How do I size a photograph for a
web page? How do I set the size of a photograph from my digital camera for a certain size to print? I hope to help you
answer those questions at the presentation on the April 28th meeting.
To help you prepare for the presentation
here are a few tips.
For digital photos the size is determined
by the size on the camera when it takes the photo. This size is stated in numbers of pixels across and down. The pixels in
a digital photo are like the grain or colored dots that make up the image of a film photo.
In a film photo the size is stated in a
dimension, inches or millimeters. In a digital photo the pixel is used because the pixel size is different from camera to
camera. The normal limitation on how big a print that can be made is determined when the grain or pixels become so noticeable
they are objectionable. This limit changes with the viewing distance. A photo on a billboard may have large grain or pixels
but because of the viewing distance they are not objectionable.
When you post a photo on a website or email
it size does matter. Most of the time when a photo is viewed on a computer there are 72 pixels per inch, or about 3 pixels
per millimeter. If you send an email with a lot of full size images from your digital camera you will notice it takes a long
time to send the email and sometimes the attachment will be so big the company you have your email account with will not send
it. By changing the size of your photos before you send them you can avoid this limitation.
What size are my images? First look at
the manual that came with your camera. You may find you can save the images in several different sizes. What is best? Because
we in the camera club normally want the best possible image to show at the meetings or hang on the walls of our house
we might save the highest quality our camera produces. Some times you may have a situation where this does not fit what you
want. For the maximum number of photos on the storage device in your camera you will have to decide how small can you stand.
Do this ahead of time and take photos of different size and compression and then look at the results on the medium you want
them displayed on. If you choose a small size and or a high compression method that choice is fixed. Another factor is how
fast your camera can take one photo after another. In most cases smaller sizes and compressed files result in faster action
from your camera. Your camera manual will give you this information.
You can see the size of each image by looking
at the file information displayed on file "details" when viewing the files on your computer. On windows computers there are
several options for viewing each file name, "details" is one of those choices. You can also "right click" on the file
name and see more information.
What size is right for computer viewing?
Like all other answers the answer is it depends on what you want. At one time a common computer screen size was 640 wide by
480 high in pixels. If you put a photo on that screen it would be that size or smaller. Now screens are bigger. Still a 640
by 480 makes a nice viewing size. Several will fit on a single screen and they show enough detail to get the idea across.
When sending a photo to a friend by email this size works fine unless you have some other need. If you want prints made from
a digital image file printers need 300 pixels per inch or more. That means if you want to send someone a photo to be printed
4 inches by 6 inches the file size would need to be 4 inches times 300pixels and 6 inches times 300 pixels. This would
be a 2,160,000 pixel file. Each pixel might need 8 bits. This would be a 17,280,000 bit uncompressed file. Because of the
use of compressed image files we do not have to send a file that large. You as a photographer do not have to worry about
all of this. The software will handle most of the math and other work. What do you have to worry about? When you open an image
in your photo editing software, some came with your camera, the first thing you do is "save as" another name. I just add an
"a" or a "1" after the camera's file name. There are several reasons for this. The first any changes you make will overwrite
"destroy" your original image. If the original image is compressed, called a .jpg, then every time you open and close that
image in your editing software the image is re compressed and the quality is degraded. Another reason is you may have several
uses for that image. You may want to print a large photo to mount on the wall. You may want to send a small version to someone
by email, and you may want to have one sized for a screen saver on your computer. Each would require a different sized image
file.
Come to the meeting and we can learn and
discus this subject to become better photographers.
Don't forget that the next meeting
will be at the Corpus Christi Museum down under the harbor bridge. Hope to see you there at 6:30 p.m. on April 28th.
