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Old Nov 4, 2002, 2:47 PM   #11
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jmcdev1....If the machine operatives are doing auto brightness/contrast and cropping, I'm tempted to do as little as possible to avoid JPEG file losses. Perhaps do lossless cropping/rotation and only re-touch when absolutely necessary.

Depending on your web connection and quantity of prints, you may have no choice but to downsample to get files across.

Try sending the same image file, under/over exposed and different crop sizes. When the prints come back, scan at highest res. and compare with your original file using high zoom. Don't expect colours to be a perfect match though, as their printers work in dyes not as rgb monitors.

If you find prints are not being corrected, then correct in your editor and stick to a service that can give consistent results.
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Old Nov 4, 2002, 3:51 PM   #12
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Default Resolution and printing

Thanks for the advice, Lyn and Voxmagna (?great voice, big sound, loudmouth? . Lyn, I'm going to contact them and see what resolution they require (Snapfish). Voxmagna, I did send uncropped files and they cut my daughters head off (they cropped equally all around the edges). So I'm going to try cropping before sending. The colors came out an exact match to what I see on my Toshiba laptop monitor, so that was a pleasant surprise. I was dreading having to play with Adobe Gamma to try to match their colors. Thanks for the advice, folks. I'll get with them and find out what they need me to send them.
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Old Nov 4, 2002, 5:55 PM   #13
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jmcdevil1... watch out colour matching or photo-editing on laptop lcd displays! So it looks then as if a little experimenting has to be done to find out what they do? Strange they are cropping equally, since most cams do about 1.3:1 and you need 1.5:1 for 6"x4" prints. I worked out that's just a bit off either side in landscape, although some might leave a white border on the print. Glad to help.
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Old Nov 6, 2002, 3:15 PM   #14
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Hello,

Thanks very much to all who have answered my first question - I think I have a much better idea of what a camera's "resolution" means now. I'm going to get some files from the various cameras which I am looking at (conveniently on this site) and print them to find a camera which does what I need.

The other question I posed dealt with printers. Could someone please explain to me why one needs a printer with more than 300-400 dpi? It seems that this is the upper end of what is needed in capturing an image, yet all the printers brag about being 1200, 2400 and even more dpi.

What does this extra dpi do to make a print look better when a 400 dpi image (captured) will supposedly look great?

thanks,

Steve
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Old Nov 9, 2002, 3:01 PM   #15
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smf.. I'm sorry I missed the last part of your post. Printer resolution comes into its own when you make bigger and bigger prints. So 300dpi (dots per inch) is very good for say a 6X4 print. You won't be able to see any white between the dots! Resolution is best tested for on diagonal lines. BUT as you magnify your printout to larger sizes, outline edges will show more 'jaggies'. - similar to what you see zooming in a photo-editor. So you need more ink dots to keep the edges smooth.

Resolution isn't everything, but sticking to your question, many printers (like some cams!), in software take a native resolution of say 600dpi and ''fill in' the spaces between by averaging the brightness and colour of the dots either side and or up and down. This is called interpolation, although some makers call it 'resolution enhancement'. They also use a technique called 'micro-weave' or dot wobble. This is a really fudge to give an illusion of sharp, continuous edges

The normal rule is, you can't put something back if you hadn't got it to start with so it's clever, but not the same as having dots based on real info. I don't want to confuse you but virtually all printers have to do some of this anyway, because most cam files don't 'map' exactly to the printer anyway, your SVGA graphics card output to monitor is the same.

So why print 1200dpi? Take a 6X4 printout. Perfect image translation would need roughly 34Mpix from your cam! Most printers are really 300 or 600 dpi native and 'dot doubling or trebling' by software averaging. OK this is all very well in theory, but if you're using OEM ink refills and paper, its unlikely your printer in practice will lay this high res. down to paper, and its more likely to overprint dots which were correctly placed in the right place!

So, at the moment, I think the most consistent prints should be coming from laser scanning on to photo print paper. Most shops are using 300/400dpi printers. However, the print paper resolution is only limited by its photo emulsion grain (very high) and only the laser light optics and colour registration should limit effective resolution.

Contrast and tonal range is regarded as the first impressive quality feature in a print, before marginal improvements in resolution. So a printer which can accurately lay down a large volume of ink per hit on the right paper, without bleeding into the next dot, just might give a more pleasing print, than lesser ink but more dot detail. Please don't ask me which printers are the best, as running costs are generally a big factor!
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Old Nov 13, 2002, 11:42 AM   #16
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Default Printing resolution

Hello,

Thanks for the answer - I'm a little slow though and was wondering if you could look at a more concrete example and see where I'm not getting this.

Say I didn't read Steve's reviews and went out and bought a camera which had 4 pixels, 2x2.

Now, I take a photo and print it at 10"x10". That will make each pixel 5"x5".

If my printer is 300 dpi, it will print 3000 dots x 3000 dots (10"x10").

I have been told that 300dpi gives a very good quality, so what this picture will look like is 4 big pixels, although they will be smooth and I shouldn't be able to see the printer dots that were used to print the pixels.

I don't understand how a 1200dpi printer would look any better on this photo.

I guess where a higher resolution printer might look better is if one used a high enough resolution camera so there were actually more pixels to print - but then again if 300dpi looks pretty good and can the human eye actually tell the difference?

Thanks for your replies - I have to admit this has become a bit esoteric and my original questions from the thread have been answered, but I'm curious nonetheless.

Steve
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