Q1: What is the relationship between dpi and pixels?
- The relationship between DPI (dots per inch) and pixels is dependent upon the resolution
of your output device. For the Web, your output device is the screen, and the standard DPI
is 72. That means that if there are 72 dots in an inch on a monitor, each pixel on the
monitor's screen is 1/72 of an inch in size. On laser printers, the DPI is 300 to 1200,
and the pixel size is therefore 1/300 to 1/1200 of an inch.
Q2: Is scanning at 100dpi sufficient for Web work?
- When scanning (or reducing high-resolution images) for the Web, use 72 dots per inch
only. Anything more than that will be overkill and would not be seen on anyone's screen.
Q3:What technology can I use for converting high-resolution images or documents
to the Web?
- Try Acrobat from Adobe (http://www.adobe.com) or
Net-It Now (http://www.net-it.com) to convert entire
documents. With Acrobat the user has to load a plug-in which can be frustrating for your
users. Net-It Now loads a "Net-It Printer" into the Webmaster's application
printer choices, and eliminates the need for plug-ins. By choosing the Net-It Printer, the
document will be converted entirely into java scripts.
- HP, www.image.hp.com, Microsoft and Kodak are
recommending the FlashPix standard for high quality images. HP's site has a good
explanation of how the FlashPix standard works.
Q4:How can I balance the need for high-quality printable images with the need
for quick downloadable images?
- Keep in mind that screen resolution is only 72dpi. The technology is different when
viewing a graphic on-screen as opposed to printing it out on paper. Instead of going for
an all-in-one-resolution, you may want to opt to have separate downloadable files in
high-res for those who want to print them out on paper, and keep your on-screen files
low-res and quick loading.
[Eldon Sarte, firstname.lastname@example.org]
Q5: How should I create high-resolution images if the users screens are at
the standard 72 dpi?
- Create your hi-res images using the richest palette on your system (24 bit - 32 bit)
using Photoshop, Canvas, DeBabelizer or PaintShop Pro. Save as appropriate, then reduce
both the resolution (DPI) to 72 and the color palette to the 216 Web-safe colors and
re-save as a separate GIF, JPEG or PNG file as your Web display graphic.
Q6:Which color palette should I use for Web work?
- You can either choose PANTONE's ColorWeb, which becomes your system palette when you
select it, so you can't select a color that's not Web safe, or there are various free-ware
plug-ins that you can find on Adobe's site http://www.adobe.com.
Lynda Weinman, author of has a Photoshop swatch you can load.
Q7: If I use a 1.4 million pixel digital camera for high resolution, then apply
an image of this resolution to a Web site, how does scanning the image (at 100dpi) affect
the computer screen quality?
- Integrating hi-res images usually involves a separate thumbnail or link to the hi-res
file for DOWNLOADING, not viewing on the screen. You'll most likely be anti-aliasing your
low-res display images, and that's why (among other reasons) they look grossly rendered
when printed on a higher resolution output device. On the other hand, a high-res image
downloaded and opened in a drawing or paint environment and then printed will look