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Old Jan 12, 2005, 10:19 PM   #1
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i have some photos of a white water rafting trip that were taken at 3008 x 2000 resolution. any ideas on how big of a print i can buy online w/o losing much quality? do u think they would be ok at 16 x 20? additionally, im only aware of ophoto that will do prints that large...any other suggestions would be greatly appreciated.



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Old Jan 12, 2005, 10:49 PM   #2
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I'd suggest that you use a program to interpolate your picture if you plan to print 16x20, the picture would look good, but not from too close... If you want to have an idea of what this would be like, make a printof a crop that measures 500x750, print it in 4x6 size(this is a bit below what you'd get but still similar).
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Old Jan 13, 2005, 10:32 AM   #3
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tommyesq73 wrote:
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i have some photos of a white water rafting trip that were taken at 3008 x 2000 resolution. any ideas on how big of a print i can buy online w/o losing much quality? do u think they would be ok at 16 x 20? additionally, im only aware of ophoto that will do prints that large...any other suggestions would be greatly appreciated.



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Roughly speaking, one pixel=one printed dot (although I think this can change in special circumstances--someone correct me if I'm wrong)...

For really good quality, I think you need around 300 dpi. So this would give you around 10"x6" (3000/300 x 2000/300). But most people don't print at 300dpi (they usually use 200-something).

If you print yours at 16"x20", that would give you a minimum dpi of around 125dpi. I think 125 dpi is kind of low. I would try to aim for something around 200. So I think you need to interpolate or something...
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Old Jan 13, 2005, 1:12 PM   #4
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That size would be pushing it for direct printing.
But if they are sharp enough you can enlarge the picture (with interpolation of new data) and it might come out well. But it depends a lot on the subject and how well the picture was taken.

I have pictures that are 3072 x 2048 and are interpolated a bit and printed 11x14 and all but one came out really well (I have high standards.) At least one of them could probably have been printed larger.

It really matters on the picture. I think that places like walmart will print that big, but I'm not sure.

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Old Jan 13, 2005, 2:38 PM   #5
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It depends upon what you're expecting, as others have said. I printed a 3.2 megapixel (2048 x 1536) print at 16x20 (I know, GASP!) And yes, if you get close, you can easily see the pixels blown up. But, from, oh, 5 feet or farther away, it looks fine. (I was going to write "perfectly fine" but for many people here, it would probably would not be "perfectly" anything. Let's just say that I'm not ashamed to have it nicely framed and hung on my wall).

I got my 16x20 poster print from Snapfish (www.snapfish.com). Many people think that they have only so-so quality printing, but I find it to be acceptable. (They really pissed me off this Christmas by not processing my prints in the time they promised and then refusing to ship overnight, but that's not a big deal this time of year.) They recommend that the minimum file size for 16x20 is 1920x1536 pixels. That's pretty low. And the snapfish 16x20 is only $15.00 ... so order it... if you don't like it, you're not out that much.


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Old Jan 13, 2005, 3:06 PM   #6
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Someone on this board in another discussion said he had a 2Mp image from his UZI printed at 16 X 20 and hung it in his office. He said people were surprised when he told them it wasn't a photograph. I'm guessing he had it behind his desk or someplace where people did not view it close-up.

Your 6Mp image gives a 125 PPI 16 X 20. You can downsample the image to 125 PPI and print it 4 X 6 or 8 X 10 to see what the results might be like. You could also upsample the 125PPI image back to 300 PPI to see what that would look like. I generally upsample anything under about 150 PPI. 125PPI upsampled to 300 isn't the best quality, but you might find it is sufficient for viewing at the distance you would see a 16 X 20 from. Different subjects require varying PPI and viewing distance is a factor. You might be happy with your 16 X 20 print. Let us know how it works out if you do it.

Quote:
Roughly speaking, one pixel=one printed dot (although I think this can change in special circumstances--someone correct me if I'm wrong)...
The old 8 and 10 picolitre printers put down 16 dots to make a pixel. 4 & 5 picolitre printers use 32 dots. I've read that 2 picolitre printers use 64 dots and I'm guessing 1 picolitre printers must use 128 dots. As the dots get smaller you have to use more of them. Printers are rated in DPI based on these maximum number of dots. They don't actually use all of the dots for every pixel as light has to come from the paper to provide subtractive colors. You would use the full DPI only when mixing colors to make black (I think).

The old LPI printing formula was to provide pixels at 1.5 times the LPI for printing and 2 times the LPI for best possible quality. Why you need more pixels than lines has something to do with the diagonal distance between the pixels.

Do the math on an Epson 2200 with 4 picolitre dots. Its maximum resolution is 2880 X 1440. Divide the 2880 DPI by 32 dots to make a pixel and you get 90 LPI (The larger number is usually the vertical and represents line resolution). 2X would give 180 PPI input for best quality using the formula. Under magnification you can see slight improvement over 180 PPI, so the formula isn't absolute. But the resolution photo inkjets can take is generally overstated. I don't think that resolution has changed much over the past few years. The DPI of photo printers has generally gone up in inverse proportion to the dot size with the input PPI about the same.


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Old Jan 13, 2005, 3:14 PM   #7
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Slipe is right, experiment and see if the results work for you. I would suggest one different kind of experiment, crop out a 4x6" section at 125ppi and print that. Pick the area with the most detail.
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Old Jan 13, 2005, 3:26 PM   #8
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Don't know how well this stuff works, but here is a read on Moose Peterson's site

http://www.moosegallery.com/articles/nik.html on how he makes mammoth prints from tiny coolpix type cameras.
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