Image Resolution versus Image File Size

[ScrappyPam]

Or: How do I get my picture to upload at the right size????

(The Simplified Version.)

In regards to your images, it's important to understand that the size you see on your monitor and the actual print size may be two different things. Why is that? Well, scanned and digital images are made up of two main components: Resolution and File Size. (There are really lots of others, but it can get pretty technical and we'll concentrate on these two for our purposes.)

Digital images are made of tiny dots called pixels (picture elements). Resolution is the image quality measured in terms of how many pixels make up your image. It is commonly referred to as "ppi" (pixels per inch) or "dpi" (dots per inch). (Note: ppi and dpi are often used interchangeably, but they really aren't interchangeable. PPI is the term for images, while DPI is a term for printers and they may be different numbers for the same image.)

On paper, 300 DPI is adequate for printing the average snapshot. Photography prepared for glossy magazines requires 600 DPI and higher.

An image seen on your PC monitor, however, will only display about 72 to 96 PPI - REGARDLESS of what the PPI of your uploaded image is. Because your images are to be viewed on a screen, all uploaded pictures/images should be no larger than 72 - 100 ppi. Anything higher has no improved effect, and only creates longer download times.


That's the basic explanation. Here's how it works:

It's easy to confuse photo size with file size. You can shrink the size of your picture, but that may not shrink the file size significantly. The file size is the number of kb in the photo. To decrease the file size you need to lower the resolution (dpi/ppi) of the photo.

Now, whatever program you use to view and save pictures on your computer should give you an option to save the file in lower quality, smaller file size or lower resolution (dpi/ppi). Whatever your program calls it, one of these options is what you will use to get that file down to 200kb or less.

You can reduce it to a very small file and it will still look fine on the message board. But it won't print well so you should save a new copy for uploading and keep your original in case you ever need the higher resolution again (for printing). Smaller photo files mean we can post more photos on message boards and galleries without creating problems or crashing the server.

Here's an example.

In the next post, the first (original) photo has the following attributes:

Pixel dimensions: 589 pixels X 598 pixels
Image size: 4.09 inches X 4.153 inches
Resolution: 144 ppi
File size: 88.4 KB

NOTE: 100 KB is the limit on file size for this message board. Because of the way uploading works, you will need to have a slightly SMALLER file size - so it needs to be UNDER 100 KB in order to upload.

In the third post, the second photo I resized for viewing on the web and now has these attributes:

Pixel dimensions: 294 pixels X 299 pixels
Image size: 4.083 inches X 4.153 inches
Resolution: 72 ppi
File size: 27.1 KB

What did I do? I adjusted the PPI from 144 to 72 and resampled the image. (Resampling refers to changing the pixel dimensions - and therefore display size - of an image. When you decrease the number of pixels, information is deleted from the image. It's ok to do this for web quality, but you wouldn't want to do this for print quality images.) That's it.

How this works for you will depend on the program that you use. Refer to the HELP files that come with your particular program for how to do this with your images.

Hope this helps!
Pam

[ScrappyPam]

Here's the original photo.

Pixel dimensions: 589 pixels X 598 pixels
Image size: 4.09 inches X 4.153 inches
Resolution: 144 ppi
File size: 88.4 KB

[ScrappyPam]

Here's the second - resized - photo.

Pixel dimensions: 294 pixels X 299 pixels
Image size: 4.083 inches X 4.153 inches
Resolution: 72 ppi
File size: 27.1 KB

[thecountryrose]

There's a very easy software you can download and try for free. It does all the work for you and what I use when my pic file is too big. Just two clicks and your picture is ready to post.

Easy Image:
http://www.easyimagesoftware.com/EasyImageLite.aspx

I use Easy Image Batch so I can do more than one photo at a time, but if you are just occasionally needing to resize, Easy Image Lite would be perfect.

[oniska]

Thank you thank you thank you I will give this a try