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12/17/2002 05:37:20 PM · #1 |
| I'm kinda confused when it comes to resolution. If you take a picture at a high setting and then resize it to 640x480 for this challange, doesn't that degrade the quality? I don't understand how this works and thought this would be a good place to find an answer.........thanks. |
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12/17/2002 05:42:53 PM · #2 |
One of the many film technical mavens here will no doubt jump to your assistance. But I wanted to make a pitch for the very useful "Digital Photography for Dummies" (with which I am not in any way affiliated.) In particular, she does a fine job of covering all three rather complex meanings of "resolution."
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12/17/2002 05:47:24 PM · #3 |
Originally posted by jwagley:
I'm kinda confused when it comes to resolution. If you take a picture at a high setting and then resize it to 640x480 for this challange, doesn't that degrade the quality? I don't understand how this works and thought this would be a good place to find an answer.........thanks. |
Yes it does, but the amount of degradation is minimal (usually) when sampling down (to a smaller size) than when trying to enlarge. Usually judicious application of the Unsharp Mask Filter (or equivalent) will substantially restore any lost detail in the reduced image.
Besides re-sizing, some people crop a smaller number of pixels out of a larger image, so the resampling may not be so extreme as you might think.
But I always shoot at the highest resolution I have in case I ever want to print it. If I know for sure the images will never be printed I sometimes shoot at lo-res when I need a ton of images to fit on the card.
Also, check out the new tutorial on Creating Printable Images by John Setzler, as it discusses the resolution issue from the other direction.
Message edited by author 2002-12-17 18:15:34. |
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12/17/2002 06:07:47 PM · #4 |
Originally posted by Jak:
One of the many film technical mavens here will no doubt jump to your assistance. But I wanted to make a pitch for the very useful "Digital Photography for Dummies" (with which I am not in any way affiliated.) In particular, she does a fine job of covering all three rather complex meanings of "resolution." |
I know of four factors related to "resolution." Unfortunately, almost everyone uses the term DPI for all of these.
Pixels per Inch/cm -- Discrete units of data in the file/unit length
Dots per Inch/cm (monitor) -- 1) number of physical phosphor spots/LCD addressable nodes(?)/unit length; same as dot pitch 2) size of discrete spots hit by the electron gun; same as display resolution
Lines per Inch (printer) -- number of halftone spots/unit length used to simulate continuous-tone on a monochrome device (laser, inkjet, printing press). These spots are typically built up out of 1-200 laser spots (see below) and may be in a regular pattern or randomized (stochastic screening).
Spots per Inch/cm (printer) -- diameter of laser where it hits the imagable media.
Message edited by author 2002-12-17 18:08:23. |
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12/17/2002 06:42:58 PM · #5 |
ever since my second challenge I have been shooting the pics for the challenge in 640x480 so there is no problem in file size or image size, or a quality issue with resizing.
gee I wonder if this why i get some comments about my poor croping capabilities :) lol
James
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