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Old Oct 14, 2004, 1:53 AM   #1
rg7
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A small question about making 8x10 prints. I have a 5 megapixel camera. As far as I can tell, this isn't quite enough resolution to print an 8x10 at 300ppi. Which method would yield better results: interpolating the image to equal that necessary, or simply printing the picture at a slightly lower resolution (say, 290 ppi)??? Thanks in advance.
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Old Oct 14, 2004, 2:49 AM   #2
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I am no expert, but I seriously doubt you would be able to tell the difference in 290/300 ppi. 5MP should be more than enough for quality 8X10's. One way to find out is printing them out and seeing for yourself. Good Luck.:G
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Old Oct 14, 2004, 2:27 PM   #3
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I would encourage you to do the comparison yourself.

I have printed decent 8x10s from photos with 2MP (as a result of cropping a larger image). I did the test--I printed one "as-is", and a second one after up-rezing to 300ppi. I could tell absolutely no difference between the two prints.

Now whenever I want to print, I don't even worry about the ppi. After doing my post-processing, I crop to the desired print ratio and send it. No sweat.

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Old Oct 14, 2004, 3:15 PM   #4
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I would bet this is printer dependent. Your printer might not even print at 300 dpi, so sending it the picture at 300dpi might actually cause it to ignore and reduce the data before printing.

Other printers might prefer 300dpi and then it could be printer dependent. I do agree with GoCubs that I bet you won't notice the 10dpi difference.

Eric
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Old Oct 14, 2004, 4:16 PM   #5
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10 dpi difference? Most people couldn't tell the difference between a 5mp print and a 6mp print when printed on 8x10 (assuming the same quality camera and scene).
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Old Oct 14, 2004, 6:07 PM   #6
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rg7 wrote:
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A small question about making 8x10 prints. I have a 5 megapixel camera. As far as I can tell, this isn't quite enough resolution to print an 8x10 at 300ppi. Which method would yield better results: interpolating the image to equal that necessary, or simply printing the picture at a slightly lower resolution (say, 290 ppi)??? Thanks in advance.
A typical 5MP camera produces an image of around 2592 x 1944 pixels. After cropping for the correct aspect ratio (ratio of width to height) for an 8x10" print, this works out to around 243 pixels per inch (1944 pixels / 8 inches = 243).

Personally, I can't see the difference going to any higher resolution on my printers once you get up to around 200 pixels per inch.IMO, a 3MP model is plenty for this print size from most printers, at typical viewing distances.

Now, if I send a photo out to be printed, I will usually interpolate it to 300 to be safe (although this is probably not necessary on most printers). I'd try it both ways yourself.

You'll needan image size of3000 x 2400 pixels for an 8x10" print at 300 dpi.

I'd crop your photo for an 8x10" aspect ratio (this will work out to around 2430 x 1944 from most 5MP models). Then, print one. Then, interpolate the cropped image to 3000 x 2400 pixels and print another one. I doubt you'll be able to see any difference.

If you don't have a tool for interpolation, try Irfanview (free at http://www.irfanview.com ). Make sure to download the free plugins, too. You'll find the interpolation algorithms under Image, Resize/Resample. I usually use Lanczos (although I've talked to others that think that B-Spline is better).


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Old Oct 14, 2004, 8:15 PM   #7
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I have some very nice 13 X 19 inch photos taken with a 2.6 megapixel Canon Powershot Pro90. I have "rezzed up" some using Genuine Fractals and Photoshop elements. My best shots were printed on Epson heavyweight matte paper on an Epson 1270 or my new Canon i9100.

More megapixels is a better solution, everything else being equal... but everything else rarely is equal. Good framing and post processing can do some great things with GOOD files. It's a mistake to consider only megapixels.


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Old Oct 14, 2004, 9:19 PM   #8
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Whoa! Let us step back a minute. The only meaningful number is the total size of the image. For example, assuming I have a 3000 x 2000 image and the preferences of Photoshop are set at 72 dpi, my image will be a 72 dpi image and the "size," of the print is then dependant on the printer dpi output.

So with an 8 x 10 you will want the higher dpi for the final print, but the quality of the print is determind by the ACTUAL size of the image. Interpolating up is a reasonable solution for this problem. At some point you reach a limit, but this is determined more by the detail of the image rather then the problems of interpolation.

So, I normally print 16 x 20's from my 5 Meg camera, interpolating them up to 100 Megs, or roughly 8000 dpi.

An 8 x 10 would need little or no interpolation to get a good result.

Dave
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