Don't Crop Too Much

When You Crop, You Chop Out Data

One of the easiest tools to use in a Photo editing program is the "Crop Tool".  Most all Photo programs, including the low end ones, have this tool.

But you need to be careful when using this tool because you can over-do-it.  When you crop a photo, you are eliminating data, or pixels from the photograph.  If you then insert the cropped photo into a document or try and print it as large as the original size, the resolution will be decreased and you will lose a lot of quality and clarity in the photo.

If you know the resolution you need to print the photo and you pay attention to how much you are cropping, you can avoid problems and having photos that look fuzzy when you print them.

Know The Resolution of Your Photo Before You Crop

There are several ways to find out the Resolution of your photos. 
Resolution tells you the number of pixels in the photograph.
A pixel is one dot of color in a digital photograph.

1. Check your digital camera and find it's megapixel rating and the resolution setting you used when you took the pictures. 
    
   • See Digital Photo Quality and Resolution to learn about megapixels and setting your digital camera to take high resolution photos,
      
2. Use a Photo editing program to check the resolution of a picture that you have on your computer.  Most photo programs will give you this information.  Check out the menu system of the program and look for something like "Picture Properties" or "Picture Information" or "Resolution" or "Picture Size".
    
3. Use a document window that displays information about files on your computer.
   If you are using the Windows XP Operating System:
   1. Click on the "Start" button
   2. Click on "My Documents"
   3. Locate the folder where you have your pictures
   4. Right click on the photo and this will bring up a menu with options
   5. Left click on the "Properties" option
   6. Click on the "Summary" tab at the top and this will display the vertical and horizontal resolutions.

A Cropping Example

For example, let's say you have a digital photo that is 1200 pixels vertical and 1600 pixels horizontal, as shown below.

If you decide that you only want to use the upper right corner of the picture, you would use a photo editing program and crop the photo to one-half the width and one-half the height as show in the illustration below.

The resulting image is 800 pixels horizontal and 600 pixels vertical.

• The photograph you started out with was a 1.92 megapixel image.
  1600 pixels x 1200 pixels = 1,920,000 pixels or 1.92 megapixels.

• The image you now have is 0.48 megapixels
  800 pixels x 600 pixels = 480,000 pixels or 0.48 megapixels.
  That's one fourth the size of the original.

This difference in pixel size can make a big difference if you are going to print the photo in a document or on photo paper and you want to keep the original size.

Know The Resolution of Your Photograph When You Print

Now let's say that you want to print your image out on a color printer at a standard looking photo size of 6" by 4½".
With the original image, before you did the crop, the number of pixels in the original photograph would have given you a print quality of  267 dpi (dots per inch).  This is a pretty good print quality.

• 1600 pixels in the photo length divided by 6 inches of printing length = 267 dpi print quality

dpi stands for Dots Per Inch.  This is how many dots of ink your printer will squeeze into one inch on your paper.  The more dots you have per inch, the better will be the quality of the printed image.

Now if you take the cropped image and stretch it out to fit into the same size rectangle of 6" by 4½", you will get a print quality of 133 dpi, which is not very good.

• 800 pixels in the photo length divided by 6 inches of printing length = 133 dpi print quality

So, when the original photo was cropped to one fourth of it's size, you lost three fourths of the pixels.  Then by printing the cropped image at too large of a size, you ended up with a LOW Print Quality of 133 dpi.

You will have to be the judge as to whether the final print quality meets your expectations, but if you are going to print a photo on a color printer you should try to have a print quality of a minimum of 200 dpi, especially if you are going to reproduce it after printing.
 

As a general rule, when printing photographs on a color printer, use the following guideline:

1. 300 dpi = Good Quality
2. 200 dpi = OK Quality
3. 100 dpi = Low Quality

• See Digital Photo Quality and Resolution to learn about megapixels and setting your digital camera to take high resolution photos,
   
• See Printing Digital Photos and dpi for information on getting good prints from your photos.