I have a Sony DCSF1 that is 640 X480 pixel but it says nothing about what the resolution is, What is the resolution and why some say pixels and some say resolution?? What should I look for to get the best picture to print??

-- Jess Russell (jar@hpnc.com), March 28, 1999

Answers

A PIXEL(picture element) is a single unit or packet of information that can represent any single combination of the entire range of colors and brightness levels that a camera or input device can capture(in theory at least... :-)) Basically it's one dot that can be any shade.

RESOLUTION is a way of expressing the number of something that's present in a given volume or measure. In the case of digital cameras, resolution is an expression of the number of pixels present in a given picture or image. Your camera's resolution can be said to be 640x480, or 307,200 pixels per image.

Some manufacturers are using either in-camera or software interpolation to raise the resolution of the final image. It's probably better to compare these units to other cameras based on the actual stated resolution of the CCD although some people have remarked that particular cameras seem to do a better job of interpolating an image than you could accomplish with a standard software package and an image captured by another camera. Agfa seems to be the leader in this field and Epson is doing it too.

It gets trickier with monitors and printers. On most systems the monitor's resolution is generally set to 72 PPI, or Pixels Per Inch. This can vary depending on the resolution your video card is set to display and the size of your monitor. With printers resolution is often stated in very tricky terms.

Some printer manufacturers(Epson, in particular) like to point out how many dots per inch their printers are capable of printing. They probably do this because most people look at numbers and automatically assume bigger is better and that Dots Per Inch is equivalent to Pixels Per Inch. The thing to remember is that printed DOTS are usually only capable of being ONE of a very limited number of colors, typically White, Black, Cyan, Magenta, or Yellow and are not comparable to PIXELS which can be nearly ANY color. It takes a matrix, or group, of several of these dots to represent the shade and brightness level of a single pixel. So the thing to remember here is that a higher DPI rating is preferable, but is not equivalent to PPI.

For instance, I have an Epson Stylus Color which is a 720 DPI printer, but it seems to print much better at a far lower 128 to 256 PPI. At 128 PPI this amounts to actually using a matrix of about 32 printed dots of ink to represent each pixel. Newer printers that can vary the size of the ink dots and can combine dots by overprinting in the same area will complicate this further so you really have to look into the type of printing technology to determine how many pixels a printer can print in an inch. Naturally, a greater number of pixels printed per inch is preferable in order to minimize the eye's ability to make distinctions between each separate dot. Some printing technologies like dye-sublimation printing can use a lesser number of dots per inch and still achieve excellent output by blending the colors printed to form each individual pixel. From what I've read in terms of feedback from other users who've posted to this forum, and what I've seen personally, the leading choices seem to be the HP Photosmart printer and the Epson line of inkjet printers. Alps makes a couple of units, but many people have complained of banding problems. I've seen output from both the Epsons and the HP printer and found both to be very impressive. Of the two types of printers the HP's output looks more photoprint-like and very well blended, but the Epson strikes me as being considerably more detailed. If someone would manufacture a unit that uses HP's printing method, but prints at anywhere near Epson's resolution for a reasonable price I'd be a very happy buyer. Maybe someday. I suspect it's a case of "You can have it Fast. You can have it Good. You can have it Cheap. Now pick any 2 of the three." Good Luck and Good Picking.

-- Gerald Payne (gmp@francorp.francomm.com), March 29, 1999.