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Old Oct 1, 2003, 7:01 AM   #1
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Default How many Mp's needed to blow up pics to A0 or A1 size pics

hey there evrybody.

i do a lot of large printing of pictures that take and i was wondering if a 5mp or 6mp will be enuff to blow up pics clearing and sharply tyo a A0 or A1 size print. or will i need to go higher.

any advice is always welcome.
thanks.
Bryce.
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Old Oct 1, 2003, 7:54 AM   #2
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Default Mmmmmmmm.........

You need 6MP or higher........thats the best....
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Old Oct 1, 2003, 8:49 AM   #3
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Default Re: How many Mp's needed to blow up pics to A0 or A1 size pi

Quote:
Originally Posted by snakeman
hey there evrybody.

i do a lot of large printing of pictures that take and i was wondering if a 5mp or 6mp will be enuff to blow up pics clearing and sharply tyo a A0 or A1 size print. or will i need to go higher.

any advice is always welcome.
thanks.
Bryce.
As far as print sizes, many will argue that 150 pixels per inch is plenty of resolution, with anything more a waste, since the human eye won't be able to tell the difference at normal viewing distances.

Others will argue that 200, or even 300 pixels per inch is necessary for the best quality.

Here's a chart that may help. You'll probably find that the "good" column is all you need (unless you're going to examine the print under magnification).

http://www.cordcamera.com/products/d...ct_ratios.html

IMO, anything 150 or greater is fine for prints up to 8x10", and even less is fine for larger prints (because you'll be viewing them from further away).

Here's another chart that takes popular digital camera image sizes, and shows how many pixels per inch you'll be sending to the printer driver for popular print sizes:

http://home.earthlink.net/~terryleed...tables.htm#ppi
Also, you can interpolate an image using software. This does not increase the detail captured originally, but it does add pixels (based on the value of adjacent pixels). This lets you print larger images without pixelaton.

A good free package is irfanview. It has a very sophisticated Lanczos Filter based interpolation algorithm (you'll find this option under the resize/resample menu option). You can download the software (free) from this link:

http://www.irfanview.com

Here is an article discussing interpolation:

http://www.megapixel.net/html/articl...rpolation.html

I'd suggest going to at least 150ppi for your prints.

Interpolation will not add detail, but it will allow much larger print sizes without pixelation.
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Old Oct 1, 2003, 10:11 AM   #4
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I'm guessing you need a 4 or a 5mp, and maybe a 6mp if you intend to crop quite a bit.
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Old Oct 1, 2003, 10:16 AM   #5
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It depends primarily on the geography in the frame. Let me give a quick tutorial:

Unlike film which is "grain limited" for enlargement purposes, digital is nearly always "resolution limited". To make prints at "any" size other than the one optimal size for the print density needed a process called "interpolation" is used to either add or remove pixels.

Let's use an example. Say the capture was 800x600 native resolution. Further, let's say you needed 300 dpi print resolution. So dividing 800 by 300 dpi we get 2.6" and dividing 600 by 300 we get 2". The "native" print capability is 2.6" by 2" for a 300 dpi print.

To print at any other size the file must have pixels added or deleted. Deleting pixels has little effect on the absolute quality of a printed image, but adding pixels requires that "sufficient" pixels were alloted in the first place to properly define the boundaries of fine detail in the capture. The smaller the field of view (think head and shoulders portrait as opposed to wide angle infinity landscape) the fewer pixels it takes to do this so that the interpolation software can do its job and render a good likeness of the subject material in the enlargement.

Excellent 80x100 inch prints have been made from 3 megapixel Canon D30 captures of subjects occupying a relatively small field of view in the frame. On the other hand for a 16x20" print of a detailed landscape at hyperfocal infinity, even the 11 megapixel Canon EOS-1DS or 13.8 megapixel Kodak 14n are pushed to their limits. This type photo for gigantic prints is best left to large format film or high resolution digital scanning backs for medium format cameras.

This is simply a rather long way of saying that how many pixels you need for a given print size depends greatly on the subject, degree of detail, distance from lens to subject and especially the amount of geography which is captured within the field of view. Unfortunately no simple answer is available, but for "general" 35mm color film or transparency replacement around six megapixels of professional level sensor capture is preferred.

Lin
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Old Oct 1, 2003, 10:35 AM   #6
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Default Convesion of A1 to Inches?

Lin: Very informative piece, thanks for writing that.

Does anyone know of a conversion chart for A0, A1, etc, sizes to
inches?
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Old Oct 1, 2003, 10:47 AM   #7
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A0 and A1 are very large (poster size). That's why I suggested interpolation would be needed to prevent pixelation in my previous post in this thread.


A0
84.09 x 118.92 cm
33.11 x 46.82 inches

A1
59.46 x 84.09 cm
23.41 x 33.11 inches

A2
42.04 x 59.46 cm
16.55 x 23.41 inches
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Old Oct 1, 2003, 10:54 AM   #8
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I have printed some beautiful pictures at 13 X 19 from files taken with my 2.6 MP Canon Pro90. I use Genuine Fractals to 'rez' up the files. I print with an old Epson 1270 on Epson Heavyweight Matte paper. Once properly matted and framed, the pictures look great.

I found a chart on the Web that lays out the dimensions of papers in inches and CMs. Have lost the link, but you can find it easily using a search engine with key words like "paper dimensions". The one I saw was produced by one of the paper companies.
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Old Oct 1, 2003, 10:58 AM   #9
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Genuine Fractals has been around for a very long time, and works well

There are many other types of interpolation as well. I've found that the Lanczos Filter based algorithms seem to do a little better (but this is a matter of great debate).

Qimage Pro uses a Lanczos based interpolation algorithm, and most of their users think it's the best.

As I mentioned before, the free irfanview package also includes this interpolation technique. It's free:

http://www.irfanview.com
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Old Oct 1, 2003, 11:03 AM   #10
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To both Jim C & Wildman That's great information, thanks!
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