Are you using something like Photoshop or Fireworks? In the Image Size box, there is a checkbox called "Resample Image". You probably have that (or something equivalent) checked and it's physically reducing the number of pixels in the image. That's why you're seeing that effect.
When you do that, you're not _really_ changing the dpi, you're changing the total number of pixels. You're actually creating a different image, not the same image at a different dpi resolution. The software just provides the ability to edit the dpi as a shortcut to calculating the resize ratio. If you uncheck that box and change from 300 to 72, you're now actually preserving the image AND changing the effective dpi. The only accurate measure of an image's true size is the number of pixels in the image. Resolution (dpi/ppi) is just a measure of how many of those pixels are in a given size. If you preserve the number of pixels, the resolution will increase as you shrink the display/print size because it's the same number of pixels in a tighter space. Inversly, the resolution will decrease as you expand the display/print size. Understanding this relationship is integral to manipulating graphics between screen and print, but a lot of people don't really get into it because the tools generally do a good job of hiding it. But the image manipulation tags are probably going to expose it, and it's the format you'll need to work with. -Kevin ----- Original Message ----- From: "Rick Faircloth" <[EMAIL PROTECTED]> To: "CF-Talk" <[EMAIL PROTECTED]> Sent: Thursday, September 11, 2003 9:42 AM Subject: RE: Image manipulation > Hi, Kevin...and thanks for the reply and help... > > I'm not quite sure how this works out: > > >A 800x600 image at 72 dpi is exactly the same > >as a 800x600 image at 300 dpi. > >They both weigh in at 1.4MB > > I took a 1051 x 2098 image and at 300 dpi it's 3,067KB. > At 72 dpi, it's 360 x 503 and 220KB... > > That's quite a difference when the file is uploaded and displayed > on screen. They both can be made to fit a 320 wide area onscreen, > but the 72 dpi resolution image is obviously more desirable because > of reduced file size that's loading onto the page. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| Archives: http://www.houseoffusion.com/lists.cfm?link=t:4 Subscription: http://www.houseoffusion.com/lists.cfm?link=s:4 Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=89.70.4 This list and all House of Fusion resources hosted by CFHosting.com. The place for dependable ColdFusion Hosting. http://www.cfhosting.com
