software will make the adjustments.

If you really want to digitally enlarge a digital image then the best bet is to either use proven workflow routines to optimize enlarging or get software specifically designed for this purpose (i.e. Genuine Fractals or SI Pro). If you are using a program such as Adobe Photoshop, the "quick & dirty" way to do a reasonable digital enlargement results is by doing the enlargement in increments of 10%. Keep doing 10% enlargements until the distortion that results becomes too great for you and then step back one step and save the resulting enlarged image. There are much better, but more complicated Photoshop techniques. An excellent one can be found on Digital Outback. For others, do an Internet search for "Upsizing Digital Images" and "Enlarging Digital Images."

Reducing Digital Photos
The most common size adjustment for a digital photo is to reduce its size, either for a specific purpose (i.e. emailing, posting to a website) or to crop the photo. Specifics regarding cropping and size reduction for emailing are in the two sections following this one.

One note is that after a digital photo has been resized, it will need to be re-sharpened. Sharpening comes in many flavours and sometimes it can be a bit hard to find in a program. For instance, in Adobe PhotoShop (CS or Elements), the most effective sharpening tool is the "Unsharp Mask" that you will find under the "Filter" menu using the "Sharpen" option. In IrfanView it is under the "Image" menu but for greatest control you'll have to open the "Effect" option and choose "Effects Browser" in order to visually control the amount of sharpening. In Breezebrowser it is part of the "Proofs" dialog box and uses settings similar to Adobe PhotoShop's "unsharp mask". There is a whole science to doing high quality sharpening, do an Internet search for "Sharpening Digital Images."

Aspect Ratio of a Photo
The aspect ratio of a photo is the ratio of the width of a photo compared to the height of the photo. For instance, a square photo would have a 1:1 aspect ratio (width is the same as the height). Conventional 35mm film has a 1.5:1 aspect ratio (or 3:2 as expressed in whole number terms). Many "point & shoot" digital cameras produce photos with a 1.33:1 (4:3) aspect ratio while most digital SLR cameras generally use the 35mm 1.5:1 aspect ratio. Some cameras allow you to choose the aspect ratio of the photos it takes. You can determine the aspect ratio of your digital images by looking at the pixel dimensions. A photo with dimensions of 2048 x 1536 pixels would have an aspect ratio of 1.33:1 (length divided by width). A photo with dimensions of 3504 x 2336 pixels has an aspect ration of 1.5:1.

The problem people run into is with printing since the aspect ratio of the printing paper doesn't always match the aspect ratio of the photo. Common photo paper sizes in North America include 6" x 4" (1.5:1 aspect ratio), 7" x 5" (1.4:1), 10" x 8" (1.25:1) and 11" x 8.5" (1.29:1). You'll note that all these paper sizes have different aspect ratios and only one matches a common digital photo size aspect ratio. To print your photos to a paper size that has a different aspect ratio, you'll either end up bordering the photo to match the aspect ratio of the paper, or cropping the photo.

original photo with 1.5:1 aspect ratio
printed to 8.5 printed to 8.5
Printing to different aspect ratios

The top photo is a 1.5:1 aspect ratio photo from the camera. The bottom two photos show the choices that can be made when printing to 8.5" x 11" paper, which has a 1.29:1 aspect ratio. The lower left photo has whitespace added to change the aspect ratio from 1.5:1 to 1.29:1. This allows the photo to be printed full frame with no cropping. The second photo has been cropped to a 1.29:1 ratio, the same ratio as the paper, so that it can completely fill the paper. With cropping, some of the photo had to be removed to make it fit full size on the paper.

If you simply give your photo to a commercial printer, it will most likely either be automatically bordered or automatically cropped (some printers do offer a manual cropping service). Problems can crop up (so to speak) with automatic cropping. If you have people objects going from edge to edge, they can get chopped off during cropping. A beautifully composed shot can be ruined by bad cropping. So, it is best if you can do your own cropping to send an image that will exactly match the aspect ratio of the paper you intend to have it printed on.

You may also want to do cropping for a slide show destined to be shown on a TV or computer monitor. Older TVs generally have an aspect ratio of 1.33:1 (4:3) while today's HD TVs and monitors have an aspect ratio of 1.78:1 (16:9) to match HD TVs and monitors. If you know what kind of TV/monitor the slide show is to be played on (i.e. HD) then you can crop the images to match that ratio, allowing them to be shown full screen, with no borders.

Cropping Digital Photos
A common size change for a digital photo is cropping. This can be done to either simply change the aspect ratio of a photo (as discussed above), recompose the photo (change the apparent balance of objects in the photo) or "zoom in" on a section of the photo (create a new photo of just a portion of the original photo). The latter two objectives of cropping are often one and the same.

   Pre-cropped
Cropped
Top: original photo with a 1.33:1 aspect ratio. Cropping marquee is shown
Bottom: Cropped to a 1.5:1 aspect ratio
Cropping involves selecting a portion of the image and removing the rest. This creates a new smaller image with just the portion of the image that you want. Cropping can be used to remove annoyances in the photo, to "zoom-in" on a selected portion of the photo, or to change the aspect ratio of the photo so that it can be printed full frame on a selected paper size (or viewed with no bordering on a monitor/TV).

In the example on the right, the photo is being cropped both to enlarge a portion of the image and also recompose the image (cropping to remove a couple of unwanted elements and changing the "balance" of the photo). It is also being cropped to a different aspect ratio (changing from a 1.33:1 (4:3) ratio to a 1.5:1 (3:2) ratio.

Most good photo programs have a cropping tool. In Photoshop Elements for instance you would use the "Rectangular Marquee Tool" to select an area of the photo. Note that this tool can be set to be a fixed aspect ratio (i.e. 3:2). A quick shortcut if cropping to a certain paper size aspect ratio is to simply enter the paper size as the aspect ratio (i.e. 8.5:11).

Once you've selected exactly what you want, you would use the "Image > Crop" function to produce an image with only the selected portion of the photo with the aspect ratio of the paper you intent to print the photo onto.

Many photo printers come with software that allow the easy printing of photos and include a built in cropping tool (whose aspect ratio will match the paper size you have chosen), allowing you to crop the photo to the desired printing size.

Emailing Photos

One of my pet peeves is digital photo bloat and this is especially true when it comes to emailing photos. There is no point in sending "just to see" photos of a larger viewing size than a normal computer screen - it's just annoying. These images should be reduced in both pixel dimensions and computer file size. Some of you will have software that came with your camera that will automatically do this for you. Others will have to rely on separate photo software. My recommendation for emailing size is a photo with a horizontal dimension of about 800 pixels and a JPEG quality of between 50 and 75. My favourite program to change digital photos for emailing is Breezebrowser, but I'll outline procedure for Windows 7, Vista, Windows XP, Adobe Photoshop and Irfanview as well:

Windows 7, Vista, XP and 2000 - Best & Easiest Method

Download and install the freeware Resizer Powertoy Clone (available for either 32 bit or 64 bit computers) www.codeplex.com/PhotoToysClone.

Now, when you right mouse click on any photo, you'll see an option that says "Resize Pictures" - click on that and you'll get options for Small, Medium, Large, Mobile Phone or you can choose a custom size. When you select one, it will instantly re-size a copy of your image and save it back into the same folder, with the same filename except with the resize size in brackets (i.e. mypicture.jpg to mypicture(small).jpg). Your original photo is not affected, you now have a new smaller photo, perfect for emailing (or any other use)

Windows 7 and Windows Vista - Alternate Method

  1. Open up the photo you want to re-size using Windows Photo Gallery (the default photo viewer)
  2. With the photo selected, choose "E-mail" from the main menu
  3. Select the new image size (i.e. "Medium") and click the "Attach" button
  4. Your email program will open up with the new resized photo as an attachment
You don't have to email the photo if you simply want to save the re-sized photo on your computer. Just click on the photo attachment in the blank email and choose to "Save" it back to your computer.

WARNING: When saving the resized file it is best to re-name it (add "med" or "small" to the filename). NEVER overwrite your original photo with the resized photo.!!

Now just delete the email. Your new resized image will be where you saved it.

(note to Microsoft - in the next version of Windows, please build in something equivalent to the very easy to use Resizer Powertoy - update for Windows 7 - they didn't - maybe for Windows 8?).

Windows XP

  1. You will first have to download and install the freeware Resizer Powertoy Clone (which also supports 64 bit, Vista, and Windows 7) - www.codeplex.com/PhotoToysClone
  2. Open up a view of your images using Windows Explorer or My Computer
  3. Select the image(s) you wish to resize
  4. RIGHT mouse click on the selected images
  5. In the dialog box that pops up, choose "Resize Pictures"
  6. Choose the size you want and click OK
  7. Copies of your new resized images (with a size ( ) in the filename) will appear in the folder with your other images

Adobe Photoshop Method

    Adobe - image size dialog box - resample image
    note that both the "Resample Image" and the "Constrain Proportions" boxes are CHECKED and that the WIDTH box in the Pixel Dimensions section has been set to 800 (the program will automatically set the height).
  1. Load a copy of your photo into Adobe Photoshop (or Photoshop Elements).


  2. Select the "Image > Image Size" menu option (may be "Image > Resize > Image Size" in Photoshop Elements).


  3. In the image size dialog window, make sure that the "Resample Image" and the "Constrain Proportions" checkboxes are selected (checked).


  4. In "Pixel Dimensions" section type in 800 in the Width box (assuming that the image you are working with has a width greater than 800


  5. Click the "OK" button - Sharpen the image if required


  6. Your photo will be resampled using its original aspect ratio (which is what Adobe means by the obtuse "Constrain Proportions").


  7. Use "Save As" to save this photo in JPEG format with a new name - I suggest adding a -email extender (i.e. "345-2365-email.jpg"). Click "OK"


  8. The next dialog box are your JPEG options, choose Quality 5 or 6.


Current versions of Photoshop have a "Save to Web" which can do the above in a single process and make a smaller file to boot. If you have this option use it. It will allow you to change the image size and select your JPEG compression in one step. Note though that "Save to Web" will strip out any IPTC data you have in the image.

Irfanview Method

  1. Load a copy of your photo into Irfanview


  2. Select the "Image > Resize/Resample" option


  3. In that dialog window make sure that "Preserve Aspect Ratio" is selected


  4. In the "Set New Size" section, make sure that "pixels" are selected and input 800 for width


  5. Click on the "OK" button. Sharpen the image if required.


  6. Use "Save As" to save this photo in JPEG format with a new name - I suggest adding a -email extender (i.e. "345-2365-email.jpg"). In the flyout box select 50 as the quality



You can also change the size of multi photos using the Batch Conversion routine in Irfanview (also accessible from the thumbnail view).

Breezebrowser MethodBreezebrowser Resize (Proof) Window

  1. View your photo directory with Breezebrowser (thumbnail images)


  2. Select all the images you want to change


  3. Under the "Tools" menu select "Proofs"


  4. Make sure that "Resize" image is selected and set Max Size to Width of 800 and height of 600


  5. Set any image enhancement options you want (i.e. sharpening). You might also want to add a watermark (your name, EXIF photo date, IPTC caption, etc.)


  6. In output settings, choose JPEG with Quality 65. The default output directory is a subdirectory called "proofs" but you can change this to whatever you wish.


  7. In the Rename section if you enter "%o-email" it will add "-email" to the original filename of the image.


  8. Click on "Proof Selected" then use Breezebrowser to look at the results in your "Proofs" directory (or wherever you have put them).


In this particular example, the original image was 3504 x 2336 pixels in size with a filesize (as a JPEG) of 2.2 Mb. The resized 800 x 600 image is 54K (0.054 Mb) in filesize - nice and tiny for emailing yet still perfectly viewable on any computer monitor or TV.

More Options

Do an Internet search (i.e. Google) for "resizing photos for email software" and you'll get lots of hits, including dozens of free software packages designed to resize photos and even some services that will do the conversion on-line.


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