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Old Apr 30, 2003, 2:20 PM   #1
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Default Is resampling useless

A digital image containing a resolution of 2560 x 1920pix at 72 dpi can contain a size of 35 x 26" aprox, is not to be print (offset) at the same size, then what is a role of resampling. By resampling an digital image 72 to 300 dpi a desired result can not be obtained than to me resampling is useless.
I m not sure but I think (may be wrong) if an image editing software like ps or corel adopts an digital image at the res of 72dpi as default, can be able to print offset at the same size of an image and not best but good quality. If 300 dpi is every thing than why the default value of these editing programs are not been settled at 300dpi.
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Old Apr 30, 2003, 3:04 PM   #2
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Forget dpi and image size to start. If cam records 2560X1920 pix that's what you have. Your choice is to have those pixels either close together for a smaller image, or further apart to make a bigger image.

So if you told your editor to print an image which was 72dpi (pix/inch) you would have the pixels/dots spread out to make a 35"x 27" image. If you told the editor to print the same pic using 300dpi (pix) per inch, you would have an image 8.5"X 6.4". You haven't made any new pixels, or thrown away any, just scaled or zoomed the image by increasing or decreasing the space between original pixels. THIS IS NOT RESAMPLING but SCALING. - changing the distance between the pixels or dots you already have!

Resampling is when you start with say 2560 X1920 and create an image which is say 256 X 192 pixels by only using 1 pixel in 10 (all the others are thrown away). You do this to make pics and files smaller for email. If you tell an editor to print a file at a particular size in inches, it will put the most pixels per inch it can from what you have, into that size (more for small prints) less for big ones's.

PC monitors unlike printers can only show about 72 dpi - and you have hundreds more dots of information. In this case, an editor will downsample the preview, but not the real file, so that what you see for a picture filling your pc screen, is actually an image more like 800 X 600 (approx 72dpi). This is real downsampling, but is only to get a normal size pic on the screen. IT DOES NOT CHANGE THE ORIGINAL IMAGE FILE. Exactly the same thing happens with small 'thumbnail' images.
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Old Apr 30, 2003, 4:14 PM   #3
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Great way to explain the concept!
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Old Apr 30, 2003, 4:44 PM   #4
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Default Re: Is resampling useless

Thanks for explaining in detail!
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Old Jun 21, 2003, 10:00 AM   #5
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I love this explanation! Thanks! I have a related question as I am learning web design. I have Macromedia Flash software and am planning to purchase both a digital camera and a digital camcorder for posting both stills and movies on my websites. What is the minimum specification (resolution) I will need for this kind of work? I am not concerned about high resolution prints - this is all for web work.

Any camera or camcorder recommendations from web masters would also be greatly appreciated!
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