Wednesday, April 8, 2009

Image resizing

My research into digital image resizing for the web led me to a great site, Bob Atkins Photography. Finally I found something about this topic that is easy to understand and my questions were answered.

Self taught artist gave great advice when she said to change the pixel height and width. When you display a digital image on a monitor using a web browser the only thing that determines the size of the image when you enlarge it for viewing is the width and height of the pixels. I was surprised to discover that all other data in the image file is ignored, even resolution (ppi data). By fiddling with Adobe Photo Shop, I discovered that changing the height and width in pixels also produces a smaller file size (kb). That makes sense. The aim is to size the image so that when you click on it to enlarge it, it fills the computer screen without "going over" and to have it load quickly. Resampling your image to 640 by 480 pixels works well with most monitor sizes.

It seems I was mistaken when I thought that resizing would affect the amount of detail visible in my image on the web. The smaller the file size the less detail available when you print the image. The proof is in the pudding:

600 pixels wide

2232 pixels wide

What did I learn by comparing these two images?
  • no difference in the amount of detail visible
  • both are the same physical size in the post
  • can't tell how large they will be when enlarged until I publish the post
In addition
  • decreasing pixel height and width affect the size of the image when you enlarge it
  • decreasing pixel height and width affects how quickly an image loads

2 comments:

self taught artist said...

cool beans, i can't believe i gave helpful info! i never know what the heck i'm going half the time with this stuff.
will check that site out too!

Leslie Avon Miller said...

Thank you, thank you, and thank you. I have taken Photoshop classes twice, and picked up some stuff, but I know I need to know a lot more. The general adult Photoshop classes pertain to things like family photo restoration. I need specific skills for artists. I am thinking that every art workshop ought to have at least 15 minutes on using digital photography. I better stop now, because I could write a whole book on how frustrating it is to lack the skills one needs. Someone commented at my blog about the color purple in my painting; no purple. It is black....I have to wonder how distorted people's monitors make art work look as well.