How many pixels does a digital image need for a specific print size.?

Question

I'm trying to make a 20X30 inch image, but am not sure how many pixels the digital image should be to begin with so it doesn't look pixilated.

Answer 1

Whatever camera you use, you can interpolate the image with software to avoid pixelation. When you interpolate, the computer 'makes up' information between the actual pixels. In effect, you avoid a choppy, pixelated print in exchange for a smooth, albeit soft image. Most software image editors can do this. With PhotoShop, you´d use ´bicubic smothering´. There´s also a program called Genuine Fractals that specializes in this (not free).
So, with that out of the way, how many megapixels is ACCEPTABLE for a 20x30 print depends of the viewing distance. For perfect quality, you´d want 54MP (see footnote). Not even a top of the line digital SLR has that kind of resolution. But 12MP will let you see tons of detail when you view the picture from about 1 foot. 3MP will suffice if you view the picture from about 6 feet away.
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For fantastic print quality, the standard is 300 dots (or pixels) per inch.
That works out to 300dpi*300dpi (for every square inch)*20inches*30inches = 54 megapixels.

Answer 2

I regularly provide 11x14 prints from my D70 (6.0MP) using pro glass (f/2.8 or better) which is not the same quality image as that from a point and shoot camera. FWIW, I only shoot in RAW then post process using Photoshop keeping the image in photoshops native PSD format. Only when I'm ready to print it do I convert it to a jpg. I also use both monitor and printer profiles to ensure color calibration is optimized. Even then I frequently have to adjust a bit to get the best possible print. My understanding is you should be able to print poster sized prints (24x36) that look good but like you mentioned viewing distance will come into play for prints this large. Note: I should add that these prints will not be at 300 dpi. Why you must have it at 300 dpi I don't know but if you really require that regardless of optical quality, then certainly an 8x10 will be about the largest you can print. HTH.

Answer 3

My "rule of thumb" is that most people can't see pixilation without a magnifying glass at 100 or more pixels per inch. So you would need at least a (20 inches * 100 * 30 inches * 100) pixel camera, or a 6 megapixel camera. More megapixels would be better if you got really good eyesight, or you're going to have to please a fussy customer.

The standard for book publishing seems to be about 300 pixels per inch. Newspaper photos are typically somewhat less than 100 pixels per inch.

Answer 4

For a picture that size I believe you Will need at least a 5 Mega Pixel camera but higher would be better.

Answer 5

To obtain a good printed image, so much in printer paper as in photographic paper, it will be necessary to have an image in file with a minimum resolution of 300 ppi

Answer 6

You should use as maximum as you can, because this will give you more good look, about print size, software like(corel draw, Adobe photoshop) have option to print size adjustment.